just completed passage
with AIS Raymarine
500 on Raymarine
is extreemly useful system. It doesn't replace radar/lights, eyes, etc.
But is better than the rest combined.
However, stalkers were able to track me up the coast on internet
sites. and were surprised at my early arrival time. they said my speed was in the 4 to 5 knot
(shtarker)Ve don't do 4 knots here.
So I am thinking it was transmitting boat
speed rather than SOG.
speed was not calibrated and was showing 5 - 6 knots less than SOG in the gulf stream
So, the question is does AIS transmit boat speed/heading or SOG/COG? One is accurate - the other can be completely wrong, and misleading from the perspective of another vessel.
Also if you have receive only AIS - get transmit too - seriously you can be one of the ships or part of a ship...