Fiberglass and gelcoat repair

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isubarui
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Fiberglass and gelcoat repair

Post by isubarui »

I finally hit something hard enough to put a crack or at least knock off a good chunk of gel coat on my kayak. It either happened when I ran into a stump submerged under water which I think might have had something nailed onto the top of it or from kayaking over vines hanging from trees while making my back into the back of a little river. Anyway you can see the damage. I do not think that the damage is very structural although there are some fiberglass fibers that are a little frayed and cracked up. There was no water in my kayak though so the crack must not have gone all the way through.

What is the best method for me to repair this crack?

I know very little about fiberglass besides there is fiberglass mat and fiberglass weave. There are also different types of resins with one being epoxy and the other being polyester. From what I understand the polyester is the most popular and is most likely what my kayak(Kaskazi Dorado) is made from.

There are a few different methods from what I understand in the way of repair.

Method 1 requires removing all the injured area through the kayak and then filling it back in with alternating pieces of mat and weave that slowly get larger. Kind of like an upside down pyramid effect. This method would require me having great access from the back side which I am not so sure I have. Gel coat is then applied first or can be applied at the end of this procedure.

Method 2 would require removing down the damaged area by sanding and then just laying a piece of fiberglass mat or maybe only the weave over the damaged area from the bottom of the kayak. Letting it dry and then applying new gel coat and sanding until smooth.

Secret method 3????

Maybe I know more about fiberglass than I thought but I could still use some direction and input on how to tackle this problem. There is a deadline of Oct. 31 around 2-3am.

Here are some pictures so you get a better idea of what I am working with. The other oyster rash and scars will need to be dealt with at a later date.

Image

Image

Image
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Night Wing
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Re: Fiberglass and gelcoat repair

Post by Night Wing »

Take it to a place that specializes in gelcoat repair like a boat dealership. It'll cost you, but if you don't really know what you're doing, the odds are you'll be taking it to a boat dealership for a second go around repair job. It's the best money you'll spend on your fiberglass yak.
Last edited by Night Wing on Thu Oct 22, 2009 9:58 pm, edited 1 time in total.
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Re: Fiberglass and gelcoat repair

Post by kfsrmn »

The following link explains it all. Not my work. http://community.webshots.com/user/brian_nystrom-reg" onclick="window.open(this.href);return false;
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Re: Fiberglass and gelcoat repair

Post by barditch »

8) Those are high dollar yaks...I'd go find me a dealer! You want it done right! JMHO!
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Re: Fiberglass and gelcoat repair

Post by isubarui »

I will be doing it myself. I do not think it is outside my abilities. I really doubt that this will be the last time I run into something that puts a hurt on my kayak. I need to learn how to do it on my own.

Unless anyone has any suggestions I will be trying it tomorrow with an external patch and then an exterior patch. Sand them down and them cover with gel coat.
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Re: Fiberglass and gelcoat repair

Post by TDD »

It's not that bad to need that kind of repair from what I can see in the pictures ..... looks like the gel coat is really the only thing that is damaged. You have a timeline and again ..... it doesn't look that bad in reality.
If it was mine I would go over to West Marine or whoever and either buy the Mas Gel coat Repair Kit in white for $27 or even white Marine-tex for $17 and simply fill in all of the damaged gel coat including the deep shell gouges. First I would make sure that it is very clean, break out the small loose ends of the damaged gel coat and use some 80 grit sandpaper along the edges and along the deep gouges then douse and clean the whole area to be repaired with some 91% alcohol (151 won't do) then fill the damaged area with the gel coat repair or Marine-tex using a small spatula. keep a small bowl of alcohol near by to clean up and smooth out any messy area. Let it dry at least over night but another day would be even better. Do a light wet sand with some 120 wet paper just to cherry it out then wax the whole yak and stand back and be happy that it was only a very minor repair. Save all that fiberglass structural repair for when it flys off the truck and lands on the pavement.
I remember when you first bought that Dorado .. we fished together one night off of 103rd I think .... I remember that I couldn't keep up with you in that rocket.
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Re: Fiberglass and gelcoat repair

Post by preacher »

My experience in these situations goes along with TD's idea. I've fixed a lot of damaged spots like this in bass boats with Marine Tex and never had a problem.
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Re: Fiberglass and gelcoat repair

Post by gerald »

Ok...if you have no damage or cracks to the inside of the boat then all you'll have to worry about is the stuff on the outside. To me it looks like you've damaged more than just the gel coat. Still no problem. Sand out the damaged area until you have integrity, or in other words--nothing loose at all. Gently feather the area but still leave a visible hump at the edges of the depressed area where you go back to undamaged surface. You'll want to apply a couple pieces of cloth inside that depressed areas--how ever many it takes to start building up the hole so it is fairly level with the undamaged surface. These few pieces may start out smaller and get slightly larger--that's ok at this point. I would probably do one or two at a time and sand the humps and edges down each time. Up to this point you are just filing the hole and helping regain strength. Before the next step you may use goopie or some filler to do a final fair and smooth on the patch area, but I probably wouldn't because I'd have already made it fair as I worked on it.

