Rice (incl. transport guidelines)

Infobox on Rice (incl. transport guidelines)
Example of Rice (incl. transport guidelines)
Facts
Origin	This table shows only a selection of the most important countries of origin and should not be thought of as exhaustive. Europe: France, Italy, Hungary Africa: Egypt Asia: Burma, China, Pakistan, Thailand, India; East and South-East Asia being the main areas of cultivation. America: Argentina, Uruguay Australia
Stowage factor (in m3/t)	1.359 m3/t (bulk cargo) 1.5 - 1.6 m3/t (jute fabric bags, 100 kg) 1.81 - 1.95 m3/t (paddy rice, bags or bulk) 1.34 - 1.39 m3/t (cargo rice, bags or bulk) 1.39 - 1.45 m3/t (white rice, bags or bulk) 1.48 - 1.56 m3/t (broken rice, bags or bulk) 1.84 - 2.12 m3/t (rice, unhulled) 1.44 - 1.56 m3/t (rice, hulled) 1.39 - 1.56 m3/t (rice, polished)
Angle of repose	-
Humidity / moisture	Relative humidity: 70% Water content: 13 - 15% Maximum equilibrium moisture content: 70%
Oil content	-
Ventilation	Loading as bulk cargo: surface ventilation. Loading as general cargo: air exchange rate 15 - 25 changes/hour. Good surface ventilation and airing are necessary.
Risk factors	At an excessively high water content in particular, rice has a tendency towards self-heating. Water contents of > 15% and relative humidities of > 75% result in self-heating of the cargo due to hydrolytic/enzymatic fat cleavage. Rice is highly odor-sensitive, prone to contamination and shrinkage. Beware of infestation.

Rice (incl. transport guidelines)

Transport guidance on bagged rice

As a cereal grain, rice is the most important staple food for a large part of the world's human population, especially in Asia and the West Indies. It is the grain with the second-highest worldwide production, after maize (corn).

Since a large portion of maize crops are grown for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed worldwide by the human species.

Therefore we have extended the article on rice to a transport guidance, in order to prevent loss as much as possible.

Introduction

1.1 Types of rice cargoes

Rice, or Oryza, can vary in height from 1 – 6 m. It is an extremely adaptable plant; it has an efficient system of air passages connecting the roots and the shoot. This enables it to grow in dry upland soils, in irrigated fields, or along flooded river beds, Rice is largely self-pollinated, but cross-pollination does occur in degrees ranging between 1 – 30%.

There are over 85.000 varieties of rice in the research stocks of the International Rice Research Institute (IRRI), and there are over 120.000 cultivars known to exist. The familiar distinctions to Westerners of long grain versus short grain, or white versus brown, are but two. Like wheat, oats or maize, rice is a cereal. It is a basic diet for over 50% of the world’s population and is therefore the most important crop in the world. The range of varieties is so great that no internationally recognised system of classification exists, although repeated efforts have been made since the Rice Congress at Valencia in 1914 urged ‘the formation of a real botanical classification of the varieties of cultivated rice’. Two species are cultivated, Oryza sativa and Oryza glaberrima (wild rice – in West Africa).

Asian rice, Oryza sativa, is divided into two categories, both of which include glutinous and non-glutinous varieties. Indica rices’ grains are longer and more slender, and they usually remain separate when cooked. Japonicas have shorter, rounder and more translucent grains which quickly become slightly sticky. Indica grains are divided into medium (5 – 6 mm) or long grain (more than 6 mm). It was proposed in 1958 to coin another name, javanica, for the bulu and gundil varieties of Indonesia. Most rices grown in the tropical zones belong to the indica and javanica groups, which tend to have a fixed growth period. Japonia rices have shorter grains (4 – 5 mm) and are also different in terms of taste and smell. They are highly sensitive to photoperiod, or day length, and so do poorly in the short-day tropics. They are, however, widely grown in N. China, Korea and Japan. Then there is glutinous rice, (Oryza sativa L. glutinosa) which is specified as having a starch level of 99$ amylopectine. The grains are completely opaque, and this rice tends to be reserved by Asian populations for confectionery and cakes.

The long grain varieties, Oryza indica, tend to be preferred by the people of Inda and SE Asia; the Japanese and Indonesians prefer the stickier, short grained variety Oryza japonica. Rice plants are usually grown in flooded fields known as paddies, although there are varieties which can be grown ‘dry’, for example in Tanzania, Zambia and the Philippines – these tend to produce a lower yield, however. The roots of the rice plants are kept underwater. The head of the plant, known as the panicle, contains small spikelets which produce grains of raw rice, known as paddy.

Before the paddy field is flooded, the soil needs to be broken up and levelled. In most rice-growing countries, the seeds are first sown in nurseries. Small corners of the paddies are set aside for sowing. On the first night, the seeds are often kept in water, to allow germination, then planted. About 30 days later, the rice plants are pressed into the mud in rows. The rice plants are often under attack from weeds or pests such as rats, worms, birds and snails – hence there are often fish in the paddy fields. Fish are no protection, however, against the other threats of hurricane, drought or rats.

Rice matures very quickly in the right growing conditions. The life cycle of the rice plant is generally 100 – 210 days; the average falls between 110 – 115 days. In temperate climates the average duration from sowing to harvest is about 130 – 150 days. Cultivars with growth duration of 150 – 210 days are usually photoperiod sensitive and are planted in the deepwater areas. Temperature and day length are the two environmental factors affecting the development of the rice plant, which can be divided into three phases:

• Vegetative – from seed germination to panicle initiation;
• Reproductive – from panicle initiation to anthesis;
• Ripening – from anthesis to full maturity.
  
  

Controlled irrigation dramatically improves yields – most rice needs between 250 – 600 grams of water for each grain of rice eventually formed. When ready for harvesting, rice is a golden yellow. Combine harvesters can cut the rice, separate the grain from the straw, and leave the straw in the field.

When harvested, rice typically contains from 15 – 22% (US) or 19 – 25% (Asian) moisture and therefore must be dried to a moisture content of 12 – 14% to prevent spoilage. The rice dries in the sun, or it can be dried by blowing hot air through piled sacks of grain, which reduces the risk of disaster from sudden torrential rain. Paddy is then stored to protect it from damp, heat, rodents, insects, birds and fungi; it can be stored in large pots or bamboo baskets, or in lofts or barns on stilts. Rice can be stored for years. Modern steel or concrete silos automatically control the humidity and temperature of the vast amounts of paddy which they contain.

After being dried and stored, the rice goes through the milling process, which removes the tough outer husk and inner layers of bran from the edible rice grain. Unfortunately, milling also removes much of the goodness, hence the gradually increasing demand for brown rice. However, most consumers like white rice, so the grain is also polished white, and sometimes also glazed with glucose and talc. From 100 kg of paddy (rough rice), 20 kg of husk and 80 kg of brown, de-husked rice can be obtained. From the milling process, 68 kg of milled rice (or parboiled rice, where the rough rice is exposed to steam pressure and the grain becomes harder and less sticky) and 12 kg of bran and other by-products are obtained. From the 68 kg, 55 kg can be expected to be wholegrain and 13 kg broken grain.

Rice is traded either as paddy or milled rice and an indication is needed in the description of the product i.e. paddy/brown/milled/parboiled. Other mentions needed are grain type (long or short), origin and the percentage of broken rice, for instance, Thai white rice long grain 5% broken.

Electronic sorting machines can classify the size, type and colour of each batch of rice and separate the different grades for packaging. The main patterns of good quality are:

• Colour – as white as possible (no discolouration, no imperfections);
• Whole grains – minimum percentage or broken grain.
  
  

Standards in most countries define the percentage of brokens and other imperfections allowed in each grade of rice, and the basis on which such percentages are measured.

1.2 Composition and nutritional value

The composition and nutritional value of rice varies with the nature of the soil, climate, variety, the conditions of culture – in particular the fertilizers used, etc; this it has in common with all vegetables and grains. But for rice in particular, the nutritional value depends on the degree of milling that is undertaken. Brown rice contains 8% protein, 70% starch and small quantities of lipids, fibre and minerals. After milling, however, the decline in beneficial elements is dramatic, see Table 1.1. This shows a dismal picture indeed when one considers the social, economic and, above all, taste pressure which encourages the milling of rice. The reasons for the dramatic fall in nutritional value after milling are as follows: The starch is found principally in the endosperm; the lipids, fibres, vitamins and minerals are concentrated in the cellulose layer. Glucose molecules are found in two forms; amylase and amylopectine, the proportion varying between varieties. Most current varieties contain 12 – 35% amylase, the rest being amylopectine. Glutinous rice is low in amylase and tends to stick together in cooking. Simple sugars such as sucrose are present in brown rice in the 0,6 – 1,4% range, and in white rice from 0,3 – 0,5%. Fibre is present in the shell of brown rice but hardly at all anywhere else and therefore only marginally in white rice. Proteins, the second major constituent of rice, are present in the endosperm in the form of 1 - 3µm granules but these are eliminated in the milling process. Of 17.600 varieties of rice analysed by the IRRI, the percentage of protein varied from 4,3 to 18,2% with a middle point of 9,5%. Table 1.2 shows the amino acid content of the different forms and elements of IR-8.

Table 1.1 - Effect of refining and parboiling on rice, 100 g.

