How is cargo ship structured

Ballast tanks are designed for ballast. Ballast is the extra weight, most often in the form of port water, which helps a ship to:

  • Improve ship stability. When the ship is empty or when the cargo is unfavorably loaded (e.g. timber, containers), the ballast tank helps maintain favorable stability.
  • Balance the ship’s longitudinal and transverse tilts. The weight on the ship is not evenly distributed, so we need extra weights on the opposite sides to keep the ship in balance. We do this by filling the tanks with ballast on the opposite side. This is especially important in the port when handling cargo.
  • Empty ship load. Many times the ships, when they unload all their cargo in one port, head to the next port completely empty. An empty ship is less sunken and the surface of its freeboard becomes larger. This makes the ships more exposed to the waves and wind, making it harder for them to maneuver in the right direction and significantly reduces their speed.
  • Proper sinking of the ship’s screw. The ship’s screw has the highest efficiency when fully submerged and when the ship is slightly inclined towards the stern. As this is difficult to achieve only with cargo and other weights on board, we need to use ballast. Which tanks are specified for ballast depends on the type of a ship.
Cargo ship

Likewise, not all ships have all the tanks listed. Ballast tanks are usually double bottom, fore peak, after peak, wing or top tanks. On some ships holds can also be used for ballast (bulk carriers, tankers). New tankers are no longer allowed to load ballast into holds, but must have a segregated ballast tank (SBT) system. Some ships (e.g. ships carrying 11 cars) already have permanent ballast installed in certain ballast tanks. This is already included in the total mass of the empty ship.

Fuel oil tanks are designed to store heavy oil (fuel oil), light oil (diesel oil, marine diesel), and lubricants. The fuel is usually stored in double bottom tanks. However, before the fuel enters the engine, it is first pumped into a sludge tank, where it is allowed to settle for a while. It is then purified through a separator and placed in a daily tank from where the fuel enters the engine. Fresh water tanks store drinking water and feedwater (boiler water).

Drinking water is intended for drinking and use in the ship’s kitchen. We use (boiler) feedwater for washing, laundry, cleaning, toilet water, boiler water, etc. Drinking water tanks must be specially adapted for this purpose, water level gauges must be outside of the tank and must be capable of disinfecting water. Bahamaritime company from west Africa can provide your ship with fresh water in Conakry ans Kamsar ports.

Waste fluid tanks are usually as follows: fecal water tanks, waste oil tanks, and cargo residue tanks. The regulations for these tanks are written by the MARPOL Convention. Dirty water tanks are designed to collect waste water from kitchens, toilets, bathrooms and other similar spaces. From there, they can then be discharged through the treatment plant into the sea.

Waste oils are collected in sludge tanks. Waste oil is collected at the bottom of the engine room, and then purified with a separator, then finally the purified water is pumped into the sea and waste oils are stored in a special tank. The contents of the tank must be emptied on shore or incinerated. Tankers must have special slop tanks with a volume of at least 3% of the cargo capacity. We store leftovers of cargo after washing them inside these tanks. If there is water present, it can be purified by separators and pumped into the sea, and the residual cargo must be appropriately discharged. 

Bilges are wastewater collectors in holds and engine rooms. Apart from this function, we can also determine the state of the water in the space by measuring the bilge regularly, and thus see if there has been a water leak.

The bilge has its own pipeline through which we pump waste water. Hold water, if clean, can be pumped into the sea, while the oily bilge water in the engine room must first be separated in accordance with the rules of the MARPOL convention so as to prevent contamination. Ships also have several pipelines. Each pipeline also has one or more pumps that are used by that pipeline. Bow pipelines are usually installed on deck, some ships have a special duct keel, and some have pipelines running through thin double bottoms. The most important pipelines are: cargo, bilge, ballast and fire protection pipelines. 

Ships carrying liquid cargo have cargo pipelines. The number of those depends on the variety of cargo carried by the ship. Ships carrying chemicals have the most cargo pipelines. The bilge pipeline is extremely important because it can draw water from holds in the event of water flooding the space and thus save the ship from sinking. In normal circumstances, it is used to pump water from the bilge. Ballast pipelines should be very high performance especially if loading / unloading capacities are very high. 12 The fire pipeline is installed throughout the ship and must meet the requirements of the SOLAS Convention. The spare fire pump must be located outside the engine room.