EPIRB (type that triggers when submerged, or switched on) do not have a very long antenna, are short range.  If you are talking about Commercial Shipping Grade  EPIRBs, those are attached to an Antenna that is mast mounted really high up, sensors are mounted at locations on board that are not normally exposed to water, on the ships bridge there is a switch that is a test switch and an activation switch (also turned on during Pirate Attacks, or abandon ship).  They got "lost" because they did not know Basic Ocean or Sea Navigation, only Littoral sailing within visual sight of Islands.  The only thing they did right was the year of provisions and a water purification system, the not so right things were no backups, and no water still to turn salt water into fresh water.  Serious lack of knowledge (life endangering) of basic engine repair, rerigging, steerage repair, Emergency Sea Distress Signals, repairing a salt water soaked or damaged transceiver, rigging an emergency antenna.