Hey Austin.
So there is a wide variety of means by which we are alerted to persons in distress. The distressed persons themselves or a Good Sam (Good Samaritan) coming up on 16 or a cell phone is probably the most frequent method in my AOR: Lake Erie-and Western end of Lake Ontario. It's unfortunate that many recreational boaters don't have at least a portable marine radio with them.

Pyrotechnic or other visual signaling devices seen on shore or by other boaters and reported to the command center are probably the next most frequent method in my AOR.

EPIRBS (Electronic Position Indicating Radio Beacons) or PEPIRBS (Personal Electronic Position Indicating etc.) are not as common. EPIRBS usually are rigged to automatically detach from the vessel and activate if the vessel goes down. They are generally found on commercial vessels or larger recreational vessels. When the larger vessels get into trouble there is usually time for the skipper to ask for help before the vessel founders. I don't recall the last time the activation of one of those devices was the first indication of a distressed mariner. We get PEPIRB activations from time to time, but they are almost always accidental false alerts by folks who think they are testing the batteries or kids who are playing with them.

When I’m doing surface ops I always carry a standard Randall Made™ Model #15 in stainless with saw teeth. I inlaid a regulation coxswain device into the handle on the trademark side and the shop etched my name, unit number and EMPLID (Employee ID=Serial Number) on the off trademark side. The sheath is a riveted black sheath that Greg Gutcher made for me when I bought the knife from the shop.
When I am flying (aircrew) I carry a Benchmade automatic knife in my flight suit. I also carry a lime green wetsuit head covering and dye marker powder if I wind up in the drink and still alive and conscious. Our standard issue life jacket has manually operated pyrotechnics, signal strobe, and PEPIRB. The aircraft is equipped with an ELT (Electronic Locating Transmitter).

Regards,
Doug