Some Deffination about Ship's dimention

Length between perpendiculars (L.B.P.)

The fore perpendicular is the point at which the Summer Load Waterline crosses the stem. The after perpendicular is the after side of the rudder post or the centre of the rudder stock if there is no rudder post. The distance between these two points is known as the length between perpendiculars, and is used for ship calculations.

Freeboard

The distance from the waterline to the top of the deck plating at the side of the deck amidships.

Camber or round of beam

The transverse curvature of the deck from the centreline down to the sides. This camber is used on exposed decks to drive water to the sides of the ship. Other decks are often cambered. Most modern ships have decks which are flat transversely over the width of the hatch or centre tanks and slope down towards the side of the ship.

Depth moulded (D. Mid)

The depth measured from the top of the keel.

Sheer

The curvature of the deck in a fore and aft direction, rising from midships to a maximum at the ends. The sheer forward is usually twice that aft. Sheer on exposed decks makes a ship more seaworthy by raising the deck at the fore and after ends further from the water and by reducing the volume of water coming on the deck.

Rise of floor

The bottom shell of a ship is sometimes sloped up from the keetto the bilge to facilitate drainage. This rise of floor is small, 150 being usual.

Bilge radius

The radius of the arc connecting the side of the ship to the bottom at the midship portion of the ship.

Tumble home

In some ships the midship side shell in the region of the upper deck is curved slightly towards the centreline, thus reducing the width of the upper deck and decks above. Such tumble home improves the appearance of the ship.

Flare

It is the tendency of the section to fall out of the middle line plane from the vertical as it approaches the deck edges. This is the opposite tendency of the “Tumble Home”.

Displacement

The mass of the ship and everything it contains. A ship has different values of displacement at different draughts.

Lightweight

The mass of the empty ship, without stores, fuel, water, crew or their effects.

Deadweight

The mass of cargo, fuel, water, stores, etc., a ship carries. The deadweight is the difference between the displacement and the lightweight

i.e., displacement = lightweight + deadweight

Shell Plating

The keel plate is about 30% thicker than the remainder of the bottom shell plating, since it is subject to wear when docking. The strake adjacent to the keel on each side of the ship is known as the garboard strake which is the same thickness as the remainder of the bottom shell plating. The uppermost line of plating in the side shell is known as the sheer strake which is 10% to 20% thicker than the remaining side shell plating.

Coffin plate:

A fabricated sternframe used to support an unbalanced rudder. The sole piece is a forging which is carried aft to form the lower gudgeon supporting the bearing pintle, and forward to scarph to the aftermost keel plate which is known as a coffin plate because of its shape.

Beam knee

The top of the hold frames terminate below the lowest deck and are connected to the deck by beam knees (Fig. 4.10) which may be flanged on their free edge.