Arrangements to resist pounding

The fore end structure is strengthened to resist pounding form the collision bulkhead to 25% of ships length forward.

The bottom shell plating adjacent to the keel is thicker by about 15% to 30% depending on the length; larger the length less the thickness.

In transversely framed bottom shell longitudinal grider may fitted extending up to top at a space of 2.2m and intermediate half-height girders are fitted after every girder reducing the unsupported span to 1.1m. Solid floors are fitted at every frame space.

In longitudinally framed bottom shell the spacing between the frames in 700mm. Solid floors are fitted at every alternate side frames. Full height side girders are fitted every 2.1m.

Side Shells

1. The side shell also forms the watertight skin of the ship. The shell plating also contributes to the longitudinal strength of the ships structure. It also acts as pillar to load on decks.

2. The thickness of the shell plating depends largely on the length of the ship and the frame spacing.

3. Shells are ticker at the bottom and also towards the ends where the bending moments are low.

4. The strake of the side plating nearest to the deck is known as the sheerstrake. The sheerstrake is increased in the thickness (10 to 20% more than other plates) or a high ensile steel is used. This is because this section is furthest form the neutral axis.

5. The region where the sheerstrake meets the deck plating is known as the Gunwale.

6. All openings on the side shells will have rounded opening to avoid stress concentration.7. The framing could be transverse or longitudnal. Transverse framing of side shell consists of vertical stiffeners. These are attached to the deck and bottom structure by means of brackets. Frame spacing is not normally more than 1.0m but are always reduced in way of pounding region and aft and fore peak regions.Longitudinal framing is used on the side shells in conjunction with the deep-flanged web frames. The transverse webs are spaced at a distance of no more than 4.0m apart are fitted for supporting the side longitudinals. The web frames is the machinery space are drop to withstand vibration forces.

8. Bilge keel is provided at right angle to the radiused bilge plate. These are provided where flat as keel cannot provide any stability against rolling. They do not extend beyond the extreme breadth line. It is fastened with the hull is such a way that it cannot damage the hull.

Arrangements to resist Panting

15% of the length of the ship form the stem is strengthened to resist effects of panting. Strengthening is also carried out at the aft of the aftpeak bulkhead.

Side stringers are provided 2m below the lowest deck and the side stringers meet at the fore end.

Stringers are extended to the collision bulkhead. This forms a ring (or a triangle) around the tank and this also supports the bulbhead stiffeners.

Channel beams are fitted in line with the stringers at alternate frames and connected to the frames by brackets.

Every other frame is bracketed to the stringer.

The free edge of the bulkhead stringer may strengthen beams.

The tank top is not carried into the forepeak but solid floors are provided for bottom strengthening. The solid floor top edge is flanged and re slightly thicker than the DB floors.

Side shell frames are smaller than the normal hold frames. Angle pillars support alternate frames at the top and deck beams on both sides. At the bottom the frames are connected to the floors.

A partial wash plate is fitted to reduce the movement of water.

Between collision bulkhead and 15% of ships length form forward the frame strength is increased by 20% and the frame spacing between collision bulkhead to 20% of ships length form forward the frame spacing is reduced (to about 700mm; normally this is 760 or 900mm). light side stringer may also be fitted in line with the main stringers but may be dispensed with by increasing the shell thickness. The collision bulkheads are stiffened by vertical bulb angles.

The thickness of the radiused plate is more than the side shell and it reduces towards the top.