I am removing all thru-hull fittings that also have seacocks. Here is an example (first picture I've tried posting; hope it shows below) of the current installation. Notice that the thru-hull fitting is mounted on the outer hull. The hull lining and core material are cleaned out. This does not seem like a correct installation. I plan to fill in the core and glass it to make the hole flush with the inner hull surface. Then I will mount the thru-hull as described by others in this thread. Is this an "uncommon" installation? I wonder if Beneteau mounted in this manner or if this is an after market installation?