Questions about Fairing Compounds

[Mark42]

I see iboats has a high performance fairing filler by 3M for below the water line. Its rather expensive. Seeing as my project will be above the water line, I figure the "standard" fairing compound they have should work:

But its just regular auto body filler. If I use this, will gel coat stick to it as the final surface application?

What have you guys used for fairing compound?

 

[KnottyBuoyz]

Re: Questions about Fairing Compounds

SystemThree QuickFair

Mixes easy, spreads easy, dries quick, sands easy. You can easily get 3 fairing sessions in in one day.

 

[1730V]

Re: Questions about Fairing Compounds

Bondo sticks to fiberglass just fine but it will degrade below the water line. Ask me how I know this?

 

[Mark42]

Re: Questions about Fairing Compounds

Knotty, System Three is all epoxy, right? I want to stay with polyester products.

1730, Yeah, know bondo sucks up water when soaked in it. But it seems that bondo fillers are common fairing compound. I really don't have a problem using it above the water line, but I want to be sure it is an accepted practice and provides a good base over the glass work for gel coat.

 

[EricR]

Re: Questions about Fairing Compounds

I used polyester based filler by Evercoat on several spots on my boat, four years and not cracks yet. And no, it has not sat in the garage on the trailer for four years.

 

[KnottyBuoyz]

Re: Questions about Fairing Compounds

Knotty, System Three is all epoxy, right? I want to stay with polyester products.

Epoxy based fillers will work over polyester resins just not the other way around. You're wise to choose a system and stick with it. I'm not familiar with any marine poly fillers. Quickfair seems to be compatible with most paint systems. I've heard over and over how good it is to work with. I remember sanding and sanding and sanding bondo and it's not pleasant. Probably the worst part of the job ahead of you! ;-)

 

[pgdignan]

Re: Questions about Fairing Compounds

West system has all kinds of fairing compounds, high, medium and low densities (they also have that silica compound that makes the epoxy harder than granite). I've used the evercoat stuff (kitty hair) as well and it seems to work for high build areas. Personally I've never had any luck with Bondo.

 

[BillP]

Re: Questions about Fairing Compounds

The lowest priced ($25 qt) polyester non structural surfacing putty I've found is the west marine brand. I used it last yr on a sailboat cockpit to "glaze" out major stress cracks and a few 1/4" deep gouges. It worked good can be used above or below the waterline. They also have the same stuff with fiberglass fibers mixed in and call it structural surfacing putty. Several yrs ago I used the Evercoat filler and it worked good too. Never tried the 3M filler. It costs about double everything else...but you know 3M is the best.