Sanding epoxy

Not exactly my idea of fun but it has to be done.

I was going a little back&forth with this: which system to use for painting inside of the hull.
For one part I had no doubts: it has to be primed with epoxy. I did not manage to roll two layers, as I planned, but one layer is enough as a primer and veneer stabilizer.

Now - this constant debate about epoxy vs other paints is of no interest to me. For me it is no brainer: plywood is not a solid timber and needs to be treated with epoxy to hold long.
Just a question of how many layers and what will be painted on top of the epoxy. Ian Oughtred, in his book, strongly advocates against using epoxy in favor of oil or varnish/paint system. My practice has shown that with epoxy, at least as a primer, the plywood holds much longer and is very stable. Geoff Kerr in his series about building Caledonia Yawl is of the same opinion.
But that approach requires a bit more work at the building process. Quite a bit.

It took me a whole day and there is a small bow-section left to be sanded. I’ll finish that tomorrow.
The aim with this work is to knock down wood grain (hair) which rose after rolling the epoxy plus some air bubbles and generally rough surface. And to get rid of amine blush which is inevitable when using this stuff. I use only WEST system 207 hardener which blushes very little but still enough to inhibit any paint to sit well on top.

Wet sanding is my preferred way of dealing with it. Not only I avoid nasty dust but also remove amine (which is solvable in water) in the same operation. And you get a lot of more mileage on your sandpaper! I use 120 grit, it is coarse enough to knock down bumps rather fast and fine enough to leave smooth surface with just enough keying for top coat to grip into it.

There is only one drawback: you cannot paint just after sanding. Should there be any water which reached into the wood/plywood: sealing it with paint will risk rot. I usually leave the boat for a few days in summer temperature so that any excessive humidity has a chance to evaporate before I seal all with paint.
After wet-sanding excess water is removed with a rag and I leave the slur to dry, to vacuum it before final washing with fresh water and clean rags.

I decided to paint the bilge with International Danboline bilge paint (because I have a stock of it and it is a good stuff) and varnish all the rest with Epifanes (for the same reason). Flotation tanks will get additional two layers of epoxy and no paint - they sit in the dark so no need to coat epoxy with anything.