Air-cooled radiators for gasoline propulsion engine cooling __________. (small passenger vessel regulations)

Correct Answer: Option D — are permitted on vessels less than 65 feet carrying not more than 12 passengers

46 CFR Subchapter T permits air-cooled radiators for propulsion engines only on smaller vessels, specifically those under 65 feet in length carrying 12 or fewer passengers. This exception recognizes the lower risk profile of these smaller craft while still requiring adherence to strict marine installation safety standards.