coaming repair

I noticed that I have a crack along a portion of the coaming on a fiberglass boat, and there is a bit of “play” in that area.

I did a search and see people mention G-flex as a repair, all of which i assume is done on the inside of the boat.

When I look under the coaming lip on the outside of the boat I see a rubber band looking material which goes all around, though pinched a bit where the crack is.

I’m wondering…

Is that a gasket? or a type of rubber tape.

Does it need to be removed before the repair is made ?

Thanks for any advice…I’m up here in NH if anyone knows someone who could fix it up ( though I know it’s the busy season.

I leave for a 2 week kayak tip in mid August so it would be nice to have it all squared away by then.

(I’m willing to try the repair myself if it’s pretty straight forward and don’t need to be a rocket scientist to figure it out.)

You may get it done with just G-flex.
I mended a crack in a rim (coaming) I laid up myself, using a urethane glue.

But if your crack is of any extent, if it goes around the base where the coaming meets the deck, then you may want to include a slip of glasscloth or Kevlar to back up the fix.

That black tape is to provide a smooth, non-abrasive seat for the rand of the sprayskirt. You may not need to remove it if you can give the boat enough time that you are SURE that there is no water lurking under the tape and sitting in the break. That water would impede entry of epoxy into the crack, and might cause non-optimum bonding.

Ideally the crack might be opened up to a V-form from inside. You may have to improvise a tool. The FG around the crack needs to be cleaned and sanded.

G-flex may need to be warmed a bit to soak readily through the glass or Kevlar. Once you get the cloth wet, maybe you can get some plastic food wrap film over it for a smooth result.

I’d invert the kayak, sand the underside of the rim and lay up a couple layers of glass on that with epoxy. There’s alot of forces on the coaming, the odds of just gluing it back together and having it hold up are poor. There is a reason it cracked to start with, have to fix that first.

Bill H.

You could use G-flex if you have it, but on a fiberglass boat regular epoxy will work fine. The coaming can take a lot of stress. I would recommend using cloth (fiberglass and/or Kevlar) as well. Applying the glass on the inside of the cockpit coaming should not effect the skirt fit.

it’s a crack so use fiberglass cloth …

– Last Updated: Jul-18-10 9:43 PM EST –

..... to span the crack (9 oz.)... both sides is better than one side , but inside is better than no sides . Try to cover about 1-1/2" beyond crack on all sides as a min.

Prep. - rough up (sand paper #60) and sterilize (acetone) the area around the crack real good (remove the gasket if you can) . Scratch out a small V in the crack .

Mix a little (1 oz.) of resin (epoxy or polyester) , dip the cloth patch into the resin mix to wet it , use a disposable brush to wet the repair area around the crack where the cloth patch will go ... put the wetted cloth patch over the crack (repair area) ... put a piece of wax paper over the cloth patch repair area ... using fingers (disosable gloves) , putty knife , small piece of wood , etc. with light pressure rub over the "wax paper" above patch area to set cloth and resin (work out air and make flat) ... remove wax paper and clean off (acetone and rag) squeezed out resin from area around (beyond) the desired patch area (clean excess resin off , almost to cloth perimeter while still wet - acetone and rag) .

Set (laminate) another cloth patch over the same one for extra strenth if desired ... do this the same way , do it imediately after excess resin has been cleaned up while resin is still not fully cured .

Do this to both sides is best ... sand to smooth and fair after resin has hardened ... fair out more with a vinyl ester filler if desired (3m Premium filler or similar) ... gelcoat over if desired (just paint gelcoat (finish gelcoat) on with brush (to desired thickness) and sand to fair after hardened ... keep reducing sand paper weight to 600 if you want a semi glossy finish) .

If you have intention of using the vinyl ester fairing filler and gelcoat , then use the polyester resin "not epoxy" .

West epoxies will stick well to gelcoats
and vinylester and polyester. They won’t work with glass mat, because it has a coating that it incompatible. Otherwise, epoxy can be considered a universal repair material for composite boats.

only thing is g2d …

– Last Updated: Jul-18-10 12:25 PM EST –

...... polyester and vinyl ester products (polyester gelcoats , vinyl ester fillers) don't make a good and permenant adhesion to epoxy ... they do make an excellent and permenant adhesion to poly ester resins .

Although they will appear to stick on epoxy , they run the very real chance of delaming in future .

Epoxy sticks well to poly and vinyl esters , but not the other way around . So if one wants to gelcoat or use vinyl ester fairing fillers , best to use the poly and vinyl ester resin products for build up , laminating , ect. ... if paint is to be final finish , epoxy OK ...

If you have an epoxy repaired area that you wish to gelcoat , you should use a primer coat over the epoxy first , such as Durathec Polyester Surfacing Primer ...

epoxy and mat
Actually epoxy works ok, not great but ok with glass mat, the styrene that holds the fibers together just breaks down more more slowly in epoxy than it does with one of the esters. It’s a trick using epoxy with mat in warm weather, it’s a race between the setting time of the epoxy and the styrene breaking down, sometimes the styrene wins ;(

There’s just little reason to use mat unless you have no choice.

Bill H.


– Last Updated: Jul-19-10 7:04 AM EST –

plan on making the repair today . Think I have the gist of it.

glass glass material ie. fiberglass cloth
ester is..?

I don't need to gel coat it as I will make the repair on the inside.

epoxy is ok
g flex is also ok
resins are ...?

I don't want to over think it so I will blunder along as best I can. I'm sure it will all make sense when I am done.

Thanks again for all the advice, it's much appreciated

Sand the area
You have to sand the surfaces for good adhesion. Use epoxy.

so how did it all work out for you ??
… you know , if you don’t like the way it turned out the first time … you can always just sand it off again (remove everything you just applied) with a random orbit sander , and do it again . That’s one of the beauties of small area repairs for first timers , real easy to remove what you just did if you don’t like it .

Nice to know it wouldn’t be a disaster,
but, my supplier, says specifically that glass mat and epoxy are incompatible.

Yes, though we’ve gotten off subject.
I never saw a coaming repair where gelcoat was involved. And if one is serious about bulletproof repairs, one should use epoxy and forget about gelcoat afterward. Gelcoat is just an inferior material.