You are the credentialed operator of a 100 GT towing vessel sailing coastwise. What percentage of the deck crew must be able to understand the language commonly used onboard the vessel?

Correct Answer: Option D — 75%

46 CFR 15.730 requires that at least 75% of the deck crew on a vessel must be able to understand any order spoken by the officers. This ensures that critical safety commands, especially during emergencies, are understood by the majority of the crew to prevent accidents and ensure effective coordination.