So very sad to hear. Always remember her auctions for the Chesterfield canal society.

It's a good idea to have the walls below the gunwales at 90 degrees to the floor. It makes it so much easier to fit, for example, kitchen units. I have levelled off the walls in the manner you propose. We don't have spray foam insulation, but slab roof insulation with a vapour barrier. However, the gap you refer to is there in our boat, but I've never had the slightest problem with condensation in the gap.