	Brown rice	White rice	Parboiled rice
Energy, Kcal	360	365	370
Protein, g	7,5	6,7	7,4
Lipids, g	1,9	0,4	0,3
Fibre, g	0,9	0,3	0,2
Cendres, g	1,2	0,5	0,7
Thiamine, mg	0,34	0,07	0,25
Riboflavin, mg	0,05	0,02	0,03
Niacine, mg	4,7	1,6	3,5

Table 1.2 - Amino acid content of the different forms and elements of IR-8 - g/16,8 gN

	Brown rice	White rice	Pericarp	Aleuron	Embryo
Amino acid
Isoleucine	4,5	4,7	4,5	4,3	3,8
Leucine	8,3	8,5	8,2	7,8	6,8
Lysine	4,4	4,0	5,7	5,1	6,8
Met + Cys	3,6	3,5	3,0	3,2	2,9
Phe + Tyr	9,6	9,8	8,4	8,6	7,4
Threonine	3,9	3,9	4,6	4,0	4,5
Tryptophane	1,2	1,3	1,0	1,3	1,4
Valine	6,6	6,8	6,9	6,3	6,3
Chemical score	76b	69b	76a	87a	79a
Proteins	7,8	7,2	16	15,8	25,3
Proportions by weight	100	92,2	2,2	3,4	2,3
Distribution of proteins	100	82	4,	6,5	7,2
Tryptophane

A 100% = 3,76 g Met + Cys/16,8 gN
B 100% = 5,78 g Lys/16,8 gN
Source: IRRI

Brown rice has 1,8 – 3,9% lipids, concentrated in the aleuron and embryo. Most is in the bran; polished rice contains only 0,3 – 0,7% lipids. These are used industrially (a.o. rice oil for animals and soap products).The mineral value of rice is another factor which is adversely affected by milling, see Table 1.3.

Table 1.3 - Mineral value of rice, mg/kg

	Brown rice	White rice
Calcium	32	24
Phosphate	220	94
Iron	0,16	0,08
Sodium	9	5
Potassium	214	92
Zinc	0,26	0,12

Source: IRRI

There is not much iron, and half is in the part removed by milling. The ratio between calcium and phosphate is not ideal; the phosphate is found mainly in the form of phytates. The level of vitamins A and D is negligible, although there is a great deal of vitamin E. There is little riboflavin (0,6 mg/kg in brown rice), and virtually no vitamin C, but there is ample thiamine (3,4 mg/kg of brown rice) and niacine (52 mg/kg of brown rice) as well as pyridoxine and panthotenic acid. An average serving (6 oz) of cooked rice gives enough energy to walk for 45 minutes, because it contains 345 kcal per 100 kg, which is almost identical to wheat and maize (340 and 342 respectively). This is for 100 g of dry rice, of course, and after cooking rice triples its volume. 100 g of cooked rice contains 120 cal, 3 g of proteins, 0,1 g of lipids, 0,01 mg of thiamine and 3,4 g of niacin. Bran and ‘polish’ together contain about 85% of the oil, 10% of the protein, 80% of the thiamine (B1), 70% of the minerals and fibre, 50% of the riboflavin (B2) and 65% of the niacin of the whole grain. White rice is 90-94% pure starch and when highly polished contains only 7% protein by comparison to 10% for brown rice. Based on 100 g portions, the caloric content of cooked rice is 111 for brown rice, 109 for regular milled and 106 for parboiled. Rice is a complex carbohydrate, supplying energy over long periods. Another important function of a dietary carbohydrate is energy sparing – the body does not use protein to meet energy needs when a carbohydrate is available. The protein content of rice is of good quality because it contains all the amino acids necessary for human life; it contains only a trace of fat and is cholesterol free; it is non-allergenic and gluten-free, and is very low in sodium. Rice starch is almost completely digested, and between 65 – 88% of rice proteins are digested, depending on how adult the person is – children do not absorb rice proteins as effectively. A number of studies have been carried out on the optimum addition of proteins to a predominantly rice-based diet, and in general it appears to depend on the type of rice being consumed so that general indications are hard to draw.

As a food, it contains all the carbohydrate that individuals need in their diet, being 90% carbohydrate itself/ Dry rice produces 3,5 kilocalories per gram, compared with 8 kcal for a gram of fat. Rice is a good source of various B group vitamins such as thiamine (B1) which helps control various body functions, the human nervous system, and also contributes to healthy skin. B group vitamins are water-soluble and cannot be stored in the body; therefore a regular intake is essential. Natural brown rice is an excellent source of dietary fibre which performs many vital functions within the human body; it eases the disposal of waste products and is also easily and quickly digested, making it especially suitable for athletes, babies and the elderly.

Most specialist doctors believe that the fibre in foods like brown rice plays an important role in prevention of diseases such as diabetes, heart disease and cancer of the colon. In the past, fibre was thought to add bulk to food but to have little other benefit. Now it is widely recognised that it is a far more complicated substance and is not digested by human beings. The indigestible fibre passing through the bowel can reduce the amount of fat absorbed by the body from fatty foods. It can also help slow down the rise in blood glucose after a meal, particularly beneficial to people within diabetes who need to control their blood sugar levels. Brown rice however, takes up to 40 minutes to cook, compared to less than ten for milled white rice, which is inconvenient for many people.

Rice does, however, provide insufficient protein on its own for a healthy diet. Moreover, the loss of real food value caused by the milling process makes it little short of a world tragedy that the preferred consumption of rice is in its milled, white, highly polished form, when it is easier to eat and quicker to cook. Malnutrition, especially in infants, causing protein deficiency, beri-beri, iron and zinc deficiency, is common in countries where rice forms an overwhelming percentage of the population’s diet. Beri-beri has increased since the increase in use of mills, and was common in Thailand in the 1970s. It is only the increased income of the country in general that has led to alternative foods being available in that country since then, which has cut the problem dramatically. Adding riboflavin to rice causes discolouration, which has dissuaded Far Eastern eaters. There is clearly a need to increase the supplementary elements to a rice-based diet, for example meat, milk, eggs and above all fish, and vegetable oils; to increase the amount of parboiling, and of brown rice to be eaten.

Malnutrition problems are actually exacerbated by the introduction of efficient mechanised units due to the more efficient milling. One way of avoiding the loss of nutrients during milling is first to parboil the raw paddy rice. Parboiling involves transferring the proteins and vitamins from the bran layers to the white central part of the seed, by steeping the paddy in hot water, steaming it and drying it before milling. This procedure gelatinises the starch in the grain, and ensures a separateness of grain. Parboiled rice is favoured by consumers and chefs who want a fluffy, separate cooked rice. It retains more nutrients than regular-milled white rice, but takes a few more minutes to cook.

It is possible to restore valuable nutrients after milling by adding solutions of thiamine, niacin, iron and riboflavin. Enriched rice has greatly helped to improve the problem of malnutrition in many rice-eating countries. Rice is a very palatable cereal; the only one which can simply be boiled and eaten without degenerating into mush.

1.3 Food and animal feed uses

Rice is used almost exclusively for human consumption; hardly any is used as animal feed. In all Asian countries, China, India and Bangladesh in the East and Japan and Korea in the South, rice is the most eaten cereal by far. Average annual consumption is about 100 kg per person with a wide variation between countries. In Vietnam it reached 240 kg per person in the 1980s. In Laos and Thailand 202 kg, in Bangladesh 160 kg, whereas in the Philippines it was 89 kg, in India 73 kg and in China estimates vary from 72 – 96 kg/person. The variations are accounted for by the use of other cereals. These levels compare with 4 kg annually per person in France, for example.

The types of rice in which each market is interested vary enormously, which is a factor of great significance for the international rice trade itself. Sadly, much of this trade involves shipping rice to countries that already grow it because the national tastes do not suit the particular type grown.

Two very good examples of this practice are the export of round grain rice from Italy and the import of long grain rice; and the import of fragrant Thai rice into California. In both cases, domestic rice production is slowly changing to meet the changes in demand, but it must be realised that the types of rice demanded can vary so much that one form of rice can be completely unacceptable to one market. For example, the Japanese market, at least for the time being, prefers white short grain rice, recently milled, of a japonica variety. The Thais, by contrast, prefer a well-milled rice, stored for some time, of a long grain indica easily separable variety.

Again, Middle Eastern consumers prefer long grain rice with a strong taste, whilst Europeans prefer tasteless long grain rice. Africans prefer broken rice, especially of the red tinted type. Bangladeshis prefer parboiled rice which is easily cooked. One regrettable but abiding fact is that brown rice is little appreciated in tropical countries. In hot countries brown rice keeps badly, but the real reason is that brown rice symbolises poverty in these countries, people try to avoid it, and it is considered inappropriate to serve it to guests.

Unlike other cereals, rice is usually presented to the consumer in its raw form, so it is according to visual criteria that rice is judged – the length of the grain, the degree of whiteness, the translucence, the proportion of broken grains and so on. The EC distinguishes four types of rice on the basis of the ratio of the length to the breadth of the grain, see Table 1.4.

