46 CFR §133.135

1. (a)Each OSV must carry at least one rescue boat. Each rescue boat must be approved under approval series 160.156 and equipped as specified in table 133.175 of this part.
2. (b)Offshore supply vessels, as an alternative to the requirement in paragraph (a) of this section, may carry a motor-propelled workboat or a launch if the workboat or launch must meet the embarkation, launching, and recovery arrangement requirements in § 133.160(a), (c), (d), (e), and (f).
3. (c)A rescue boat is not required for a vessel operating on the continental shelf of the United States, if—
   1. (1)The OCMI determines the vessel is arranged to allow a helpless person to be recovered from the water;
   2. (2)The recovery of the helpless person can be observed from the navigating bridge; and
   3. (3)The vessel does not regularly engage in operations that restrict its maneuverability.