What provision is made for sea chests for removal of air ingested into the sea chest of a machinery space sea water cooling system?

Correct Answer: Option D — The air may be continuously removed by an open valve located in the vent line originating from the top of the sea chest and terminating above the deep-draft load line.

Sea chests must be vented to prevent air accumulation, which can cause pump cavitation and loss of suction. Regulations require these vent lines to terminate above the vessel's deepest load line to ensure that air is effectively displaced and to prevent seawater from flooding the machinery space through the vent piping.