Sailing life saver
A little idea that can be used in many different cases: part a is close to part b -> nothing happens. Part b moves away from part a -> any kind of alarm starts. This version is for people who love Sailing. If you fall off the boat the alarm of part a rings that loud so other crew member can save you.
The LifeTag starter system, which retails for $685, includes two LifeTags, which have Lithium batteries with a lifetime of 2,000 hours, wrist straps, an alarm module, a base station, and a power cable. If the boat has RayMarine instruments, you'll be able to integrate the LifeTag system into the SeaTalk network and send COB data to all chartplotters and displays.
Via Sailing World
I’ve read that Each LifeTag pendant broadcasts a unique identification code back to the LifeTag base station, telling it that its wearer is “safe.” In the event of man overboard, the link between the victim’s pendant and the LifeTag base station is broken and the alarm is raised automatically onboard the boat.
The lightweight LifeTag pendant can be easily attached to your life jacket, PFD, safety harness or belt. Its featherweight (1.5 ounces) and compact size make it unobtrusive and easy to wear