46 C.F.R. § 28.325
Fire detection and alarm systems
(a) Each accommodation space must be equipped with an independent modular smoke detector or a smoke actuated fire detecting unit installed in accordance with 46 CFR part 76.
(b) An independent modular smoke detector must meet UL 217 and be listed as a “Single Station Smoke Detector—Also suitable for use in Recreational Vehicles.”
(c) The regulations in this section have preemptive effect over State or local regulation within the same field.