Refinishing a Fiberglass Hull

I have a 1992 f/g Mad River Malecite. It was in rough shape when I got it back on 03 or so. I have just finished a rebuild of the gunwales. I now want to look at doing something with the hull, it’s oxidized, has some stars and cracks in the gelcoat. It also has many scratches and needs some attention to the bow and stern ends, probably skid plates. I thought about wetsanding it and laying a few coats of spar varnish on it hoping that would bring it back but was advised against wetsanding gelcoat.

I found this link about working on a hull:

At this point after searching the web I’ve decided that there is just too much information which has jumbled my gray matter to the point I’m not sure where to start. I’d really like to keep this ol’ hull going for a few more years.

So, who out there has some experience working up old hull to make them look good and fix any kind of imperfections in the gelcoat and would be willing to share? Many thanks in advance.


I am ALSO rebuilding a Malecite
I am presently rebuilding an old F/G Malecite that was “HANDS DOWN” the ugliest canoe I had ever seen a few months ago when I bought it. It had eight bullet holes on both sides in a tight grouping near the waterline near the bow. This was patched from the OUTSIDE with cheap woven fiber and gobs of resin. It had been painted THREE times over the original maroon. First BLACK,…then garage floor Grey, then camoflauge. It had rotten 2x2 gunwales with plywood decks and plywood slat-board bench seats. It was the ultimate REDNECK duck-huntung machine. Now about 60 hours of work later,…the canoe has factory black aluminum gunwales,…custom black/green web seats,…the redneck layers of paint had to be removed with a power sander and 60 grit sandpaper being VERY careful not to cut into the gelcoat too much. After grinding off the old patches,…I applied NEW tight cloth fiberglass patches over the bulletholes from the inside and filled the holes from the outside with Bondo Ultimate Autobody repair resin. It had a few more small near-punctures that needed application of the bondo and the entire hull had severe spiderweb crazing of the gelcoat. I went ahead and wetsanded the whole hull down with 150 grit to virtually eliminate the spiderwebbing and that is were I am at this point. I am now planning on spraying the entite hull with an autobody primer/filler then wetsand it down with 320 grit to hide the spiderwebbing so it will be ready for a quality finish. I am actually considering a two-tone paint job divided at the waterline,…and after learning more about Garage-Floor paint (and how incredibly difficult it was to remove), I might make the BELOW waterline color from this extremely durable type of paint. What do ya think?

dougd, that’s a Souris River canoe …

– Last Updated: Sep-07-10 12:54 PM EST –

...... it doesn't have gelcoat . The guy says the hull is still strong even after all the UV exposure , so maybe it is , maybe it isn't ... only use and observation will tell that . It's not surprising that it was able to be sanded down (that's fiberglass cloth on the exterior) , it's not surprising it's color looks similar to original restored (that's aged kevlar cloth underneath) , it's not surprising he just sanded it with 80 grit and rolled a thinned coat of expoxy over it (that's a standard barrier coat application) ... I would do a Souris River the same way , only I might finish with a couple coats of marine spar varnish either over the epoxy barrier or without the epoxy (if no epoxy , then 2nd (final) sanding w/ 150-180 grit) .

You have gelcoat , so if you are willing to use a good quality 2K paint ... then it's just a matter of sterilizing the hull by wash/scrub and rinse , then good acetone cleaning , then start in with 80 grit (dry) intire hull sanding ... any more serious areas of gel damage or structural damage will need special attention to prep. for repair to come ... then start in with the filling and fairing (I like 3M Premium Marine filler (a vinylester) ... sand filled areas to fair (repeat filling and sanding as and where needed) ... always wipe down the area of work with acetone before and after sanding , you can't use too much acetone , buy a gallon can , use heavy rubber gloves and also have a 25 pack of disposable (nitril , latex , ect.) gloves on hand too) ... when you think your hull is filled and faired to your liking ... give it a primer coat and sand that to fair with 150-180 grit ... acetone wipe down and then paint it with a good 2K paint .

