Fairing fillers

[OV1961]

Has anyone used West System 407 or 410 fillers?

I began stripping off the anti-fouling paint that is on the below waterline part of my hull. There are zillions of scratches, some deep and into the fiberglass, in the gelcoat. And the gelcoat is very cracked/crazed like the look of a shattered auto windshield. Decades of water skiing and beachings took it's toll.

The 410 is supposed to be easier to sand, but I want to make sure I fill the gouges with something strong. Should I go with a bonding filler like 403, which I have currently, and squeegee it tight on the hull to minimize sanding work?

OR, go with a polyester filler. I have a can of West Marine's "marine structural filler" that has fiberglass strands in it. There is one hull repair area that I would have to avoid though.

 

[erikgreen]

Re: Fairing fillers

Depends on what you need.

I personally use 3m glass microbubbles for filling anything that's not structural, or that I might want to sand smooth.

I use wood flour for structural fillets, or if I really need strength, then fibers too. That's for working wet on wet, when I don't need to sand.

If you put strands, cabosil, or to a lesser extent wood flour in your epoxy or poly, you'll have a heck of a hard time sanding it.

From the sounds of it you have a lot of little spider cracks... you're not going to be able to do anything but cover those up (and then they'll reappear pretty quick) unless you grind them out a little, down to the bottom of the crack in the center, and grind out to the sides enough to give whatever new material you use something to grab onto.

You don't need to worry about strength, especially if you're using epoxy. I'd concentrate more on how much you'll be sanding to make it fair.

If you get a particularly deep crack or repair (down to the glass) then start with the fiber based stuff and finish with a layer of sandable.

If you're just covering cracks and gouges, then just use sandable filler, and do the prep work first.

Erik

 

[oops!]

Re: Fairing fillers

erik is exactally correct.....sanding epoxy is like sanding cement......and there are no easy sanding epoxy fillers, ....

the words.......sands like butter and epoxy are used often in the same sentance.....but never around the boat.

is you have an 88 that suffers from heavy crazing you have different problems than pulling it on the beach.

you can use a gellcoat paste.....or even straight gellcoat.

getting the color to match is what will be the hard part.

cheers
oops

 

[OV1961]

Re: Fairing fillers

I am not going with a gelcoat repair after the filling in of the gouges. It's going to be painted with INterlux. And of course it's on the bottom where no one will see it, so I'm not worried so much about perfect fairing. I'll buy some of the micro bubbles for my epoxy. Thanks!