Each signaling system that interacts with the outside world — whether a satellite messenger, an EPIRB, a PLB or simply an MMSI number for a VHF radio — requires registration. This is essential if the rescue device is going to do its job. Registration can be done by mail or over the Internet. Don’t put it off. Instructions come with the gear you buy. In most cases, online information can be edited at any time. Before a big trip, for instance, you can go online and add your destination and plans to create a de facto float plan. Then if you have to push the SOS button, rescuers will have that much more information about your whereabouts. Be sure to change back the info when you get home.