46 CFR §130.440

1. (a)Each OSV must have a communications system to immediately summon a crew member to the machinery space wherever one of the alarms required by § 130.460 of this subpart is activated.
2. (b)The communications system must be either—
   1. (1)An alarm that—
      1. (i)Is dedicated for this purpose;
      2. (ii)Sounds in the crew accommodations and the normally manned spaces; and
      3. (iii)Is operable from the pilothouse; or
   2. (2)A telephone operated from the pilothouse that reaches the master's stateroom, engineer's stateroom, engine room, and crew accommodations that either—
      1. (i)Is a sound-powered telephone; or
      2. (ii)Gets its power from the emergency switchboard or from an independent battery continuously charged by its own charger.