An explanation of the many new features in this release is available on http://opencpn.org/ocpn/release3.0.
A very interesting feature is the support for Ais SART, Search and Rescue Transponder. If the crew uses personal SARTs the normal AIS receiver can be utilized to pinpoint the MOB and every other vessel in the vicinity, will also be aware of the emergency and the location of the SART.

The weak link here is that not many on board plotters (on other vessels) yet recognizes the AIS SART special nmea sentence, and displays the SART target, as a normal Ais target. Including the MMSI number + position of the SART in a mayday call will help in this case.

Way superior, to the present on board mob tracking devices on the market.