ABYC standards are voluntary. 33 CFR 183 is US federal law, written for boat builders, and free to read. For a gasoline boat's fuel system it's the most precise benchmark a surveyor has, and the one ABYC H-24 sits alongside.
What it covers
Section 183.501: "This subpart applies to all boats that have gasoline engines, except outboard engines, for electrical generation, mechanical power, or propulsion." The subpart defines the fuel system as the whole assembly of fill, vent, tank and distribution parts, including pumps, valves, strainers, carburetors and filters. It's split into equipment standards (tanks, labels, vents, valves, fittings, clamps, hoses), manufacturer requirements (installation of each), and tests for tanks.
What surveyors check against it
Hoses, 183.558. Pump to carburetor: "USCG Type A1". Tank to engine: A1, or B1 where no more than five ounces of fuel is discharged in two and a half minutes in the drainage test. Vent and fill: A1 or A2, or B1 or B2 under the same test. Each hose secured by a swaged sleeve, a sleeve and threaded insert, or a hose clamp.
Anti-siphon, 183.568. Each line from the tank to the carburetor must run above the tank top, or have an anti-siphon device or electrically operated fuel stop valve, or, where the tank top is below the carburetor inlet, be metal line or Type A1 hose with one or two manual shutoff valves. See missing anti-siphon valve.
Foam round tanks, 183.516. Foam used to encase metal tanks must not absorb more than 0.12 pound of water per square foot of cut surface, among other limits. Wet foam holds water against the tank; see fuel tank corrosion.
Citing it in a finding
Name the section: "fit an anti-siphon valve or electric fuel stop valve at the tank withdrawal fitting, 33 CFR 183.568". For a diesel boat, cite ABYC H-33 instead; subpart J doesn't apply.