I will go back first and look at all my thru hulls to see how they are done. I suspect they are of the "poor" example... as the boat is 30 years old and I doubt the Groco flange type was available or used.

I know there are backing plates... I saw and remember those.

I need to talk to the yard and see what can be worked out. Details man, details.

See, I knew this wasn't a useless thread... Good info here folks.