Main thrust block is placed close to the propulsion machinery in order to reduce any problem due to:. – Additional longitudinal girders are fitted in way of heavy auxiliary machinery such as generator. – In motor ships, where a drain tank is required under the machinery, a cofferdam is fitted giving access to the holding down bolts and isolating the drain tank from the remainder of the double bottom tanks.

– Boiler bearers are similarly fabricated with support from transverse bracket and longitudinal members. – Often the machinery is built up on seating forming longitudinal bearers which are supported transverse by tripping brackets in line with the double bottom floors, the longitudinal bearers being in line with the double bottom side girders. – In the machinery spaces, forces of pulsating nature are transmitted through the structure due to the general out of balance forces of machinery parts, so additional transverse flows and longitudinal intercostal side girder are provided to support the machinery effectively and to ensure rigidity of the structure.

– The main engine seating are in general integral with this double bottom structure, and the inner bottom in way of the engine foundation has a substantially increased thickness of about 40mm and is continuous to the thrust block seating. Bracket floor, Open floor,Skeleton floorĭOUBLE BOTTOM ARRANGEMENT IN MACHINERY SPACE Note: Fuel storage is not allowed since 2007 on DB tanks as regulated by MARPOL.Ģ. – The space in between the two bottoms which is called as a double bottom space and is often used as storage tanks for storing fuel, ballast water, Technical Water (Non-potable). ARRANGEMENT OF DOUBLE BOTTOM & FRAMING IN MACHINERY SPACE – ARRANGEMENT OF DOUBLE BOTTOM & FRAMING IN MACHINERY SPACE – A double bottom in a ship is a ship hull construction method where the bottom of the ship has two distinct layers of watertight hull floor where one of the outer layer forming the normal hull of the ship, and the inner layer forms a superfluous barrier to seawater in case the outer hull is breached.

Margin plate ship construction