Q2: With reference to cargo hatch covers on large container ships: (a) Describe how they are tested for water tightness (... | SC&S MEO Class II

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Q2 (10 Marks) Hull Construction

SC&S • Written Exam

With reference to cargo hatch covers on large container ships:

(a) Describe how they are tested for water tightness

(b) Explain how the weight of the hatch and containers is transferred to the ship's structure whilst allowing for deflections of the hull in a seaway

(c) Describe, with the aid of a sketch, the type and location of damage that can occur due to wear of the hatch supporting arrangements.

Appeared In: Aug 2022

✓ Verified Model Answer (Text Solution)

Structured for DG Shipping MEO Class II examination scoring criteria.

Exam Ready

Part (a)

Cargo hatch cover can be tested for water tightness by Hose test. In this test, a water spray from a nozzle of 12mm diameter is sprayed over the joint of hold and cover from a distance of 1m to 1.5 m with a pressure of 0.5 m/sec water jet. Any leak of water inside the cargo hold will indicate a gap between the hold and the cover.

Other methods include:

Chalk test - on top of bar that the hatch sealing rubber rests
Ultrasonic testers are available to check the seals
Inspect from inside of the closed hatch for any light penetrating

Part (b)

Weight-bearing pads are fitted on large hatch covers to relieve the load on the seals. Weight-bearing pads allow the hatch to flex as well. These pads allow the hatch to move, without compromising the watertight seal or structural integrity. This flexibility ensures that the loads are still transferred without stressing the hatch covers or the deck structure excessively

Part (c)

Wear of the support arrangements can put excessive loading on the seal, which will cause the failure of the sealing arrangement. The hatch coaming can be overloaded and could cause cracking in side plates and buckling of support stays

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