Sanding/Varnishing

[Whitworks]

I have 2 coats of 105/207 on the interior for a non-slip glass weave texture. Will apply 3+ coats of semi-gloss varnish. Planning a light wet and dry prep with a 150/180 grit with a weak detergent solution followed by a thorough rinse (have the feeling that Sedges would recommend an ammonia solution before the rinse) and a tack cloth wipe. This will obviously only roughen the high points of the weave and I'm wondering if varnish adhesion to the low points is problematic.

As far as varnish is concerned, it's hard to find a consensus on what's best. I'm leaning towards Defthane or Interlux two part polyurethane but they are very expensive and, apparently, are not recommended for below waterline application (although I have the feeling that applies for boats which are docked or moored). I remember seeing a link to a long-term brand comparison test between varnishes but can't find it, and there might have been more developments since that test anyway.

Would appreciate any updates/opinions.

Cheers

[Whitworks]

Found the link to the varnish comparison test and other useful input from last March on this forum. Not likely that much has changed since then. Looks like Epifanes has a few fans; will check it out.

[Glen Smith]

Epifanes is my favourite.
Edit: Epifanes has an amber tint so if you want something clear you should look into other choices.