Before containerisation, apart from bulk, most cargoes were handled as general cargoes. Even vehicles were handled as general cargo before the advent of vehicle carriers and ro-ro vessels. Most ships had their own handling facilities in the form of derricks. Now the majority of cargo is shipped in containers, negating the need for ships to have their own cargo handling gear, relying entirely on shore facilities. Much of the general cargo carried now is of a type that cannot be readily packed into containers. General cargo is loaded from the dock by traditional dockside cranes except where the weight precludes this. To speed up loading, much of the cargo is unitised. The process of unitising consists of strapping together individual items of cargo to form a single unit. Ships designed to carry heavy cargoes usually have their own cargo handling gear in the form of heavy duty derricks or cranes.
Many ships now have cranes instead of derricks. With the boom in the boating leisure market, some companies now specialise in the transportation of luxury pleasure craft. The craft are either lifted off the dock or can be directly lifted from the water. The boats are lifted using a spreader frame with cargo straps.
Deck cargoes of luxury pleasure boats and cars.
Loading equipment onto the Antarctic survey vessel Sir James Clark Ross.
Most cargo vessels used to have tween decks (in between decks) in the holds. Not many cargo ships are fitted with these now. This picture clearly shows the tween decks in position and filled with cargo. Also shown is the holds of a vessels with the tween decks removed and stacked. Cars are now mostly carried by special vessels, but for small quantities and shipments to ports where there are limited unloading facilities, a few vessels still carry cars like this, and as deck cargo.
Deck cargo of wind turbine blades. |
Cotton Bales. |
Vessels are often loaded with timber as the picture shows. Vertical timber side members are used to secure the cargo either side. The cargo is often piled high because timber is a relatively light cargo.
REEFER CARGOES
To facilitate loading, many vessels are fitted with side loading doors and a pallet lift. |
Palletised cargo being manually stacked in the hold. |
Loading fruit packed in boxes with a conveyor belt system. |
Squid frozen into blocks. |
Apples, pears, kiwis, grapes and stonefruit (peaches, cherries etc.) are traditionally the main products that dominate this segment of reefer transportation. As many of us know from our own gardens, deciduous fruits are highly seasonal. This makes the deciduous trade very different from the banana trade, which is a 12-month business. Optimum transit temperatures for deciduous fruit vary greatly per type and variety, but mostly range between –1 and +4°C. The ability of the fruit to resist pressure is indicative of its ripeness and can be measured with a penetrometer.
The appropriate carriage temperature for bananas is limited by the susceptibility to chilling injury. Generally a carriage temperature of +13,3°C is to be maintained during the sea voyage. Bananas should arrive in a fresh, green unripe condition. If premature ripening takes place during the voyage, progressive ripening by emission of high amounts of ethylene can hardly be avoided. Pictured here are bananas discharged from a vessel in overripe, partially fermented condition due to a failure of the vessel's refrigeration system during the voyage.
In comparison with the previously mentioned groups of cargo, citrus fruit (oranges, tangerines, lemons, limes, grapefruit and mandarins) are a relatively simple cargo to carry. A minor fluctuation in the hold temperature will not have disastrous effects. Successful shipments have even been carried out using ventilation alone, without refrigeration. Amongst the most familiar fungi affecting citrus fruit are green and blue penicillium mould growth (shown to the right) which is accelerated by high storage temperatures. Alternatively, citrus fruit is also sensitive to low temperatures injuries, which take the form of brown marking/pitting on the rind.
