re-doing gelcoat

-- Last Updated: Aug-04-10 4:34 PM EST --

I am thinking of re-doing the gelcoat on a couple of my boats. Any recommendations on gelcoat, and is there some kind I could brush on and wetsand/buff to a smooth finish? I don't have a sprayer.
Right now the boats are white, one would be redone in white, and one I want to change to a bright lime green, like the old Dodge Chargers from 1969.

PS. Also, would there be any advantage to using gelcoat VS using marine paint such as the type used on sailboats?

Gel coat.
Gel Coat will not setup in the presence of oxygen. You have to spray a coat of wax over the top once you have applied it. There is a liquid wax made for that but I can’t remember what it is called right now. The biggest thing, like any refinishing. It’s 90% in the prep work. You need to have a day that isn’t too hot, not much wind and average humidity.

Now if you want a simpler method, why not use a 2 part linear polyurethane paint(boat paint, car paint). it’s a very stable finish and is easier to apply.

Actually one cn, but…

– Last Updated: Aug-04-10 8:43 PM EST –

We've re-gelled broad swaths of outer gel without wax overlay. Just wipe, and wipe again with acetone. That said, the project, replete with copious sanding to 2000 grit is seldom worth the time and elbow grease on an old hull.

I'm a bog fan of painting. Here's how:

A New[ish] Bottom

So your composite paddlecraft is scratched and noticeably slow in the water. One can re-resinate the bottom of skin coat boats or re-gel the bottom of gel coated boats but those are very long processes that require lots of sanding. Here’s a simpler plan more in keeping with maintaining a used boat.

Acquire 120 and 220 grit sandpaper, a very short section of 2X4, a new Sharpie, plastic and masking tape, yesterday’s newspaper, a couple cans of high grade spray enamel and something to fill scratches. Ideally, we fill with the manufacturer’s laminating resin if the hull is skin coated or gel coat if gel coated, but Bondo from the auto or hardware store works well too. Find 4 foam blocks and a few rags.

When selecting bottom color, light colors, off-white, beige, tan will show successive scratches less than darker colors like green or red. Select a known brand of enamel so color and formula are repeatable.

Find the straightest, most level concrete or MacAdam surface available; probably a parking lot. Which may require a short drive with your hull on the car. Carefully place your hull on the surface, blocking it upright with the four small chunks of foam, keeping rails/cockpit rim parallel with the surface. Check this with a bubble level.

Tape a Sharpie/Magic Marker to one short side of a 3” block of 2X4. Keeping the other short side down on the parking lot, move the Sharpie around the hull, marking a ~3” waterline. Load your boat and go home.

Place the hull upside down on saw horses that, mindful of overspray, are not close to your house or automobile. Sand any proud areas flush and clean any deep gouges with acetone, filling with the medium you have chosen.

After the fill has hardened, sand those fills flush with 120, then 220 grit. Clean the hull with acetone, careful not to wipe the marked waterline off. Lay a line of plastic tape along the marked waterline. Then tape newspaper along that tape line with another line of masking tape to protect the upper hull surface.

Spray paint the bottom, pulling the masking tape[s] off quickly so the waterline edge is still wet when the tape is removed. Wipe off any overspray or runs off with acetone on a clean rag.

The new hull surface will be about 2 mils rough, not quite as smooth as the 1 mil roughness of new gel coat, but way slicker than the ~40 mil roughness of a scratched hull. And, touch ups are easy with the can of spray paint.

I got in over my head stripping gelcoat and a bad deck paint job on my Explorer.I didn’t have the equipment, space, or time so I found a small shop to paint it and I am very pleased with the results. Slick as glass and I think tough too, it fared well on a concrete ramp, broken shells, but no oysters yet.

My ten year old boat looks new again

to do a full re-gelcoat job …

– Last Updated: Aug-04-10 10:57 PM EST –

...... you "have to" use the proper spray gun with the proper tips , you "have to" properly thin the gelcoat , you "have to" have the proper air pressure .

The application of the gelcoat is much like spray painting when the equiptment is correct . It should be applied in 4 layers , the first two are laminating gel , the 3rd is finish gel , the 4th is finish gel .

If the proper technique and equiptment are not used , you will not have a smooth surface during each build up layer and you are screwed .

The only sanding that should be done is on the 3 layer and it should only need to be light sanding , then an extra thin coat for the 4th layer , then course compound , then buffing compound .

The prep work is the prep work , it's the same for the paint or the gel as to what you are trying to achieve with the prep , but you have various opts. to achieve the faired prep result . One of them is a high build primer . Your finish product will look only as good as your prep work in smoothness and fairness .

For a kayak or canoe you will be just as pleased with a two part urethane or epoxy paint system ... "do not spray" these two part systems on (dangerous for you) , but they can be rolled on and tipped off by hand and will self level extremely well .

If using the paint system , clean the hull with gelcoat cleaner , acetone it after that , sand it , acetone it again , fill as required , sand fair , apply high build primer , sand again ... paint the hull .

