Question

(a) Describe how water tightness is maintained where bulkheads are pierced by longitudinal beams or pipes. (6)

(b) A triangular bulkhead is 7 m wide at the top and has a vertical depth of 8 m. Calculate the load on the bulkhead and the position of centre of pressure if the bulkhead is flooded with sea water on only side: (10)

(i) To the top edge

(ii) With 4 m head to the top edge.

Answer 1

Part (a)

Water tightness of

bulkheads that are pierced by longitudinal beams or pipes:

Bulkheads must be made structurally watertight without the use of wood packing.
Pipes passing through bulkheads are either welded or fastened to the bulkhead using studs or hoses secured through tapped holes in the plating.
When a bulkhead is pierced by a longitudinal beam, the openings are kept as small as possible, and doubler plates are welded on each side to maintain watertight integrity.
Sealing materials and gaskets are used, particularly for pipes, cables, and similar penetrations.

Part (b)

$$\left(a\right)\:Load\:on\:bulkhead=\rho gAH$$

$$=1025\times9.81\times\frac{7\times8}{2}\times\frac83$$

$$=750.8\times10^3N$$

$$=750.8KN$$

$$Centre\:of\:pressure\:fron\:top=\frac12D=\frac12\times8$$

$$=4m$$

$$\left(b\right)\:Load\:on\:bulkhead=1025\times9.81\times\frac{7\times8}{2}\times\left(\frac83+4\right)\times$$

$$=1.877\times10^6N$$

$$=1.877MN$$

$$For\:triangle\:I_{NA}=\frac{1}{36}BD^3$$

$$Centre\:of\:pressure\:from\:surface\:of\:water\:=\frac{I_{NA}}{AH}+H$$

$$=\frac{\frac{1}{36}\times7\times8^3}{\frac12\times7\times8\times\left(\frac83+4\right)}+\left(\frac83+4\right)$$

$$=\frac{2\times7\times8^3}{36\times7\times8\times6.667}+6.667$$

$$=7.20\:m$$

$$Centre\:of\:pressure\:from\:top\:of\:bulkhead$$

$$=7.20-4$$

$$3.2m$$

✓ Verified Model Answer (Text Solution)

Water tightness of