Table 1.4 - Grain types

	Length, mm	Length to width ratio
Round grain	5,2	2
Middle grain	5,2-6	3
Long grain A	6,6	2 - 3
Long grain B	6,0	3

Source: ONIC

The cooking qualities of rice are largely determined by the relative quantities of amylase and amylopectine in the starch and to a lesser extent by the level of proteins and the temperature of gelatinisation. The more amylase, the better the rice stays apart when cooked. Less than 20% between 20 – 25% and 25 – 36% are the three classes in this matter. Indica rice consumers in India, Pakistan, Bangladesh, Malaysia and South China prefer varieties high in amylase, i.e. a ‘dry’ rice after cooking, whereas in the Philippines and Indonesia, intermediate levels of amylase are preferred, and the Japanese and North Chinese choose ‘sticky’ rice. In North Thailand and Laos, glutinous rice is preferred. Parboiling, practised largely in India, Bangladesh and Sri Lanka, produces a further set of distinguishing characteristics largely appreciated in those countries only. It is however, worth adding that in western countries a growing appreciation of all types of rice is now occurring, and even Thai fragrant rice can now be bought in the average British supermarket – an extraordinary change from the 1970s when only long grain US rice was available, apart from short grain rice contained in deserts.

Rice is now eaten in almost every country in the world. For example, it is used in Spanish paella, the popular US dish of jambalaya and with curry in virtually every Asian country and the U.K. Rice is also eaten toasted or coated with sugar or chocolate as a breakfast cereal. Rice can be eaten on its own, or coloured with saffron or turmeric, or flavoured with herbs and spices. For example, pilau rice is made by adding peppers, stock and onion. Rice is also used to make powerful alcoholic drinks, for example, saki (Japan) and wang-tsai (China) come from rice. Almost one-third of the rice used in the USA goes to make beer.

Rice must be cooked before the human body can absorb the starch. There are basically four ways in which rice is cooked: with just enough water, by boiling in a large quantity of water and draining, cooking in fat (as with paella, risotto and pilaff) and steaming. The temperature necessary for cooking rice depends on the starch and protein composition of rice: ordinary white rice takes about 16 minutes to cook (less in a microwave oven). Rice increases in size from 100 kg to 230 – 240 kg after cooking. This capacity for retaining water actually poses a problem for infant nutrition: the infant stomach can retain only 180 ml at 2 years, so to get 1000 kcal of energy, it would be necessary for the infant to ingest about 1 kg. However, it is possible to reduce this absorption by introducing other cereals into the cooking. To reduce the time taken in cooking, pre-cooked rice has been put on sale, which has reduced cooking time to only a few minutes.

Ground rice flour is used to thicken sweets and sauces, and to replace wheat flour in the diet of people who suffer from food allergies. Wheat flour loaves are often dusted with rice flour before baking, and powdered rice is used in some developing countries to make noodles, cakes and sweetmeats. Rice paper is also used to cook cakes and sweets such as macaroons; rice bran is used for animal feed. The stubble from rice is ploughed back. The straw is used for making hats, shoes, ropes, mats and for thatching. The surplus straw is used as animal fodder and bedding. Rice husks, removed by milling, have little nutritional value but they are very rough and contain silicon, which is useful as an industrial abrasive. The husks are used as fuel in village stoves, as insulation, for making lightweight brocks and as a packing material. New uses are constantly being researched for the 75 m tonnes of husks produced every year. Rice is also used for starch production, glucose, rice vinegar and rice oil.

By contrast, the bran has a very high nutritional content. It can be refined to make a fine, clear oil, low in fatty acids, which is good for cooking and for protecting industrial machinery from rust. Broken rice is bought by brewers, who use it to make liquors such as saki and arrak. Whole and broken rice is used for making starch. Tinned pet foods and sausage fillings often contain a percentage of broken rice. It is evident, then, that rice has a variety of nutritional, feed and other uses, vital to the lives of billions of rice consumers across the world. It is important to realise how essential rice is.

1.4 Rice qualities traded

Paddy: usually with a guaranteed milling yield such as 55 – 68 meaning that out of 100 kg of paddy the miller will obtain after milling 55 kg of white grains and 13 kg of broken grains, giving a total yield of 68 kg. Only a few countries, notably the USA, export their paddy rice.

Brown (dehusked): usually required by the rice industry with a guaranteed yield, e.g. US 2/4/73 – 73% whole grain, 12% bran and 15% brokens.

Some commercial rice mills are in the rice producing countries such as Indonesia; others are in the rice consuming countries, including Britain and Holland which import raw paddy for their mills. Of milled rice, the most widely traded qualities are:

White:

• US milled No. 2/4 long grain (grade 2/4% brokens) to Europe/Middle East/Latin America
• US milled 5/20 LG (grade 5/20% brokens) in US foods aids
• Thai White Rice 100%B (4,5% broken maximum) to Middle East (Iran/Iraq), Malaysia
• TWR 5/10/15/25/35% brokens
• Broken 100% either for human consumption or as animal feed
  
  

Parboiled:

• Thai parboiled 5% brokens to Benin/Nigeria/Bangladesh
  
  

Most of rice moving in world trade is fully milled and bagged. Packaging requirements in contracts may be anywhere from a shipload full of bulk (loose) rice to 1 kg retail boxes, but 50 kg (or 100 lb) bags being common sizes. The international rice trade is under a quarter of that in wheat, which trades almost 20% of tits world production. However, in value terms the rice trade is closer to wheat – approximately one quarter – about half of the sugar trade and almost as much as the cocoa trade.

1.5 Definition of 'rice'

‘Rice’ shall mean: rice, rice products, and rice by-products. It shall include: milled rice, brown rice, undermilled rice, parboiled rice, pre-cooked rice, rice flour, rice bran, rice polish, rice hulls, rice mill feed, and any other rice products or by-products.

The rice trade

Recent statistics show a total amount of rice traded globally was 23 million tonnes. The ratio of trade volume, against a total production (340 million tonnes of milled rice base) is approximately 6,5%, which is significantly less than other grains.

Rice production in Vietnam is about 34 million tonnes (paddy base) where the main production areas are the Mekong Delta in the South and the Red River Delta in the North. The Mekong Delta produces more than half of the country’s total production and provides suitable climate conditions where in most cases farmers can harvest rice more than 3 times a year.

Rice harvests are generally between February and March; July and August; November and December for short time rice; and January and February for long time rice.

2.1 Rice moisture

At harvest, paddy rice has a moisture content of generally between 20% and 28%. Most of paddy varies with maturity, whether it is rainy or dry season, and atmospheric humidity. The moisture content of paddy can very and is understandably higher in the wet season than in the dry season.

Paddy rice should be dried to a moisture content of less than 20% within 48 hours of harvest to reduce the chances of damage. To facilitate good storage, it is best that the paddy rice is dried in the sun or with modern drying techniques and/or machinery to a moisture content of 14% or less.

Rice kernels should have a moisture content of between 13% and 14% to ensure good storage. When the moisture level exceeds 14%, the rice takes on a yellowish hue that can lead to mould, lumping and decay and can result in damage affecting both the quality and quantity of the rice.

The damaged rice can affect undamaged rice in close proximity but not necessarily in direct contact, particularly when bagged and awaiting shipment. Therefore it is prudent to check for this type of damage prior to the cargo leaving the warehouse storage facility.

In order to do so, the carrier and their appointed surveyor require the full cooperation of shippers to identifying where the rice is being stored prior to shipment.

The favourable travel temperature of rice is 5 – 25°C. The optimum temperature for the development of moulds is between 20 and 30°C. Travel temperatures of >25°C increase metabolic processes and thus self-heating and agglomeration (sticking together).

2.2 Milling and processing

Rice processing is the most essential stage of the post harvest activity where husks and bran particles are removed from the paddy grain. Milled rice maintains a higher temperature than that prior to processing. Generally, at this stages the moisture content is higher than 14% and particles of bran adhere to the surface of the kernel. Since the rice has generally been whitened, it soon takes on an ivory or yellow coloration.

2.3 Preparing rice for export

World trade figures are very different, as only about 5–6% of rice produced is traded internationally. The largest three exporting countries are Thailand, Vietnam, and the United States. Major importers usually include Bangladesh, the Philippines, Brazil and some African and Persian Gulf countries. Although China and India are the two largest producers of rice in the world, both countries consume the majority of the rice produced domestically, leaving little to be traded internationally.

Thailand will continuously lose competitiveness and export market share to Vietnam in Asean and other markets over the next 10 years due to that country's clearcut policy of developing its rice production and marketing, according to a report by the International Trade Studies Centre.

In 2020, Thai rice exports to the world market are projected to drop by 14 per cent from this year's level to 8.6 million tonnes, while Vietnamese exports will surge by 25 per cent to 7.5 million tonnes.

Prior to the 1990’s Vietnamese rice exports were considered low grade where on the order of 35% of exported rice had broken ends. Following significant improvements in production and processing technology, Vietnam can produce rice with between 5% and 10% broken ends.

There is a Vietnamese Rice Standard for Export that was established by the Standardization Meteorology and Quality Control (SMQC) Centre. Foreign buyers can require the Vietnamese standard or request their own export specifications. The following steps are indicative of how local exporters prepare rice for export:

• Milled rice is purchased from local mill/merchant
• The rice is processed and/or classified according to the grades and standards for export. Cargo is separated into separate piles according top grade and quality.
• Adjust the rice quality, if necessary, to meet the specifications of the shipments by reprocessing (via whitening, sieving, polishing, drying, etc.) or simply by mixing rice of different quantities from separate piles in ratios determined during packing at the warehouse.
• Bagged rice is transported from warehouses and remote locations in and around Ho Chi Minh City and throughout the Mekong Delta area. This point makes if difficult to monitor the rice accurately.

