Submersible finish required

[Fumbler]

Team, I have made a contraption out of Jarrah, Paulownia and Cedar, it is for use in salt water. What finish is best to use? it needs to have the following characteristics.

1. waterproof
2. durable/long lasting
3. non yellowing
4. light as in weight (if fiberglass or epoxy resin is suggested)

All recommendations considered

[ian]

2 pack marine "varnish" or tinted finish. You'll need to visit a ship's chandler or marine supplier

[ian]

oh, and if you need impact resistance, you'll need to fibreglass the "contraption".
Seek additional advice, but I would think that 6oz cloth (6 ounces per sq yard) would be heavy enough.

[Arron]

I don’t think you can go past marine epoxy - just the epoxy, not epoxy and glass cloth unless you want a sheathing. It will yellow, everything does, but if you choose a ‘non-yellowing’ formula it will be tolerable. Your other 3 boxes it ticks quite nicely.

Cheers
Arron

[Fumbler]

Cheers boys, I think i'll go with the marine epoxy, and just make it a thin coat. i'll post pics when finished.

[Arron]

I should have pointed out that marine epoxy is generally not self leveling, so the strategy is apply the epoxy, sand it smooth, then apply a marine varnish. The epoxy is needed because the marine varnish isn’t particularly waterproof, no varnish is. The varnish is needed because sanding the epoxy leaves a cloudy finish, varnish it and it goes back to being a smooth transparent surface - like magic.

It doesn’t have to be done this way, it depends on how important aesthetics are and whether you want a smooth finish or not. You can just use the epoxy, but it will be a bit lumpy, not slick like a racing yacht.

[ian]

Cheers boys, I think i'll go with the marine epoxy, and just make it a thin coat. i'll post pics when finished.

don't make it too thin or it won't be waterproof.

It's many many years since I used a two-pack marine finish, but my recollection is that the finish was self-leveling.
examples:
https://www.whitworths.com.au/pnt-uc-perfect-1l
https://www.whitworths.com.au/pnt-p-top-white
I'll leave you to explore further

[Fumbler]

I might actually pop out and see a mate who makes surfboards and see what he suggests. will let you all know how I go.