The flanges are deeper than the thickness of the plywood, so they intrude into the bow compartment and the centre board case by several millimetres.
This doesn't really matter in the bow, but it does in the centre board case where the ports could foul the board.
When I first became aware of the problem I thought I would grind away the inside edge of the flanges, but on reflection I thought that would be an ugly solution and could leave sharp edges in the centre board case - which would be dangerous if I had to get my hand in there to fix something.
Furthermore, the fixing screws for the ports are slightly longer than the thickness of the ply, so would also protrude. Which is really bad news where there is a lot of water sloshing around inside the case!
So that was that. I needed to make some gaskets on which to mount the inspection ports.
I decided to use some scrap 6mm marine ply, and tacked three pieces together at their corners with the glue gun to make a ply 'sandwich'. Here is the sandwich, with the glue gun and the flange.
First I marked out the inner circumference of the gasket by scribing round the flange. See above.
Then I made a starter hole and cut out the inner waste with the jig saw.
I cleaned up the aperture until the flange was a drop fit, and marked out the outer circumference.
Again I made a starter hole and cut out the gaskets themselves. Here they are.
Three identical ply gaskets! Then I cleaned them up with a Shinto saw file and the SpiraBand abrasive wheels, which are perfect for this sort of task. Like this.
The gaskets then received two coats of clear resin to seal them, as here. I made a gasket for the drain bung in the bow compartment as well, seen below.
I then hand sanded them to a P150 finish.
Next they were test fitted. Here they are in the centre board case ...
… and here in the bow compartment.
I pencilled in the outer circumference of the gaskets on the boat and sanded the paint to provide a sound surface for gluing them in place. At the same time I taped them off with blue tape to prevent the epoxy glue from making a mess of the paintwork.
Here is the bow compartment.
And here is the port side of the centre board case.
Finally, the gaskets were all glued in place with thickened epoxy. Here is the gasket in bulkhead 1, clamped up and curing with tape removed.
And here is the gasket in the starboard side of the centre board case, clamped and curing.
And last but not least, of course, this is the drain bung gasket curing. I have inserted the fitting to hold the gasket in place.
So that's that. Next step is to fit the inspection ports themselves. Exciting!
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