Having spent a long time in the Coast Guard before EPIRBS I can tell you finding somebody is critical to saving them. Time is a major factor live or die. At extended distance time searching is often limited by the Helo's range. You might remember the Replica Bounty sinking. They were at the extreme range of CG Helicopters, able to fly direct to the sinking vessel following a good EPIRB signal.

I can't tell you if Marine intended EPIRBS are responded to by the Coast Guard when activated on land. Or if somebody else monitors the signals.

Boats