2.4 Notable problems

Most rice exporters, sellers and shippers allocate quantities of cargo for one-day shipment to several supplier warehouses in Ho Chi Minh City and/or Mekong Delta provinces. Since these suppliers do not necessarily export directly, each supplier is solely responsible for their cargo until loaded into the ship. They then try to profit by supplying cargo just meeting the lower margin of the required specification and at times, slightly out of specification.

In addition, many suppliers buy rice from local farms, mills or merchants as needed due to lack of adequate finances to buy and process rice in advance of export. When cargoes are needed urgently for export, the rice cannot necessarily be processed in time resulting in compromises made with the cargo quality. This can result in compromising the cargo quality and, in particular, exceeding the necessary moisture content.

As mentioned earlier, the Vietnamese Government Standard for average moisture contents is 14%. This can easily be complied with by mixing rice kernels of higher moisture contents (e.g. 14,5%) with rice of low moisture content (e.g. 13%) at a ratio that makes the overall content meet the required government standard. However, the effects can be damaging during transport that leads to mould, discolouration and decay. It not only affects rice in close proximity, but other rice within the hold leading to moisture migration, smell, taint and heating of cargo. Damp rice kernels spoil undamaged rice in the immediate vicinity.

It is therefore important that, weather permitting, cargo and holds are adequately ventilated.

The problem of exceeding the moisture content is compounded during the country’s monsoon season between May and November. Moreover, to meet Vietnamese government specifications, many small suppliers and warehouses simply adjust the quality of rice by mixing it with rice from different quality, grade and moisture content during the packing operation. This method is acceptable for some contracts of quality such as meeting the percentage of broken kernels, red kernels, yellow kernels, paddy, etc. but is problematic when it neglects the moisture content of the rice.

While techniques in drying and processing rice have improved significantly over recent years, there are many loop holes in the system that allow poorer qualities of rice to be shipped with rice that meet quality standards.

Circumstances at the load port

It is normally the case that the ship’s holds are examined prior to loading by cargo interests. Shipper’s surveyor will normally request that a hose or preferably an ultrasonic test of the hatch covers is conducted. Ships’staff should cooperate fully with such requests.

If the ship is approved to load, then dunnage (timber or bamboo) will be placed on the tanktops of each hold. This is normally in the form of timber planks of cross sectional dimensions 6”oximately) which are laid longitudinally in a fore-and-alignment on the tanktop. Thereafter, kraft paper, or plastic sheeting will be laid on the top of the dunnage. (in some Vietnamese ports bamboo poles and matting are substituted for the timber and kraft paper/plastic sheeting, such as outlined under item ’4.1 Dunnaging’.

The objective of this is to separate the bags from the steel work of the holds in order to allow an air gap to:

1. Permit ventilation
2. Uplift the lower-most bags from the steel tanktop such that if condensation forms on the latter, it will not be in contact with the cargo and thus prevent wet damage.
3. Allow a drainage space for the condensation to flow aft to the bilge suctions.

This specification of protecting the bags does not achieve its intended objective as in between the planks the cargo will be separated from the hold tanktop steel plates by merely the thickness of the kraft paper or plastic sheeting. In this scenario, any formation of moisture from whatever source will almost certainly result in wet damaged bags above and such moisture will not be able to flow aft to the hold bilge suctions. What is needed is a cross pattern of stout timbers, the lower planks arranged fore and aft and the upper planks transversely. Thereafter the upper planks should be covered in either kraft paper or plastic sheeting before loading commenced. Similar arrangements should be arranged to prevent contact of the bags with the steelwork of the hold at the sides and fore and aft ends of the hold.

This of course is an expense for the account of shippers and/or charterers, which they will usually attempt to avoid. Often an inadequate degree of dunnaging (i.e. one tier of planks on the tanktop fore-and-aft) within a ship’s hold has been consistent with initiation/aggravation of wet damage. Masters should formally complain to Cargo Interests/Charterers with a letter of protest when inadequate dunnaging is provided.

Condensation during the voyage to West Africa will often occur as the ambient air temperature and the sea water temperature reduces. Additionally, day and night time air temperatures differ substantially more in non-tropical regions than in tropical regions. This will promote condensation if proper ventilation is impossible. Additionally, when the ship rounds South Africa and passes from the warm southern Indian Ocean waters into the cold Southern Atlantic Ocean waters there will be a substantial drop in sea water temperature. This cooling effect will also promote the development of condensation.

The solution is adequate ventilation and the provision of an air gap between the hold steel work and the cargo and adequate ventilation channels within the cargo stows. Most of the ships however, have no mechanical means of ventilation. It is known that some carriers elect to open the hatch covers during the voyage as much as possible and when conditions permit. It is not the intention of this book to discuss in detail when and how to ventilate cargo holds as the sciences is well established and accepted in the industry.

Many claims in West Africa concern wet damaged cargo to varying degrees in the lower tiers in every hold cause by condensation arising out of the factors outlined before. In most of such cases, locally appointed cargo interest’s surveyor insisted that irrespective of the fact that tiers above the lower most tier in each hold were in a sound condition, the wet damage to the lower most tier could only have been caused by sea water ingress via the hatch covers. Clearly, this is an irrational and unsustainable argument which can be defended albeit at considerable cost both to the ship owner’s P&I interests and to cargo underwriters. Most of these problems and costs can be avoided merely by adequate separation of the cargo from the hold steelwork and by the methods mentioned above.

It is in the interests of cargo shippers, receivers, charterers and the shipowners, that the minor additional expense of providing adequate dunnaging to the tanktop and ship’s sides during loading, as noted above, would considerably reduce cargo damage claims and survey costs incurred in investigating same.

Loading rice

Vessels customarily load rice cargoes at mooring buoys or anchorages in and around the port of Ho Chi Minh City. Bagged rice can be transported by truck from inland points or directly into wooden or steel barges and delivers the rice alongside the vessel. Cargo can be exposed to wetness damage during the barge leg of the voyage due to water ingress via the barge hull planking from older wooden barges or via the deck/hatch cover arrangements of both steel and wooden barges. This is a particular problem during inclement weather.

Cargo is loaded aboard using port stevedores who are not usually contracted by the owner but by the shipper and/or charterer. Experience has shown that little or no attention to detail or care is shown to loading the cargo since the stevedores are poorly paid for their work.

The use of steel hooks to load bagged rice is generally prohibited. However, this practice is still used and unless challenged will go on unabated. The consequences of such actions can result in damage and loss of cargo through spillage that doesn’t become evident until cargo is discharged. At many West African ports where rice is discharged, receivers are often claiming that the bags and contents are damaged, even if the cargo is sound but the bag has but a small cut no longer than say 1 cm long. Clearly, if stevedores use hand hooks, then every bag perforated by such a hook during loading will be deemed damaged at the discharge port.

Hence, the Master must issue letters of protest to cargo interests, the mate’s receipts should be suitably claused and the agents given written instructions only to sign bills of lading in accordance with the clauses on the mate’s receipts. Additionally, many good photographs should be taken and made note of date, time and specific location, and also what the problem is that the photograph is attempting to portray. Such evidence is extremely valuable for Owner’s P&I club surveyor when attending at the discharge port.

It is not uncommon to see stevedores urinating in or on cargo in underwings and secluded corners of the vessel. Experience shows that the stevedores care little for safe stowage and dunnaging and building of ventilation channels in the stow that provide adequate ventilation of cargo. Consequently, shipowners, charterers or receivers will arrange for separate stevedores to arrange and lay appropriate dunnage.

Lowering heavy slings or drafts of cargo too fast on to cargo already in stowage may be responsible for damage, which often goes undetected until discharge. Similarly, forcefully dragging cargo out that is wedged by other cargo or even overstowed, may be another source of damage at the time of discharge. The use of cargo hooks may be indispensable in the handling of a large variety of break bulk commodities, but with bagged cargo the use of cargo hooks may be productive of much mischief and claims, and should be strictly prohibited.

It is recommended that shipowners arrange for independent surveyors to ensure proper stowage, care of cargo during loading. It is also recommended for ship’s staff to conduct initial, intermediate and final draft surveys to reduce chances of cargo shortage claims. Ensure that owners have appointed an independent firm of tally clerks and that there is one at each hold tallying the cargo during loading. It is unadvisable to rely on charterers’ tally clerks. From time to time ships’ staff should check that the tally clerks are correctly counting the bags loaded. There is a practice at both the loading and discharge ports for tally clerks to count only the net slings loaded into the ship assuming that each has the ‘standard’ number of bags loaded into the sling. This may not be the case and often this is not the case in West Africa during discharge.

Where applicable, the hatches should be sealed upon completion of loading in the presence of the shippers/charterer and unsealed at the discharge port, in the presence of the receivers/charterer.

Ships’ staff should record details of superintendents attending the vessel, who they represent and record their loading instructions. If Charterers appoint a superintendent ensure that the ship retains an original copy of Charterer’s loading instructions. If the Master is in any doubt he should take advice from his owners and express that doubt in a letter of protest.