If you have stem wear and tear that you want to fix up , do that with fiberglass cloth strips and resin , fair those in as needed while you are doing the other prep. (fill and sanding work) before primer and finish coats .

You can also use some "finish" gelcoat (cures exposed to air - no covering or wax needed) here and there for filling and sand it to fair (use it as a finer filler) , paint it on and sand it off , use both the gel and the 3M where ever you want . The object is to fill and fair before prime and finish coats .

Keeping the work surface area sterile with the acetone wiping is a key to best adhession of filler and gel . They will stick (and stay stuck) where you put them .

With any filling and sanding , no matter what materials (resins and fillers) you are using , the idea is basically shaping and smoothing with the sand paper (fairing) . Think of it like you are a sculpter using sanding to sculp) . I use a Dewalt Random Orbit sander (have job packs of 60-180 grit hook & loop disc papers on hand) , have 80-320 sheet papers on hand , and finer wet/dry papers as needed (you won't need finer wet/dry papers for what you want to do) .

I also use wood blocks that I wrap the sheet sand papers around , also use other wood shapes (wraped w/sand paper) as needed for special contour areas .

It's not a big deal , but does take time , money and patience ... if you decide to get into it , great , just keep going until it's finished . A canoe is a little thing , not that big of a job .

What do you want to do ??

First do NOT use bondo, it absorbs water.

If you want to fill cracks etc, use thickened epoxy.

Prep is 95% of the work. If you want it to look like new sand the boat down smooth, fill in cracks etc. with thickened epoxy. Sand down again. Paint with primer for 2 part urethane paint. Sand again, then using a good roller and a good natural hair brush do a “roll and tip” paint job. You can look it up on the internet. Basically you roll on the paint, then tip out with the brush. If it is done right you will have a very nice finish.

Let’s bump this up. Pnet has some
really good gelcoat people who can give more info.

If the hull is functional and the gelcoat cracks are the usual fine star cracks, I would just keep paddling the boat. A general sanding and polish might be enough. I’ve coated non-gelcoated fuzzy hulls with epoxy, but it does not work that well and while epoxy WILL stick well to gelcoat, it’s an ugly fix.

That’s why if you fill with epoxy you have to sand, prime and re-paint. Proper boat hull paint (two part polyurethane) properly applied to a WELL prepared hull will give you a good finish. Re-applying gel coat to an entire boat is a much more difficult job to do right.

If you want that “like new” look, you have to do the entire hull.

I have done 2 sailboats this way. (probably as much glass as 50 canoes). Many boat repair yards use the roll and tip method instead of spraying. Granted, when done you might need to buff the paint to make it perfect. Its all in the prep!

I’m following this too
I’ve got a Malecite that I’ve got to re-rail. I has some cracked gelcoat too. If it’s not too expensive and time consuming, I’d might do a cosmetic job on the hull too.

How expensive is that two part paint? And what kind of colors does it come in?

Not Gelcoating
No way am I gelcoating, too much work and I don’t have the place to do such a job. I’m looking at the oxidization issue and the cracks/stars in the gelcoat. It will paddle fine as is but think this should be payed attention to to protect from further UV harm and just plain old age.

I’m not real concerned about the scratched, plenty of those but some kind of extra coating would be nice to help quell further ones,and covering the older one up higher on the hull/around waterline would be nice. I will need skid plates but that will be a spring project. If you saw how I do resin work you’d drive here and do it for me out pity! :wink: Thanks for the suggestions so far. Will be putting up pics later this week.


Not cheap but you won’t need a lot. Basically any color you can think of.

There you go old chap
Any further questions please ask.

If you decide to just paddle it
try Nu Finish…available at auto parts or big box stores. It will remove a lot of the oxidation and make it shine. It is a polymer, not a wax so if you decide to remove it to paint over the hull it may be a job…not sure how you would do that.

Try this only if you decide refinishing is not necessary at this time. Works great on my boats and takes about 15 minutes.