I just got my renewal notice from Newton Crum. Whilst I was pleased to see no increase in premium from last year, my eye was caught by a line:
"IMPORTANT REMINDER this insurance excludes craft fitted with HYDROFOILS or FOILING/WINGED RUDDERS"
Oh my, I think, so I give them a call. After a little discussion at their end, my having pointed out that a 12 with a winged rudder (even if retro-fitted) is indeed faster than one without but not that much faster, they confirmed that sailing with a winged rudder would invalidate any insurance that they provide.
I checked my insurance documentation from last year and there is no mention of this limitation.
I am now off to secure insurance elsewhere but it might be advisable for you to check your insurance in case there is any such limitation in the small print.
Thanks for flagging this Roland!