Water-tight sliding steel doors positioned below the vessel's waterline must be capable of closing completely within how many seconds when the ship is upright?

Answer & Explanation

The correct answer is Option B: 45 seconds or less.

SOLAS regulations require that watertight doors below the waterline be capable of closing in a controlled manner within a specific timeframe (usually 20 to 40 seconds) to ensure that the vessel's subdivision remains effective in the event of flooding.