Ship’s staff should ensure that the cargo is tested for moisture content. The maximum humidity content for rice to be shipped is accepted as 14%, above that figure any problems can be expected at the discharge port. Obtain cargo quality certificates but do not rely upon them. If at some Asian ports where rice is loaded, a government inspector can be physically threatened by cargo interests for attempting to reject wet bags, then cargo interests are capable of producing cargo quality certificates which state what is in their best interests and which may have little relevance to fact. The agent may not be the best person to approach in obtaining such analyses as his allegiance is very likely to be with Charterers. Masters should approach the P&I club local correspondent for such advice, or via his owners, the club directly. It is frequently the case that the load port ship’s agents are appointed by charterers upon the recommendation of shippers.

If the cargo is loaded from barges it is essential that ship’s officers go down into those barges and check the cargo for signs of wetness before each and every barge commences discharge to the ship. Any bags showing signs of being wet or having wet contents should be rejected and if necessary joint samples taken with cargo interests for humidity analysis. Those analyses should not be done at a laboratory customarily used by cargo interests, the laboratory needs to be entirely independent and the local club correspondent will be able to advise which laboratory would be most appropriate for this work.

If rain is likely, instructions should be obtained from the shippers and charterer and weather watchers should be appointed. The Master may also be able to use the radar to predict any forthcoming rain showers. There should be enough crew on board to close the hatches if rain is expected. In certain conditions and ports, hatch tents can also be erected to ensure the maximum possible protection of the cargo during loading.

Rain letters
Some charterers issue a ‘rain letter’, which supposedly provides an indemnity against the consequences of carrying out loading operations in the rain. There are several problems associated with this. Firstly, the cargo being loaded and the cargo already in the cargo space may be directly wetted by rain and suffer damage. Secondly, the rain will raise the moisture levels in the hold, leading to a substantially increased risk of condensation and damage to the cargo. There is a prospect that if a rain letter is issued and accepted, and cargo damage occurs as a result of loading in rain, P&I club cover could be prejudiced as a result of the Member deliberately carrying out cargo operations in circumstances where they know cargo damage may occur. In that case the owner may have to rely on the rain letter instead of his normal P&I club cover. Where there is evidence that condensation may have caused the problems, some charterers try to argue that any resulting cargo claim is the owners’ fault, arising out of failure to properly ventilate the cargo, forgetting the part they may have played in creating the conditions that led to the condensation. Hence, the use of rain letters should be avoided.

4.1 Pre-loading hold preparations

Hold washing
Prior to vessel’s arrival at the port of loading, the holds should be cleaned of all previous cargo residues and water washed. If possible, the water used should be fresh water only. It is normally the case however, that ship’s staff wash down the holds with sea water and when cleaned, the steelwork is rinsed down with fresh water. The latter should be a thorough operation as it is imperative that all chloride residues are removed after the sea water wash. If not, and if condensation forms during the voyage, and that condensation is present at the discharge port, this is likely to be tested by cargo interest’s surveyor by simple chemical tests to detect the presence of chlorides (silver nitrate). The results are likely to be positive if there are residues of chlorides from the seawater wash and cargo interest’s surveyor will readily, and happily conclude that such evidence proves that seawater ingressed the holds during the voyage. Additionally, the presence of chlorides and moisture create ideal conditions for mould growth.

Ballast tanks
The double bottom ballast tanks and top-side ballast tanks (if any) should be pressed up prior to loading to ascertain watertight integrity.

Bilge suctions and tanktop openings
These should be thoroughly examined, tested and proved fully operational and the strainer plate over-covered with burlap. Bilge wells should be opened and cleaned. Any openings into the tanktop should be examined and proven to be watertight and properly secured.

Sounding pipes and other hold pipes
These should be examined and cleared of any debris. Any pipes within the holds, including ballast pipes or tank air pipes should also be closely examined and ensured that they are in good condition. Ensure that sounding pipe closures on deck are watertight.

Hatch covers
These should be examined and hose or preferably ultrasonically tested and proven satisfactory. The hatch cover test should also extend to the hold access covers and any deficiencies corrected.

Hold ventilation
Ensure that the ventilation shafts and flaps are in sound condition and the flaps operable and capable of weather-tight closure. In the event the vessel has mechanical ventilation ensure that it is services and in good operable condition.

4.2 Tightness of hatch covers

Approximately one third of all P&I claims are cargo-related. A significant portion of cargo claims is caused by water damage, of which numerous cases relate to ingress of sea water via the hatch covers of dry cargo vessels. Reports of leaking hatch covers are the most frequent cause for selecting a vessel for an unscheduled condition survey.

In sailing vessels the cargo hatches used to be small, as small as possible, in order to preserve the integrity of the hull. Decks were often awash during ocean passages and the smaller the opening, the smaller the risk of flooding the holds. In the ships of today the cargo is no longer carried on board on the backs of strong men, and the speedy loading and discharge methods require much larger deck openings. Very large openings actually, but manufacturers have been able to design and build strong enough steel covers and closing devices to cope with the demand – strong enough and tight enough at the time of testing and delivery of the new ship, but as the vessel ages, however beautifully, the hatch covers are prone to suffer from wear and tear, and problems of tightness arise.

When leakages occur, ship managers may blame weather conditions rather than possible lack of maintenance of hatch cover tightness systems. One will often find, however, that there is evidence of both: bad weather and poor condition of hatch cover tightness systems.

A carrier’s liability for cargo damage relating to sea water ingress via the hatch covers often depends on whether he can demonstrate that he exercised due diligence to make the vessel seaworthy before and at the beginning of the voyage in question. Whilst this is an onerous burden of proof to meet, a carrier who can show diligent procedures and practices with regard to inspection, testing and maintenance will be less likely to encounter problems from the outset, and will be better placed to show that due diligence has indeed been exercised. Hence, good maintenance and proper testing of hatch covers is a clear loss prevention issue.

In the following paragraphs we look at some major points related to the tightness of cargo hatch covers of dry cargo vessels.

Law and order
The 1966 International Convention on Load Lines contains regulations on the position of hatchways, height of coamings, strength of covers and the need for securing devices. These regulations have to be complied with for the issuance of an International Load Line Certificate. Flag states normally authorise the vessel’s class society to carry out inspections and to issue various certificates on their behalf, including the Load Line Certificate.

In addition, the class societies have rules for the construction of hatch coamings and hatch covers, and these have to be complied with in order to obtain a Classification Certificate covering the vessel’s hull.

Hatch covers are inspected annually, by a class surveyor, for the purposes of the two certificates mentioned above, so class societies have a major influence on the degree of hatch cover maintenance needed as far as certification is concerned. The responsibility for maintaining vessel’s hatch covers and locking devices lies with the owner and operator, but class and flag state are responsible for certifying compliance with classification and load line rules. Also, SOLAS regulations for the issuance of an International Cargo Ship Safety Construction Certificate touch upon the subject, and require openings on deck to have the means to be watertight.

The purpose of the International Safety Management (ISM) Code is to provide standards for the safe management and operation of ships. Its requirements include the creation of procedures for maintenance of the vessel and for inspections and reporting. When checking the text of such procedures, surveyors often see that not much attention is paid to the vessel’s hatch covers. The hatch covers are important to the safety of the vessel, crew and cargo, but are often addressed in very general terms only, or hardly mentioned in the vessel’s maintenance procedures. Members are strongly recommended to include instructions from hatch cover manufacturers in the vessel maintenance program, including records of maintenance, tests and repairs.

Weathertight or watertight ?
The International Load Line Convention contains principles for assigning minimum freeboard to ships: limits to how deep vessels are allowed to be loaded to perform a safe voyage. It also includes regulations on how to construct and equip vessels to avoid ingress of sea water through various openings. It addresses primarily the safety of the vessel, not the safety of the cargo. The convention requires hatch covers to be “weathertight”, which may lead to arguments on how tight the hatch covers really need to be, as the word “watertight” is not used. However, the Load Line Convention itself states that “weathertight” means that in any sea condition water will not penetrate the ship.

Surveys for the issuance and maintenance of the class and statutory certificates do not always seem to be sufficiently strict to ensure that the cargo carried is safe from the ingress of water through the hatch covers. A few tons of water into a cargo hold may not represent a risk to the safety of the ship, but even very small amounts of water may for instance damage a sensitive steel cargo. Class surveyors are not particularly trained to care for the cargo, with the result that cargo hatch covers approved during a load line inspection may fail during a P&I condition survey. Class Societies have had different rules concerning the frequency of hatch covers tests in the past.

According to the International Association of Class Societies (IACS)’s publication Care and survey of hatch covers of dry cargo ships – Guidance to owners, a special survey “shall, as a minimum, consist of checking the effectiveness of sealing arrangement of all hatch covers by hose testing or equivalent as necessary”. But how does a surveyor know if a hose test is necessary? It is certainly necessary to test hatch covers much more often than every five years, for the safety of the cargo, and class societies should encourage surveyors to do that. A recommendation to carry out a hose test of the hatch covers “as necessary” gives surveyors some freedom to omit the test when faced with practical difficulties (e.g., loaded vessel when no ultrasonic testing apparatus is available) and to carry out only a visual inspection.

Hatch cover problems
When hatch covers are leaking, the rubber gaskets are the first to gain attention. Rightly so, because many problems are directly linked to their condition, and the crew may be able to change the gaskets themselves. Regrettably, however, some owners limit hatch cover attention to replacing the gaskets when worn out, and miss out on many of the finer points of hatch cover maintenance. Most hatch covers have movable parts like hinges, hydraulic cylinders, wheels, cleats, toggles, all exposed to wear and tear over time and having an influence on how well the hatch covers work. Also, corrosion and physical wear of fixed parts of hatch coamings, hatch panels, storage racks, etc., may lead to leaking hatch covers. Due to the frequent operation of the covers and the loads and forces they are exposed to, vessel’s hatch covers will age faster than the ship, and will need constant maintenance or major renewals during their lifespan. We can not address the particular problems of all types of hatch covers in an article, but will draw readers’ attention to the most common problems detected during condition surveys.

