46 CFR §169.555

1. (a)Each vessel certificated for exposed waters must have an approved Class A emergency position indicating radiobeacon (EPIRB), and each vessel certificated for partially protected waters must have an approved Class C emergency position indicating radiobeacon (EPIRB). The required EPIRB must be—
   1. (1)Operational;
   2. (2)Stowed where it is readily accessible for testing and use; and
   3. (3)Stowed in a manner so that it will float free if the vessel sinks.
2. (b)Each vessel must have an additional Class B EPIRB for every twenty-five persons onboard, for use in the lifeboats and liferafts.