Question

With reference to collision bulkhead explain the following using sketches as required:

(a) Purposes of collision bulkhead.

(b) Construction of collision bulkhead.

(c) Regulations governing the position and construction of such a bulkhead.

Answer 1

Part (a)

It is the foremost transverse watertight bulkhead, fitted near the bow.
Its primary purpose is to limit the flooding caused by a head-on collision or grounding damage to the forepeak, preventing water from flooding the main cargo or machinery spaces and thereby keeping the ship afloat.
It provides a watertight boundary so that damage to the bow does not compromise the rest of the hull.
It also acts as a structural stiffener for the bow region, resisting panting and pounding forces.
It protects the ship's buoyancy and stability in the event of forward damage.

Part (b)

It is a transverse watertight bulkhead of steel plating, stiffened by vertical stiffeners (usually angles or bulb plates) spaced about 600-750 mm apart.
The plating is generally thicker than other bulkheads because of the higher pressure head and the risk of damage.
Stiffeners are fitted on the after side (the dry side) so that the forward face is smooth, allowing water to run down and reducing the risk of damage to the stiffeners.
The bulkhead is connected to the shell plating, deck and bottom by efficient watertight connections, often with a larger radius at the bilge.
It extends from the keel (bottom shell) up to the freeboard deck, and in some designs to the superstructure deck.
No doors, manholes or openings are permitted below the freeboard deck in the collision bulkhead, except for a single pipe passing through with a valve operable from above the freeboard deck.
The stiffeners are connected to the deck and bottom by brackets or gussets to transmit the loads.

Part (c)

The collision bulkhead must be fitted at a distance from the forward perpendicular of not less than 5% and not more than 8% of the length of the ship (L), measured from the forward perpendicular. (For ships with a bulbous bow, the position is measured from the forward end of the length.)
It must be watertight up to the freeboard deck.
It must be fitted in all ships, and must extend to the freeboard deck.
No doors, manholes, ventilation ducts or other openings are permitted in the collision bulkhead below the freeboard deck.
A single pipe may pass through the collision bulkhead below the freeboard deck, provided it is fitted with a valve operable from above the freeboard deck, and the valve chest is secured to the bulkhead at the inboard end.
The bulkhead must be of adequate strength to withstand the pressure of water in the flooded forepeak, and is subject to classification society rules for plating thickness and stiffener spacing.
These requirements are set out in the International Convention on Load Lines and the SOLAS Convention, and are implemented through classification society rules.

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