Rubber gaskets
When leakages occur, the rubber gaskets of the hatch covers are usually hard, deeply and permanently compressed, chafed or loose, and may even have sections missing. Gaskets may be of solid rubber, or have a hollow or sponge core. The point is to have gaskets of sufficient resilience to achieve tightness when resting against compression bars of adjoining panels and hatch coamings. The design compression for common gasket types is usually in the range of 10-15 mm, depending on the thickness, and a manufacturers’ rule of thumb is to replace the packing when a permanent impression reaches half the design value. This may seem a hard rule to live by for many superintendents, but that is how to avoid leaking hatch covers in bad weather. Surveyors often see hatch cover gaskets with permanent depressions around one third of the thickness. Such gaskets should definitely be replaced. When replacing gaskets it is important that the retaining channels be in good condition and maintained against corrosion. It is recommended to use original gaskets and to seek the hatch cover manufacturer’s advice. There are a lot of low quality rubber gaskets on the market. Cheap rubber gaskets will rapidly become permanently compressed and the loss of resilience may cause lack of tightness after a few months of service. When buying original rubber gaskets, the best price is normally obtained directly from the hatch cover manufacturer. Ship managers often leave the job of replacing the gaskets to the crew, with a variety of results. It is certainly cheaper than doing the job in a shipyard, but in all fairness the crew can not always be expected to do as good a job. At least some support from a skilled worker or supervisor is recommended. Pre-shaped corner sections should be glued in first and the straight lengths of gasket thereafter, slightly oversized in length. Surveyors often see gaps at joints of gaskets, as lengths are cut too short. Short pieces of gasket should be avoided, as they often fall out later. When gaskets are chafed or even clipped lengthwise by the compression bar, they must be replaced without delay.

Retaining channels
The gasket retaining channels are among the weakest construction parts of the hatch covers. Their maintenance is cumbersome and often neglected, and retaining channels are often reduced by corrosion and are thus not able to provide sufficient support of the gaskets. When gaskets are replaced, one should always use the opportunity to clean the retaining channels for rust and have them thoroughly coated. Retaining channels may be so reduced by corrosion that as the rust flakes are removed the new packing will fit in too deeply. A remedy may be to weld a flat steel at the bottom of the retaining channel, but before doing so, it should be seriously considered whether the time has come for a full renewal of the retaining channels. Heat applied by welding to a weakened steel channel may cause deformations, making tightness difficult. Retaining channels may also have been damaged by contact of grabs, wires for pulling, etc. Damaged corners are often noted in hatch covers of the single pull type on older vessels. Such damage may be a result of panels slamming against each other or against the hatch coaming top, during closing operations.

Steel to steel contact
One thing is fundamental to a good result when changing gaskets, and that is to check the steel to steel contact between the hatch covers and the hatch coaming top. Good and original gaskets may be rapidly damaged by over- compression if this steel to steel contact is not achieved. Surveyors have met superintendents who are satisfied that the hatch covers float on the gaskets alone, and who even damage the gaskets further by increasing the force of the vertical periphery cleats. The full weight of the hatch covers is not supposed to be borne by the gaskets alone, only to the extent that the correct design compression of the gasket is achieved, and then limited by the hatch cover resting steel to steel on the coaming top. For older vessels the steel to steel contact will often be affected by wear and corrosion of the resting pads, or if these are not fitted, by reduction of the lower edge of the hatch covers and by wear and corrosion of the contact area on the hatch coaming top.

The solution is to fit new resting pads of adjusted thickness to achieve a correct design pressure of the gaskets. If that is necessary, the ship manager should consider whether his crew is qualified for the job, or whether it is necessary to go to a repair yard with specialists or to ask the hatch cover manufacturer for support. Surveyors have seen gaskets being replaced by crew every six months due to the steel to steel contact not being correctly achieved.

Compression bars
The compression bars on hatch cover panels and on hatch coaming tops need to be straight and the top edge must be well rounded and have an even surface. On older vessels they often have heavy scales of corrosion, and when the scales fall off in sections, the compression bars are left with high and low areas where compression of the gaskets will be unequal. Such compression bars should be chipped and maintained by coating. On some ships the compression bar consists of a stainless steel bar, welded to the top of a supporting flat steel. Such compression bar is preferred, as the surface stays always smooth and even.

For ship types with expected large movements between hatch covers and coaming while at sea, manufacturers may have designed gaskets not landing on a compression bar, but directly on the flat top of the coaming. For such type it is important that the landing areas are kept free of rust and debris and well maintained against corrosion.

Guiding of hatch covers
When hatch cover panels are placed in position there are, depending on the type, various means to guide them correctly into place. Wear and distortion of items like stoppers, guide rails, track ways, flanged wheels, etc., may allow the panels excessive sideways and longitudinal play and result in the gaskets landing off centre on the compression bars. Worn bearings and bent wheel shafts will also cause a lack of proper guidance for the hatch covers, with the same result. Whenever closing of hatch panels includes “attacks” by crew members armed with heavy crowbars and sledge hammers, something is wrong both with the guiding of the hatch covers and with the general maintenance policy on board. If cargo hatches can not easily be closed due to operational problems, there is also the risk of cargo damage by rain water during times of loading and discharge.

Means of securing
There are various ways to secure the hatch covers once they are in place, depending on the type. Modern covers may be self cleating or secured by hydraulically operated cleats or wedges, but the most common type on older vessels is the manual quick-acting cleat, having a cam at the upper end, which is forced onto a snug on the hatch cover panels. A rubber disc between two steel washers at the lower end of the cleat has enough elasticity for the cam to be placed on the snug by using a portable lever. Thus the hatch covers are restrained from lifting, but are allowed some movement on the hatch coaming in the transverse and longitudinal directions.

Surveyors see a lot of poorly maintained cleats in older vessels, and the common problems are that the cleat is seriously weakened by corrosion or that the rubber disc is hardened and without elasticity. Nuts and treads may be so corroded that adjustments can not be carried out. The snugs, which are welded to the hatch cover panels, may be heavily corroded or damaged, offering no strength to the assembly. A well known problem on ships of some age is advanced corrosion around the passage of the cleat through the hatch coaming top plate. When all such areas of the coaming top plate are weakened, one risks losing the covers under extreme weather conditions.

When hatch cover panels are not sufficiently linked together by hinges, they also need cleats across the cross joints of the panels. These may be in the shape of wedges or screw-cleats. Surveyors often find such wedges to be missing, not engaged or not providing any force on the adjoining panel due to wear or distortions. In the worst cases, all the wedges have been removed and are nicely stored within the forecastle. Some covers may have internal cleats on torsion bars, operated manually or automatically. These are meant to save the crew some work, but when old, such arrangements may not provide sufficient pressure on the cross joint gasket due to wear, and water tightness may possibly not be complete. Such securing arrangements are more difficult to inspect than external ones.

Hatch covers may have distortions making it difficult to achieve watertightness of the cross joints by the original cleating system. Some owners may then choose to install additional cleats, like screw-cleats, to solve the problem, but it is then important to check that the additional cleats closing one joint better do not open the next one. It is always recommended to consult the manufacturer.

High stowing type hatch covers, like the folding type, are sometimes left unsecured in raised position. That represents a danger to the crew and stevedores, and the hatch covers themselves may be seriously damaged if they fall. Securing devices are often seen to be damaged and not functional, or are simply not engaged by the crew. Such mechanical safety devices should always be well maintained and engaged.

Gutters and drainpipes
Gaskets in good condition and regular maintenance and tightness tests of the hatch covers are a must to avoid water ingress into the cargo holds, but in the event that some sea water may penetrate the gaskets during heavy weather, it is important that the water does not enter the cargo hold, but drains out again. Cross-over joints between panels will have gutters fitted underneath the packing to catch small amounts of water penetrating.

These gutters will drain the water to the hatch coaming gutters, and it is important to check that they are not fractured or damaged at the ends, so water drains down the inside of the coamings instead. The hatch coaming gutters will drain the water aft to drain pipes. These gutters are not always well maintained and may have layers of corrosion. They should be kept clean and coated in order to ease the flow of water, and all remains of cargo should also be removed before closing down the hatch covers. Often the inner edge of the gutters, being the top of the vertical hatch coaming plate, may have been chafed by wires, hit by grabs or reduced by corrosion. Such damage will allow the water to overflow to the cargo hold instead of being drained to the drain pipes, and should be repaired and always kept in good condition. The drain pipes aft are often of small diameter, and are easily clogged up. The pipes need to be fitted with a non-return device, in order to avoid that green sea on deck finds its way into the cargo hold through the drains. Non-return valves easily clog up, so that they must either be frequently opened up for cleaning, or it may be better to fit a three-foot canvas hose to the drain pipe instead. The canvas hose must be of a pliable type and be well secured by hose clamps of stainless steel.

