46 CFR § 120.370
General grounding requirements
April 15, 2021
(a) A vessel's hull must not carry current as a conductor except for the following systems:
(1) Impressed current cathodic protection systems; or
(2) Battery systems for engine starting.
(b) Receptacle outlets and attachment plugs for portable lamps, tools, and similar apparatus operating at 100 volts or more, must have a grounding pole and a grounding conductor in the portable cord.
(c) Each nonmetallic mast and top mast must have a lightning ground conductor.