Now you have a hole that has been filled and brought fairly level with the undamaged surface but you aren't overlapping much. The final step is to put one large piece over the patch--overlapping at least 2", preferably a little more--and then a second smaller piece over that. This is important. The top piece must be smaller than the bottom piece in order to maintain structural strength. these can also be done one at a time or at the same time. Sand and feather smooth. Depending on the type of resin you are using you may have to paint the patch or add color to the final coating.

I don't know what resin your boat is made with. Could be polyester, could be vinylester, probably not epoxy, may be something else. Do some research and find out what it's made with. Use a compatible resin.

This is an easy, permanent repair when done well probably stronger than the original boat.
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Re: Fiberglass and gelcoat repair

Post by isubarui »

Ok now the plot thickens.

I removed the cracked area and this is what I found. I am guessing that this is a problem from the factory. There seems to be a large amount of bubbles/air pockets in the fiberglass that should not be there. The brown coloration is obviously a problem as well.

Now I guess the logical thing to do would be remove the whole area and then build it back up but there is a fish box in my way. I could just cut a hole in the fish box(where the blue circle is on the pictures) and access it or I need to do it all from the bottom of the kayak. After the repair is over I could either replace the hole in the fish box with a sheet of fiberglass or come up with some type of cover that could be removed in the future. I have always hated the fact that the fish box covers up so much of the front portion of the kayak. I guess I could put some type of hatch in place of the bottom of the fish box so that I would always have access to it in the future.

My pictures of the fish box area from above are not that great so here is the link to the manufacturers website.
http://www.kaskazi.co.za/kayaks/kaskazi_dorado.shtml" onclick="window.open(this.href);return false;

Pictures

Normal wear that needs to be covered back up.
Image

The cracked area removed
Image

Close up
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From the top with the blue circle
Image

I will contact the manufacturer of course but the last time I had a question about the kayak it took them two months to respond. I could always call south africa as well I guess. :(
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Re: Fiberglass and gelcoat repair

Post by gerald »

You can probably forget the bubbles. Not suppose to be there and it's poor quality control but that's just the way it is sometimes. I would sand it out more until I was back to good surfaces then follow the procedure I earlier outlined. I would not recommend cutting through the hull unless you see damage and cracks on the inside. The color variation is just something you'll have to figure out how to work around.

Of course...this is all just my opinion--and it's hard to diagnose from a distance....
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Re: Fiberglass and gelcoat repair

Post by isubarui »

Gerald, from what I understand you are basically outlining the steps similar to what is portrayed here?

http://outdoors.webshots.com/album/185236435CtCzwx" onclick="window.open(this.href);return false;

I will sand out the area and see how far down the damage and the air bubbles go. I will post some pictures to make sure I am not working with something more serious. I will probably go ahead and get some mat, resin, and gel coat. I am fairly certain that the kayak is made from a poly resin.
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Re: Fiberglass and gelcoat repair

Post by TexaRican »

isubarui wrote:I could always call south africa as well I guess. :(
Get a skype account. I call all over the world almost daily and it is dirt cheap.
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Re: Fiberglass and gelcoat repair

Post by TDD »

I still think that you may over do it .... this is not a 70mph speed boat hull and from what I can see you still only damaged the gel coat but there are air bubbles in the glass in the area which is why a scrape ended up taking gel coat with it .... time line ....... a low viscosity self leveling epoxy in a syringe to fill in the bubble voids .. let it dry then the gel coat or Marine Tex and go fishing ........... if you have a problem later you can always sand it all out and do a major rebuild later. You are better doing that than getting in a hurry to meet a time line in my openion.
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Re: Fiberglass and gelcoat repair

Post by gerald »

isubarui wrote: http://outdoors.webshots.com/album/185236435CtCzwx" onclick="window.open(this.href);return false;
Ah yes...very close to what I outlined. Maybe the biggest difference is in the last two layers of my process being large then smaller to avoid cutting the largest piece when sanding and feathering.

You might also listen to TD. He has some experience with this kind of repair that has worked well.
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Re: Fiberglass and gelcoat repair

Post by isubarui »

TD wrote:I still think that you may over do it .... this is not a 70mph speed boat hull and from what I can see you still only damaged the gel coat but there are air bubbles in the glass in the area which is why a scrape ended up taking gel coat with it .... time line ....... a low viscosity self leveling epoxy in a syringe to fill in the bubble voids .. let it dry then the gel coat or Marine Tex and go fishing ........... if you have a problem later you can always sand it all out and do a major rebuild later. You are better doing that than getting in a hurry to meet a time line in my openion.
Well the thing you cannot see from the pictures is when you press on the middle of the crack there is a significant softness that you can feel. There is almost no hardness left to this area it feels like. It really leaves me wondering what this kayak is made out of and what they did at the factory. Maybe this kayak was a foam fiberglass prototype they were experimenting with. I do not know about the process of using foam and fiberglass but it is really soft like there is some type of foam in there. The other areas I have drilled on the kayak is solid fiberglass but of course the hull was made differently than the top of the kayak where all of the holes were put. I will just sand off the black fiberglass and see what is under there but I keep getting the feeling that I will be cutting a hole in the top of the kayak through the fish box. That is just how soft the area is when I press on it with my finger.

