Aux 2 Unit 15 Bulkheads Q2 Answer

9.(a) State the purpose of the collision bulkhead and the regulations appertaining to its dimensions and position.(4)
(b) Explain the difference between A, B and C class bulkheads.(6)

(a) Purpose of the collision bulkhead and regulations appertaining to its dimensions and position (4 marks)

Purpose:

  • The collision bulkhead is the foremost watertight bulkhead fitted in a vessel to limit flooding in the event of damage to the bow caused by collision.
  • It ensures that, if the forepeak is breached, the remainder of the vessel remains buoyant and stable, preventing sinking.

Regulations (position and dimensions):

  • The collision bulkhead must be watertight, extending up to the freeboard deck.
  • According to international regulations (SOLAS / Load Line Convention):
    1. The bulkhead must be located not less than 5% of the vessel’s length (L) aft of the forward perpendicular.
    2. It must be located not more than 8% of L (or 10 m, whichever is less) aft of the forward perpendicular.
  • No doors, manholes, or access openings are permitted below the freeboard deck.
  • Small openings above the load line (for access or ventilation) must have weathertight closures.

(Purpose 2 marks, regulations 2 marks = 4 total)

(b) Difference between A, B and C class bulkheads (6 marks)

These classifications are defined by SOLAS and the Fire Safety Regulations to control the spread of fire and smoke on board ships.

A-Class Bulkheads (Fire-Resisting & Watertight)

  1. Constructed of steel or equivalent material, watertight and gas-tight.
  2. Capable of preventing the passage of smoke and flame for at least 1 hour.
  3. Insulated so that the average temperature rise on the unexposed side does not exceed 140°C, and no point exceeds 180°C within the specified time (usually A-60, A-30, etc.).
  4. Typical use: Between machinery spaces, accommodation, galleys, and cargo holds.

B-Class Bulkheads (Smoke-Tight & Fire-Retarding)

  1. Constructed of non-combustible materials, but lighter than A-class.
  2. Prevent the passage of flame for at least 30 minutes.
  3. Insulated to limit temperature rise on the unexposed side to 225°C maximum.
  4. Typical use: Within accommodation spaces and between cabins and corridors.

C-Class Bulkheads (Non-Combustible)

  1. Constructed of non-combustible materials, but not required to be insulated for temperature control.
  2. Provide no specific fire-resistance period, only required to be flame-retardant.
  3. Typical use: Partitions within accommodation areas or non-critical spaces where fire spread risk is low.