I had the same problem.

We have an Aquasignal combined masthead tri and anchor light, and I fitted a 10W equivalent LED for the anchor light several years ago with great results and no problems - it means you can leave it on all night and ignore the current drain.

I eventually got a 25W equivalent for the tricolour fitting, and had exactly the same problem. The manufacturer said I was the only one to experience this, which seems unlikely. However, I do know that the McMurdo DSC set we have is particularly sensitive compared to most sets on the market today (was told by a former McMurdo tech guy) so perhaps it is dependent on the VHF set.

We eventually gave up and went back to the standard bulb, but is anyone comes up with a definite fix for this PLEASE PM me as I hate having to run the engine unnecessarily when the sailing is good!

Anyone wants to know which brand of LED was involved can PM me.

- W