Temporary repairs
In older vessels there are often signs of rather desperate efforts to keep hatch covers tight by external taping, and by applying foams and fillers at joints between panels, etc. Rubber liners have been seen glued on top of hardened and worn out gaskets, and tape glued on top of compression bars to build them up to improve compression. On one vessel the crew had run out of tape and tried to improve the watertightness of the cargo hatches by installing a rope covered with cement around the perimeter of the covers. Surveyors have also seen vessels with hatch covers in poor condition being fitted with tarpaulins, pulled down at sides by ropes fixed to any pipe or fittings on deck. Such remedies are often requested by cargo owners or charterers to reduce the risk of water ingress. The master of the vessel may choose such means, if he has doubts about the tightness of the vessel’s gaskets and has a sensitive cargo to carry. All such means are, however, only considered to be temporary repairs, and should not be allowed to replace a fully functional original tightness system. The effects of such remedies are also very limited if heavy weather is encountered. The bonding of the tape is not stronger than allowed by the surface condition of the hatch covers and any firm tightness around cleats, etc., is difficult to achieve. Tape may lose elasticity in cold weather and be ripped off by seas on deck. Tarpaulins will help against sea spray, but will be ripped off if all edges are not firmly wedged in against the coaming. The money spent on expensive tape and fillers could be better used if spent on regular maintenance of the hatch covers and on well planned renewals of the original gaskets.

Tightness tests
There are mainly three different ways to test hatch cover tightness, and they all have some pros and cons. The chalk test is often carried out when the vessel is new, in the shipyard. All compression bars are rubbed with a piece of chalk, thereafter the hatch covers are put in place and secured, and then opened again. If there has been insufficient compression between the compression bar and the hatch cover gasket, there will be a lack of or incomplete chalk marks on such areas of the gasket. The advantage of this test method is that one can see exactly where the problem is. Also, it is clearly seen from the chalk marks if the gasket lands off-centre on the compression bar. The disadvantage is that one needs quite a bit of chalk, which is normally not found on board. The method is rather time-consuming, and it can only be used in dry weather. The hose test is the traditional way of testing hatch covers. It is easy to carry out, and the crew can do the job. It is inexpensive, as a fire hose with a nozzle and good water pressure from the fire pump is all that is needed. It is recommended to perform the hose test regularly between cargoes, to prove hatch covers are in good order. It can be useful to have good results of hatch cover tests entered in the log book. Some of the disadvantages of the hose test are that it sometimes becomes just a lot of messing around with water and it is not recommended to be carried out on loaded vessels – more than once the hose test itself has caused water damage to cargo. Good water pressure is needed, but not always produced, and of course the test can not be used if temperatures fall below zero.

From a surveyor’s point of view, the hose test also has the disadvantage of not being fool-proof: the surveyor will not be able to observe how the spraying is performed on the outside, while he is inside the cargo hold looking for leakages. If a hard water jet is not aimed directly at the hatch cover joints, the test may be worthless. The condition of the hose test can be improved by fitting rags at the outlets from the cross over joints, to contain the water in the spaces between the panels. Another useful trick is to fit plastic bags to the drain pipes from the hatch coaming gutters. If water has ended up in the bags following the hose test, it has passed the gaskets and drained by the gutters to the outlets. Using this method, a surveyor reduces his chances of being fooled by the crew if he chooses to observe the testing from inside the hold.

The latest and most accurate way of testing hatch covers is by using an ultrasonic apparatus. A unit emitting ultrasound is placed inside the cargo hold and the operator registers “leakages” of ultrasound through the hatch covers using a handled detector. Normally one will first measure “open hatch” values and establish 10 per cent of such as the lower acceptable limit with hatch covers closed down. The ultrasonic test method is easily carried out by a hired operator, and the location and importance of leakages are clearly identified in his report. The method has the great advantage that it can also be used on loaded vessels, by placing the transmitter on top of the cargo. Another advantage is that it can be used in cold weather. Major steel exporters may require satisfactory ultrasonic tests carried out on all ships, to reduce risk of damage to cargo. A satisfactory ultrasonic test, correctly documented by the professional operator, will carry some weight if a dispute about hatch cover condition should arise. Nowadays ultrasonic test equipment is available in all major ports, operated either by specialist firms, or by traditional marine surveyors. The only disadvantage with this method is probably that it is not always much liked by all ship managers, as “too many leakages” are detected. There is some truth in that, and the operator and his principals need to exercise some care in judging the results, as even quite small, insignificant “leaks” may be detected. Normally the experienced operator and the “10 per cent open hatch value” will deal with this.

Conclusion
Regardless of method it is recommended to test the vessels’ hatch covers regularly, to watch out for indications of deterioration, and to initiate maintenance early on, ensuring cargo is carried under safe conditions. Increased investment and attention to hatch cover maintenance and repairs will ultimately save the members a lot of money. It is, simply put, good loss prevention.

4.3 Dunnaging

Dunnage usually consists of bamboo sticks laid in a criss-cross fashion on the steel tank tops. These are overlaid with kraft paper sheets and/or bamboo mats. This is similarly laid along the sides of the vessel’s bulkheads and side shell. The problem with bamboo sticks are that they are not free from moisture and retain and bleed moisture into the cargo holds while the ship is in transit. Bamboo sticks may appear dry on the outside but may have a moist pulpy interior.

Though the use of bamboo sticks/matting and kraft paper are seen as the customary dunnaging materials used in loading bagged rice. Nowadays charterers insist on a combination of sheeted styrofoam, polyethene sheets and kraft paper.

While there is no scientific evidence available it would appear this type of dunnage better protects the cargo from variations in temperatures, insulating the cargo from ship’s sweat. One still needs to ventilate!

4.4 Ventilation channels

Ventilation channels within adjacent block stows should be arranged in a manner consistent with the direction of ventilation air flow within the holds. Individual stows should be ‘tied’ together with transversely arranged bags usually at each fifth tier spanning the ventilation channel. It is usually the case that ‘natural’ i.e. non mechanical, ventilation is arranged such that the air flow is fore-and-aft. To ensure proper air circulation, bags should be stowed leaving ventilation channels of 10-15 cm at horizontal intervals of about 20 bags, with individual bags blocking the channels at intervals of 5-6 tiers to ensure vertical strength and stability.

In addition to the above, it is recommended that cargo is placed within the corrugated bulkheads. In this way, the problem of bags falling from the top and bursting, resulting in cargo shortages at the first ports, is also eliminated.

4.Condensation

Introduction
Sweat is the term commonly used to describe condensation that forms in a vessel’s cargo spaces. This formation of moisture can cause damage to and/or deterioration of the cargo. The vessel has a very important role to play in avoiding this damage. Sweat can result from the vessel’s improper ventilation of the cargo space, or lack thereof, and damage can be minimised or even avoided by proper cargo stowage arrangements. Experience is that a claimant will invariably allege a failure of the vessel to follow proper ventilation practice or to properly stow the cargo. Under the Hague/Hague-Visby Rules this would be an alleged breach of Article III Rule 2.2. Unfortunately, in too many cases, the carrier is unable to sustain a defence to these allegations, not only because evidence suggests that the vessel has been at fault, but also because the vessel does not have sufficient evidence (e.g., proper ventilation records).

Types of sweat and how they form
The two main types are cargo sweat and ship’s sweat. In this respect it is important to understand what is meant by “dew point”. All air contains water vapour of varying quantities. The dew point indicates the amount of moisture in the air. The higher the dew point, the higher the moisture content of the air at a given temperature. Conversely, the dew point of humid air will be higher than the dew point of dry air. Dew point temperature is defined as the temperature to which the air would have to cool (at constant pressure and constant water vapour content) in order to reach saturation. A state of saturation exists when the air is holding the maximum amount of water vapour possible at the existing temperature and pressure. Condensation of water vapour begins when the temperature of air is lowered to its dew point and beyond.

Cargo sweat
Cargo sweat is condensation which forms on the cargo. It occurs when the temperature of the cargo is less than the dew point of the air in the hold. The cargo cools the air in contact with it and condensation forms on the cargo. The cargo may therefore be damaged by direct contact with moisture. Cargo sweat is most associated with the incorrect ventilation of warm moist air into a hold with cold cargo. It is akin to the condensation forming on a cold drinks can when taking it out of the fridge on a summer’s day.

Ship's sweat
Ship’s sweat is condensation which forms on the internal ship’s steelwork. It occurs when the temperature of the ship’s steelwork is lower than the dew point of the air in the hold. Condensation will form on the deckhead and/or on the inside of the shell plating. This moisture can then drop down from the deckhead on to the surface of the stow or come into contact with the cargo stowed directly against the sides of the hold. Ship’s sweat is most associated with a voyage to a colder climate and the failure to ventilate the hold, replacing moist air from the load port or air made moist by the cargo, with drier air. It is akin to the condensation forming on the window when taking a warm shower on a cold winter’s day.

Proper ventilation practice to avoid sweat
The decision to ventilate and, equally important, when not to ventilate, so as to avoid sweat, should largely be based on the following considerations:

The nature of the cargo and its packing – There are two basic groups of cargo, which pose significantly different risks of sweat: hygroscopic and non-hygroscopic.

Hygroscopic cargoes
Hygroscopic cargoes contain moisture, mostly in natural form; for instance, agricultural, fish and forest cargoes. For example rice has a moisture content of around 14%. It is important to note that these cargoes can absorb and release moisture. It is more likely that damage is caused when moisture is absorbed. A hygroscopic cargo with a moisture content and temperature such that water vapour will leave the cargo and enter the hold air will result in the build up of moist air and increase the risk of sweat.

