A ship is a massive storage floating structure which is fundamentally used to store and transfer liquid or dry type of cargo from one port to another. A ship needs tonnes of oil- both fuel and lubricating, along with water so that its propulsion and other auxiliary systems can operate efficiently.
In order to store different types of oils and water, the ship is designed and constructed with several tanks. These tanks help to store fuel oil, lube oil, hydraulic oil, drinking water, fresh water, ballast water etc.
The size, number, type, and position of the tanks depend on the following factors:
- Size and type of the ship
- Propulsion plant, auxiliary engines type and design of other machineries.
- Area of voyage
Tanks are spread all over the ship from forward to aft and port to starboard. Different types of tanks present on the ship are:
- Fuel & Diesel Oil Tanks:
- Bunker tanks
These are the biggest tanks in terms of capacity present on board a ship. They are used to store fuel and diesel oil received in bulk after bunkering. The placement of bunker tanks are usually outside the engine room and they are generally a wing or double bottom tank. Low sulphur oil and marine gas oil is bunkered in separate dedicated bunker tanks to avoid mix up of fuel.
In general, more than two settling tanks are present and situated on a ship as part of the bulkhead of the engine room. Oil from the bunker tank is transferred into the settling tank. The diesel oil settling tank can be located as double bottom tank in the engine room. Settling tank for low sulphur oil and marine gas oil is kept separate from other fuel oil.
Service tanks onboard ships are used to store and supply treated oil to main engine, auxiliary engine and boilers. The number of such tanks can be one or more. Fuel oil and diesel oil service tanks are normally located as a part of the bulkhead of the engine room. Low service fuel oil (L.S.F.O) and marine gas oil (M.G.O) tanks are dedicated tanks to avoid mix up.
Over flow tank
Over flow tank is provided for both fuel and diesel oil system in the engine room for collecting the overflowed oil from bunker tank. Return lines and leak off lines may also be connected to overflow tank. It is a normal practice to have a common overflow tank for high and low sulphur system.
Emergency generator diesel oil tank:
Fuel for emergency generator is supplied form a separate diesel oil tank with capacity derived by the regulation given in SOLAS. The location of the tank is in the emergency generator room which is outside the engine room.
Lubricating oil tanks
It is almost impossible to think of any machinery operating without the use of lubricating oils. For this reason, various grades of lube oils are stored onboard ship. Different lube oil tanks present on board ship are:
Main Engine Crank Case (M.E.C.C) Oil Tank
The Main engine crank case oil is stored in one or more tanks and low sulphur system oil is kept in separate tanks. There are no other settling or service tanks in lube oil system and oil is taken directly from the main tank.
Main Engine Cylinder Oil Tank
The main engine cylinder oil is used inside the combustion chamber between the piston and the liner, and is stored in the cylinder oil tank. The bulk oil is bunkered directly into these tanks. The low sulphur oil is kept separate in different tanks.
Main Engine Cylinder Oil Daily Tank
The daily tank is located in the engine room and the oil is transferred from the storage tank to this daily tank. The capacity of daily tank is kept as per the main engine cylinder oil daily consumption.
Main Engine Turbocharger Oil tank
If the main engine comprises of a turbocharger system with forced lubrication, a turbocharger lube oil storage tank is provided.
Maine Engine Turbocharger Daily Lube Oil Tank
A daily oil tank is provided in the engine room. Oil as per the daily consumption of the turbo charging system is transferred from the storage tank.
Auxiliary Engine Lube Oil Tank
Auxiliary engine are 4 stroke engines and no separate cylinder lube oil is used. Therefore, only auxiliary engine main lube oil is bunkered and kept in storage tank. One or more tanks may be present as per the ships requirement.