Section 143.500 - Applicability(a) This subpart applies to a new towing vessel, as defined in § 136.110 of this subchapter, unless it is an excepted vessel.(b) Machinery or electrical systems of a novel design, unusual form, or special material must meet section § 143.210 .(c) Unless otherwise noted in §§ 143.515 and 143.520 , new towing vessels must also meet the requirements of subpart B of this part.