Basically gelcoat is not paint. It was never intended to be used as an exterior coating. It also isn’t user friendly.

Bill H.

the way it is looking now
is that a good marine paint might be the way to go.

AWLGRIP- forget the rest.

Great advice
I agree that completely re-doing the gelcoat on a boat is not a DIY job and I wouldn’t do it myself. If you want a nice finish on an old boat, the high-build primer and paint method is the way to go.

What you’re thinking of is “PVA”…
…or “polyvinyl alcohol”, which despite the sound of it’s name, is a wax compound.

please clarify “filler” and I need names
OK! OK! I am convinced that painting is the right way to go.

This (latest) post is the first time I have seen the expression “high-build primer” so I would like some clarity.

I googled “high build primer” so I understand what it is. (It sounds logical anyway.)

Can someone indicate a particular brand AND where I can get it?

Does high fill primer actually “self level” or in some way fill in the dimples (where the surface looks threadbare)?

Also (while I’m on the topic of filling) what guidance for filling gouges can anyone provide? I have a kevlar DY Special that is about 30 years old. Some of the gouges are rough. I have read about problems with kevlar “fuzzing” up. I’m wondering about how to prepare the gouges and how then to fill them. Should I sand inside of a gouge or not? Should I fill with bondo or fill with vinylester or not? Will high fill primer “fill in” the gouges?

I read about using the same brand for high fill primer and finish paint. Can anyone recommend brand names and purchase locations?

Thanks to all for your help.


If you are into the fabric you might
want to consider the west system products. A 105 resin and 207 hardener mixed with their fluff sylica could provide a filler that could be laid in place with a small plastic trowel or credit card sized piece of flexible material. Wait for it to kick a little or it will just flow out if the surface is not horizontal. There are also epoxy primers that can be mixed and painted on. The high density sanding primers available at auto paint suppliers are probably not going to fill or properly bond to what you are talking about and that is why I am guessing you might want to go straight to an epoxy filler. I suggest West System products. Good luck. Bill

use a Vinylester filler …

– Last Updated: Aug-06-10 2:01 AM EST –

..... 3M Premium Marine Filler , it's a light putty consistency (Gal., Qt., Pt. cans - uses blue creme hardner - in a squeeze tube) .

or you could use Duratec products from start to finish of prep work (all Vinylesters) , or other brands .

Finish coat systems vary ... they can be polyesters , vinylesters , acrylic urethanes , poly urethanes , epoxy paints , marine enamals , and more . Most of these can be 1k or 2k paint systems (all in one no mixing required = 1k ... two part mixes = 2k) .

Most all of these products can be applied by roller and brush (you do not want to spray the 2k systems unless you have proffesional equiptment and abilities - very dangerous to breath the spray)- (OK to roll and brush) .

Send an email if you need links , I don't feel like posting them , too long .

There are things like "sealers" that soak in to a sanded surface (these are really a tie/bond coat) , sealers are thin and go on first if you want to use them . Sealers are not sanded after applied ... fillers and primers (base primer or high builds) are applied over sealers .

Fillers (pastey applied with trowels, putty knife , etc.) and primers (applied with roller and brush or spray) get sanded (#120-#180) before next over coat with "whatever" .

Certain primers can acually be the finish coat and sanded to a high sheen if you want that , they can be compounded , buffed and waxed ... these are the polyester and vinylesters , they are very hard , come in clear , grays , blacks , and tint bases (off whites) .

Interlux makes some nice (and expensive) 1k and 2k systems . Interlux has a "below the water line" finish coat for racked and trailered boats that "is not" an anti-fouling paint .

For a kayak or canoe , I don't believe there is any reason to use an anti-fouling bottom paint (unless you want to) . Anti-fouling paints (bottom paints) are used to protect the "below waterline" on power and sail boat hulls . They are either "ablative" (self smoothing as they wear away) , or hard (don't wear away) ... they contain coppers and metals .

You’ll find everything you need here
For repainting but it won’t be cheap !

Interlux “Brightsides” is recommended…
…by several wooden boat kit manufacturers. It’s a 1-part paint that’s easy to apply, durable and reasonably priced. It’s not an anti-fouling paint, which as Pilotwingz stated, is not necessary for kayaks.

All good stuff
I’ll be painting the boat for sure. I had some pretty bad hull damage from running over my bow tie-down and getting it tangled in my wheel. It shoved the Thule saddles through the hull on my QCC. I have repaired the damage using fiberglass and epoxy, have the hull sanded smooth and ready for paint. It’s going to be pretty awesome when I am done.

Charlie - acetone wipe?
“We’ve re-gelled broad swaths of outer gel without wax overlay. Just wipe, and wipe again with acetone.”

Just curious - What does wiping w/acetone do for the job?

What I’ve seen is…
…that although unwaxed gelcoat won’t cure hard on the surface if it’s exposed to air, it does cure underneath. You can wipe off the uncured surface layer with solvent, exposing the cured gelcoat. However, it’s messy and the results are inconsistent, so it’s not something I would recommend.

ok - thanks.