What should I use???

There is marine bondo type stuff. Premade from resin and various additives - or make your own.

Cabosil is extremely hard and hard to sand. Phenolic glass beads is easier to sand.

I have used this http://www.fgci.com/bp_viewproduct.aspx?itemnum=134012&oldItem=134012 with good long lasting results.

 

slide on over to walmart and pick up some fiberglass bondo in the automotive section, i've had pretty good luck with it

 

Not an expert but QuickFair by System three is what alot of guys use on thier Bateau builds. It was easy to mix, spread and sand for me first time use.

 

you may want to check the "contents" on that can of "bondo" - what you're looking for is "talc" - if you see that in the contents list don't buy it..."talc" absorbs water...

"quick fair" is good stuff

 

auto bondo is NO GOOD for marine use - period!

The product I posted is in the putties section www.fgci.com go to online store, puttys- epoxy and polyester, polyester fairing, super poly fill.

Quick fair is good stuff but expensive.

 

x2 on the Bondo, even the fiberglass reinforced body filler will absorb water. I would grind it off to avoid possible cracking issues later on.

Quickfair is good stuff, but expensive, and you have to sand it down inside a certain time frame or else it will cure hard as a rock and be difficult to work with.

Assuming the imperfections are very minor, like shallow scratches and not deep gouge marks, then you can use some fairing mix from your local West Marine. Granted it's not my favorite store but it does come in handy at times. I've used West Systems low density filler and it works great. Just mix it with your resin until it's about peanut butter consistency, it sands easily and a little can go a long way.
http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productId=14893&catalogId=10001&langId=-1&storeId=11151&storeNum=50218&subdeptNum=50219&classNum=50222#.URukyqU8CSo

 

How long do you plan to use this boat?

And what are you covering up the filler with?

I've used bondo and other lightweight polyester based filler with good luck. The last skiff was heavily fished for over 4 years with no signs of problems when I took a chain saw to it.

If you cover the bondo or polyester based filler with a good paint or gelcoat and don't plan to keep you boat in the water 100% of the time you should be fine.

 

That is what I meant by making your own filler. Be prepared because epoxy and cabosil is like sanding concrete, hence why I posted the filler I like.

 

On the lifeboat repairs, we used a lot of super poly fill. It got the job done quick and easy. But if it was too deep, we first used resin, cabosil, and chop to fill in the void, sanded that down, and then finished off with the super poly fill.

 

I meant, how many times a week or year do you plan on using it?

Most people are worried about fillers and resin taking on water and they then use their boat 1 or 2 times a year while it sits on a trailer the rest of the time.

It sounds like you're on the right track. Use the epoxy if you have it. Call the epoxy manufacture and ask them what filler additive they recommend.

 

if you like spending extra money frivolously awlfair is good, bondo is just as good in my opionion , but the gold series if by far better than even west system with cabosil and significantly cheaper,,yes cheaper is better in these situations! and its easier to sand, the awlfair is actually fairly easy to sand, all epoxies fairing compound with the exception of awlgrips spraying highbuild fairing compound are very difficult to sand and leave pits, with bondo gold premium,no small craters, but if they do wet a thin layer of resin over it!