Section 27.211 - What are the specifications for fuel systems on towing vessels whose construction was contracted for on or after January 18, 2000?(a) You must ensure that, except for the components of an outboard engine or of a portable bilge pump or fire pump, each fuel system installed on board the vessel complies with this section.(b)Portable fuel systems. The vessel must not incorporate or carry portable fuel systems, including portable tanks and related fuel lines and accessories, except when used for outboard engines or when permanently attached to portable equipment such as portable bilge pumps or fire pumps. The design, construction, and stowage of portable tanks and related fuel lines and accessories must comply with ABYC H-25 (incorporated by reference in § 27.102 ).(c)Fuel restrictions. Neither you nor the master or person in charge may use fuel other than bunker C or diesel, except for outboard engines, or where otherwise accepted by the Commandant (CG-ENG). An installation that uses bunker C, heavy fuel oil (HFO), or any fuel that requires pre-heating, must comply with subchapter F of this chapter.(d)Vent pipes for integral fuel tanks. Each integral fuel tank must meet the requirements of this paragraph as follows:(1) Each tank must have a vent that connects to the highest point of the tank, discharges on a weather deck through a bend of 180 degrees (3.14 radians), and is fitted with a 30-by-30-mesh corrosion-resistant flame screen. Vents from two or more tanks may combine in a system that discharges on a weather deck.(2) The net cross-sectional area of the vent pipe for the tank must be- (i) Not less than 312.3 square millimeters (0.484 square inches) for any tank filled by gravity; or(ii) Not less than that of the fill pipe for any tank filled under pressure.(e)Fuel piping. Except as permitted in paragraphs (e)(1), (2), and (3) of this section, each fuel line must be seamless and made of steel, annealed copper, nickel-copper, or copper-nickel. Each fuel line must have a wall thickness of not less than 0.9 millimeters (0.035 inch) except that-(1) Aluminum piping is acceptable on an aluminum-hull vessel if it is installed outside the engine room and is at least Schedule 80 in thickness; and(2) Nonmetallic flexible hose is acceptable if it-(i) Is used in lengths of not more than 0.76 meters (30 inches);(ii) Is visible and easily accessible;(iii) Does not penetrate a watertight bulkhead;(iv) Is fabricated with an inner tube and a cover of synthetic rubber or other suitable material reinforced with wire braid; and(v) Either,- (A) If it is designed for use with compression fittings, is fitted with suitable, corrosion-resistant, compression fittings, or fittings compliant with SAE J1475 (incorporated by reference in § 27.102 ); or,(B) If it is designed for use with clamps, is installed with two clamps at each end of the hose. Clamps must not rely on spring tension and must be installed beyond the bead or flare or over the serrations of the mating spud, pipe, or hose fitting. Hose complying with SAE J1475 is also acceptable.(3) Nonmetallic flexible hose complying with SAE J1942 (incorporated by reference in § 27.102 ) is also acceptable.(f) A towing vessel of less than 24 meters (79 feet) in length may comply with any of the following standards for fuel systems rather than with those of paragraph (e) of this section:(1) ABYC H-33 (incorporated by reference in § 27.102 ).(2) Chapter 5 of NFPA 302 (incorporated by reference in § 27.102 ).(3) 33 CFR chapter I, subchapter S (Boating Safety).USCG-2000-6931, 69 FR 34069 , June 18, 2004, as amended by USCG-2009-0702, 74 FR 49226 , Sept. 25, 2009