Non-hygroscopic cargoes
Non-hygroscopic cargoes contain no moisture; for example, steel. Whilst non-hygroscopic cargoes may be wet before shipment, e.g., because they have been affected by rain before loading, it is better to avoid shipment of wet cargo rather than face the difficult task of deciding whether or not to ventilate. Non-hygroscopic cargoes do not give off moisture, but may absorb or be damaged by it.

Packing
Packing is an important factor and, for the purposes of ventilation, it can essentially make a non-hygroscopic cargo a hygroscopic cargo and vice-versa. For example, wood is hygroscopic and is often used as packing. Again however, the emphasis should be on avoiding shipment of wetted cargo.

Climatic changes on the voyage
Consideration needs to be given to the temperature and humidity conditions expected from the place of loading through the voyage to the place of discharge, as is relevant to the time of year. The term climate includes here the sea temperature, as that has particular relevance insofar as ship’s sweat is concerned. The sea temperature will have the greatest effect on the temperature of the steelwork in the hold which is adjacent to or in contact with the sea.

Putting together all of these factors, the risk of sweat can be predicted and therefore, broadly speaking, it can be decided whether ventilation is necessary, unnecessary or to be prevented.

Some examples
Hygroscopic cargo from warm to cold climate – There is a danger of heavy ship’s sweat and vigorous ventilation will therefore be necessary to replace moist air with drier air. The air in the hold may already be moist from ambient air at the place of loading, but is also likely to receive large volumes of moisture from the cargo itself. The aim is to lower the dew point temperature, thus making it unlikely that the steel structure of the vessel can cool air in contact with it sufficiently to reach that temperature.

Hygroscopic cargo from cold to warm climate – The risk of sweat is generally low and ventilation is therefore largely unnecessary. There is a risk of cargo sweat if warm moist air is introduced into the hold.

Non-hygroscopic cargo from warm to cold climate – There may be a risk of ship’s sweat if the hold air is moist from the load port. Ventilation to improve the dew point of the hold air is therefore advantageous.

Non-hygroscopic cargo from cold to warm climate – Cargo sweat is likely if warm moist air is introduced into the hold. Ventilation is not therefore necessary and the holds should be sealed.

As an aide mémoire, mariners have often relied on the following very general rule:
“Warm to cold: ventilate hold
Cold to hot: ventilate not”
It is important to remember, however, that the vessel will often pass through different climatic regions. In the example given for ship’s sweat above, whilst ventilation was necessary in the first part of the voyage, it was not necessary in the second part from the Cape of Good Hope to West Africa. It may also be very dangerous to ventilate, as has been shown in the example given above for cargo sweat. In that case the vessel ventilated whilst transiting humid conditions in the Red Sea, with the result that moister air was introduced into the holds. With all this in mind, a rule is required to ensure that, when the vessel does ventilate, it improves the air conditions in the hold, and thereby reduces the risk of sweat developing.

The Dew Point Rule
The Dew Point Rule is probably the most common rule followed to ensure best ventilation practice. It is simply:

• Do not ventilate if the dew point of the ambient air is higher than the dew point of the air inside the cargo space.
  
• Ventilate only if the dew point of the ambient air is lower than or equal to the dew point of air inside the cargo space.
  
• Remember, a higher dew point is bad and a lower dew point is good.
  
• Clearly, when it is raining, snowing, etc., or it is foggy, misty, etc., it will not be safe to ventilate.
  
  

The sea conditions
If, in adverse sea conditions, there is a risk of sea spray entering the ventilation openings to the cargo spaces, no ventilation should take place and the ventilator openings should be closed and sealed.

Inspections of the cargo spaces
The cargo spaces should be inspected regularly to check for signs of sweat (providing it is safe to enter).

Hours of darkness
Providing ventilation can and should be carried out, based on the above considerations, ventilation should continue to take place night and day. A failure to ventilate at night will probably be viewed unfavourably by a court or arbitration tribunal, unless of course there was a valid reason not to ventilate.

Shippers’ instructions
Shippers may have special instructions for ventilation. If these are at odds with what the vessel would expect, it would be prudent to obtain the views of an expert.

Expert advice
If there is any doubt about ventilation, expert advice ought to be sought.

Ventilation systems
Vessels are normally fitted with one of two systems: natural or mechanical.
Natural ventilation simply describes a system whereby ambient air is allowed to enter and leave the hold naturally, via trunking connecting the hold to and above deck level.
Mechanical ventilation describes a system whereby air movement is forced, usually by electrical fans that are fitted in the ventilation trunking. These can usually be operated so as to either draw air into or eject air out of the hold.

System features
In the hold there is usually two or more ventilation openings in the deckhead, one set forward, one set aft. This arrangement therefore only provides for surface ventilation of the cargo. It is less common for the trunking to extend down the bulkheads, so as to provide through ventilation (not normally required for bulk cargoes). Above deck the trunking may stand alone or may be built into part of a deck structure, e.g., the hatch coaming. Whatever the system, every ventilator should be provided with a means of closing, e.g., a screw-down mushroom cover, a flap or door. If the on-deck trunking is on a swivel arrangement, the vent opening can be turned to face forward when safe to ventilate (so as to maximise air intake), or aft when there is a risk of sea spray. The trunking arrangement may serve holds on an individual or common basis. Where cargoes with different ventilation requirements are stowed in different holds, care will need to be taken to arrange stowage and ventilators correctly.

Ventilation in practice
With natural ventilation, the air will usually move from forward to aft, with the movement of the vessel. Mechanical ventilation can aid this movement by setting fans to draw in forward and eject aft. It is important to avoid short-circuiting the air movement, e.g., via a hold opening between the ventilators. Fans can usually be operated at various speeds, so for example when vigorous ventilation is necessary high speeds can be used. If, despite ventilation, ship’s sweat is still occurring, the hatch covers can always be opened. Opening the hatch covers may also be necessary where there is an air pocket in the hatch square, caused for example by a high cargo stow.

System checks
Some points to check with ventilation systems:

• Closing appliances are often exposed on deck and easily become rusty. They need to be kept in good condition so that they can be opened and closed with ease. The ventilators will often need to be operated numerous times during the voyage, and often at short notice, e.g., sudden heavy sea spray. Surveyors for cargo interests often suggest that the vessel can not have ventilated properly when they find ventilators in poor condition and difficult to operate.
• The closing mechanism should always be checked to ensure an effective seal.
• Ventilators should be clearly marked to show when they are in the open or closed position (unless obvious), and also show which hold they serve.
• Fans for mechanical ventilation should be checked for operation before loading.
  
  

De-humidifiers
On some ships fixed or portable de-humidifying units may be fitted in the holds. These act to remove moisture from the hold air and therefore control the dew point.

Charterparty
The ventilation system should be properly described in the charterparty and care should be taken to avoid accepting ventilation requirements, which may be difficult or even impossible to comply with. It is also a good idea to obtain written acknowledgment from the shipper where the vessel is only fitted with natural ventilation, particularly on voyages where ship’s sweat is expected. The shippers are then on notice of the vessel’s ventilation limitations.

Temperature measurements and ventilation records
Determining the dew point
Compliance with the Dew Point Rule requires determination of the dew point. If cargoes requiring ventilation are to be carried it is very important that the vessel has on board the necessary instruments, with spares, to determine the dew points, and that the crew is properly trained to use the instruments. If the vessel is not properly equipped it risks being uncargoworthy and in breach of Article III Rule 1 (b) of the Hague/Hague-Visby Rules. Most vessels have a basic psychrometer on each bridge wing housed within a Stephenson screen. The psychrometer consists of two thermometers which are identical, save for one which has its bulb covered with a jacket of tight muslin cloth, and which must be saturated with distilled water. The dew point is determined from careful reading of the temperature on the two thermometers and by reference to dedicated dew point tables, such as those found in the Mariner’s Handbook. Using the psychrometer on the windward bridge wing will give the dew point of the ambient air. For the holds, a psychrometer can also be used, preferably within the hold (providing it is safe to enter). Temperatures should be taken at various places and sufficient time needs to be allowed for thermometers to acclimatise (the psychrometer should be waved in the air). If the holds can not be entered, the psychrometer may be placed down the outlet ventilation trunk or hold access.

Records
As mentioned in the introduction, records are essential to the carrier’s defence of cargo claims. It may be that, on some voyages, sweat can not be prevented. For example, ship’s sweat resulting from ventilation being restricted due to say fog or heavy seas on deck. In those circumstances it may be necessary to evidence that the vessel did ventilate as much as it reasonably could, when it could. On the other hand, moisture damage to the cargo may be due to the inherent nature of the cargo itself, e.g., pre-shipment moisture content, and the carrier may need to evidence that when the cargo was ventilated it was ventilated correctly. It is important to bear in mind that, even if poor ventilation practice has only contributed to cargo damage, with the predominant cause being, for example, inherent vice of the cargo, the carrier faces the difficult, if not impossible, task of having to prove the extent of damage caused by the vessel’s wrong doing so as to avoid liability in full.

It is strongly recommended that a separate ventilation log be drawn up where the observations for each hold are recorded. A suggested proforma is set out below.

In addition to the ventilation record, it is also important to take and record the bilge soundings, as these too will be evidence of moisture within the hold. Obviously, the bilges should be dry before loading.