Moisture and sweating. It sometimes comes from the moisture given off by various types of cargoes. It condenses on the cold steel surfaces of the hold, especially when the ship runs in cold weather. It can be also caused by hot and damp air coming into contact with the cold surfaces of the hold. Due to sweating and moisture textile goods get discoloured, metal get rusted, timber get stained, chemicals and minerals dissolved, cement and flour get caked, fibrous goods can shrank in the volume, grain may sprout and beans may get rotten. Al this can be prevented or at least reduced by proper ventilation, good dunnaging and matting.
Mixing. It often occurs when different lot and parcels of cargo, both bulk and general, penetrate their separations. Nowadays the purity of many products requires the perfect stowing and great care must be taken to prevent mixing. All marks and numbers have to carefully checked before shipment and during loading and discharging operations. Mixing of coffee beans, cocoa beans and bales of wool occurs very often due to the negligence of the shippers and the Chief officers at the port of loading where the different kind of cargoes for the different consignees are sometimes loaded with mixed marks and numbers.
Rain damage. It usually caused by loading in rain weather or in fog conditions, during sleet or drizzle and later due to the lack of good ventilation. Most damage can be avoided by stopping loading before it has begun to rain, and covering lots of cargo or closing the hatches just in time. Proper ventilation may reduce the effects of rain damage.
Heat, fire and explosions. Many commodities are liable to spontaneous combustion and some goods may be easily ignited by cigarette butts or ends. Ends of cigarettes can be buried deep in the sawdust and can burn for days afterwards so the vessel can be far off the sea before the fire is detected. Cotton -if is wet will heat and deteriorate, but if is in contact with oil or grease , it is liable to spontaneous combustion. Rise, oats, many types of oil seeds, pallets and cakes when ripe, may give a sweat. Eventually the seeds may start germinating. Heating of such cargoes may particularly occur when they are loaded in bulk in large quantities in to the lover holds. All types of coal are liable to spontaneous combustion, especially when carried in large quantities and over a longer period of time. The temperature in the holds should be measured during each watch and special precautions should be undertaken when the temperature exceeds 40 C. Good surface ventilation is absolutely necessary to prevent the fire and the damage caused by it.
Dangerous goods and explosives have to be stowed according to special regulations, far away from the engine room and the boiler room. That may be stowed on deck, either in very well ventilated places.
Most damage can be avoided by proper stowage conforming to safe regulations and rules of the IMDG code.
Damage due to inherent vice is rather difficult to prevent as the latent defect is a natural quality of the goods and very often may not be discovered.
Fruits is one of the commodities most liable to be damaged by its own inherent nature.This kind of damage can be prevented by a very carefuor examination of cargo before shipment , by proper stowage and ventilation. The temperature and the humidity in the holds have to be measured during each watch . The ideal situation will be to carry fruits and other special cargoes in air-conditioned holds.
Damage caused by rats and mice and various kinds of bugs has been decreasing steadily, mainly due to the cleanliness maintained aboard ships. However, special precautions must be taken such as rat guards on mooring ropes, periodical fumigation of holds, store rooms, frequent disinfections , deratisation.