Question

a) State the purpose of cofferdams

b) State where cofferdams are most likely to be found in each of the following;

i) Dry cargo vessels

ii) Oil tankers

c) Identify, with reasons, the general precautions which must be observed before and during entry to cofferdams and state official guidance on entry into void spaces is given;

Answer.

a) The purpose of cofferdams are to prevent leakage of one tank or double bottom to another i.e., there would be a cofferdam between fuel tanks and fresh water tanks. They also allow for inspection of tanks, cofferdams should also be sounded regularly to check for leaks.

b)

i) On dry cargo vessels, cofferdams would be found between fuel tanks and cargo , ballast tanks and cargo, also found around the main engine LO drain tank.

ii) On oil tankers, cofferdams would be found between the oil cargo tanks and the accommodation or engine room, in some cases this can be the pump room, also there will be a cofferdam around the main engine LO drain tank.

c) Precautions taken before entry into an enclosed space are as follows; An entry permit must be obtained from a responsible officer, you may be the issuing officer. The space is to be well ventilated and oxygen levels tested by an 02 meter. Safety gear, such as self contained breathing apparatus sets must be at hand, rescue lines, communications. Also while anyone is in the enclosed space, someone must be on standby at the entrance who must be in communication with the people in the space and also must be able to raise the alarm if they are to get into difficulties.

Official guidance on entry into enclosed spaces can be found in "M" notices and also in the "Code of Safe working practices"