Best fairing compound for below the waterline?

[mrybas]

I’m doing a complete bottom job on an epoxy cat. I’m stripping old paint back to glass, then fair, barrier coat, and Copper Coat bottom paint.
I want to use an epoxy based fairing compound. I was thinking either West System with 410 Microlight additive or Interlux Interfill. Any recommendations?

[Matt Johnson]

While you can mix your own (I would buy cheaper phenolic microballoons than West like this), it's much easier to use Alwgrips AWLFAIR. The issue I had with mixing my own was trying to get consistency the same from one batch to another. Some would trowel on easier and some would sand faster. The ratio stayed the same of filler to epoxy, but they always just felt slightly different. Awlfair was perfect right out of the can.

Matt

[hobopacket]

Yeah. I agree. I did a complete gut and refit of a little skiff. I did mix my own for all the fillets for stringers and the deck. But for the bottom I used a premixed fairing for a easier sanding. Worked great. I used a 3m product.

[fkittson]

I have been doing this for years and the best thing ever is west with 407 filler. It sands perfect like butter even if it is mixed thin. Don’t listen too what the internet say, anytime you add a filler you will need a final coat it interprotect 2000. As any filler added will absorb water even if the base is epoxy.

[44'cruisingcat]

Depends on the size of the job. If there's a lot of fairing to be done, then phenolic microballoons. If it's just nicks and dents, then a commercial fairing compound.

[kenbo]

I come to like System Three QuikFair epoxy fairing putty. Easy to mix and get consistency and sands about as easily as any epoxy putty I've ever used.