[MarkofSeaLife]

It's not just "cheap" overseas LEDs. Mine is AquaSignal and they drop my AIS reception down a lot.

 

[MarkofSeaLife]

Can one do a work around by turning the tricolor off and see signals appear and then back on again? Or is this simply blocking weaker distant signals?

Yes. Its exactly what I do to test it. But it takes up to 6 minutes to get all ships transmitting. Its not instantaneous.

My masthead tricolour is only an emergency nav light. My main ones are at deck level. When I turn on the mast head nav lights they cut reception from 20nm to 10nm. Thats a substantial amount.

I cant tell how much it cuts my transmission. I have tried on many occasions to ask other cruisers and passing ship how far my AIS transmits but no one understands. I mast have extremely stupid friends.

Mark