Question 1979 Deck Safety

The correct answer is D) steel plates. According to US Coast Guard regulations, tonnage openings on vessels must be closed by means of steel plates. Steel plates provide a sturdy, durable, and watertight seal to maintain the vessel's structural integrity and prevent the ingress of water, which is crucial for maritime safety. The other options, such as press board, wooden hatch boards, or even steel hatch boards, would not meet the regulatory requirements for properly sealing tonnage openings on a vessel.