Does anyone know anything about foam and fiberglass construction?
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Re: Fiberglass and gelcoat repair

Post by gerald »

Foam and fiberglass construction is very common in boats, paddles, etc.. This is foam cored construction. Wood composite boats are nothing more than wood cored construction. Same process, just different cores.
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Re: Fiberglass and gelcoat repair

Post by TDD »

And you are definitely correct in that just looking at a pic does not tell the whole story ..... without putting my hands on it anything that I say is purely speculation. I think that my main reasoning has been that if the structural integrity of the fiberglass is intact then it mainly needs to be sealed off with the gel coat repair and you can always come back and get radical later if you find that was not good enough.
I just finished repairing an 8" crack on the bottom of my thermo-mold Trileen Phoenix 140 that was next to the scupper right in front of the seat where there was no way to get to it without installing a small hatch in the floor ..... I did and it worked out very well for me. I will try to post a thread this weekend about the repair but it really won't help you much since you are working with a very different material. I did do a lot of fiberglass auto and boat repair years ago but there is some really good new epoxy's now that are flexible and work a lot better on light more flexible structured kayaks etc.

Ok ..... I am gonna throw this out to you for consideration.
Go to WestMarine and buy the West System 650-k ... G-flex epoxy repair kit for around $27
Duck tape off the bottom where the damaged glass is and open the fish box and drill a 1/2" hole right above where the damage is ... if you can see a void area between the deck and hull and it is not filled with foam .... level the yak, right side up, and mix up the full batch of the G-flex epoxy which is around a full pint and pour the full amount straight down the hole (maybe you should mix half first then if it takes it all mix up the other half and pour it in) ....... this stuff is a nice low viscosity and will fill in all of the voids in the glass and will definitely strengthen the whole area ..... it will puddle out right there where it is needed. Give it at least 24 hrs to cure 48 would be better then Marine-tex or gel coat repair the bottom as normal.
If you would like to kick any of this around give me a call ... Tim Darby 409-789-2035

The main thing about foam core is the fiberglass is probably a lot thinner .... the foam is the structure and the glass is there to stiffen and strengthen and the gel coat to seal, smooth and pretty it up. It is a lighter hull .. period.

Link to the crack repair on my Phoenix 140 .... http://www.texaskayakfisherman.com/foru ... 1&t=131962" onclick="window.open(this.href);return false;
Last edited by TDD on Sat Oct 24, 2009 6:10 am, edited 1 time in total.
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Re: Fiberglass and gelcoat repair

Post by TDD »

another thing ... if it is a foam core and there are voids in the glass skin then the skin has probably seperated from the foam also which would feel mushy so you will need to rebond the glass skin to the foam. The G-flex epoxy would also work great for that and would fill in the glass voids to boot .... that stuff is strong and flexable which will be of major importance in your hull.

Image
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Re: Fiberglass and gelcoat repair

Post by isubarui »

I removed the brown fiberglass, which wasn't very hard as it just flaked away, and underneath it I found what I assume is "foam" matting.

Image

The majority of the material seems to be stable except where the blue circle is. This is an area that seems to have the brown fiberglass underneath it. I was all ready with my fiberglass and poly resin to lay down a new layer and then gel coat it but now I am not so sure. Since this is a foam filled kayak hull(I think) there is a possibility from reading the kaskazi website that this is an epoxy fiberglass setup with a foam core. If this is true will my poly resin bond to the epoxy fiber glass or do I need to go find some epoxy resin?

I will probably be using the G-flex now which means I need to make another trip to west marine.

TD, I will probably be giving you a call in a little while.
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Re: Fiberglass and gelcoat repair

Post by bowgarguide »

Poly resins melt most foams,plus will not bond to some things,epoxy will bond to just about anything and shouldnt melt the foam.
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Re: Fiberglass and gelcoat repair

Post by isubarui »

Well I got it all back together, I think. I sanded down the area some more and then laid fiberglass and epoxy down over the entire area. I probably could have gotten a lot more fiberglass mat in there if I squeezed the epoxy out with a spatula or whatever that tool would be called but it all worked out fine with this being my first fiberglass project.

Fiberglass laid down and then sanded.
Image

Taped off.
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Gel Coat down.
Image

Refinished the stern.
Image

The white on the gel coat I used was a little different color white than the original gel coat so it shows up on the kayak but that should only be a cosmetic problem. The fiberglass layer was a little thick and shows through just under the gel coat but I will just leave it the way it is for now. The repair seemed very strong and should hold up for a long time. I took the boat out for a paddle after everything was done and it worked perfectly so there is nothing to complain about I guess. I would like to thank everyone that gave me advice.

The bottom sanded.
Image
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Re: Fiberglass and gelcoat repair

Post by TDD »

:clap: :clap: .... very good .. white can be almost impossible to match perfect but is a great color to almost match and for the bottom it's perfect. I say it came out great.
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Re: Fiberglass and gelcoat repair

Post by gerald »

Looks good to me as well.
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