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Old 10-04-2019, 23:53   #1
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Fiberglass repair on keel

Last fall when I hauled out my new-to-me Aloha 34, I discovered a small damaged area on the bottom of the hull. Looking for some advice on how to go about repairing it. I've had very little experience with fiberglass repair previously, only repairing a small hole in the hull of a small runabout using several layers of glass mat with 2 part West system kit. Any comments or advice are welcome.
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Old 11-04-2019, 00:23   #2
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Re: Fiberglass repair on keel

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Originally Posted by sunluvr View Post
Last fall when I hauled out my new-to-me Aloha 34, I discovered a small damaged area on the bottom of the hull. Looking for some advice on how to go about repairing it. I've had very little experience with fiberglass repair previously, only repairing a small hole in the hull of a small runabout using several layers of glass mat with 2 part West system kit. Any comments or advice are welcome.
Hi, might I suggest searching for posts by a member here, Minnaret I think is the name, a wealth of the information you are seeking.
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Old 11-04-2019, 00:41   #3
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Re: Fiberglass repair on keel

You will need to build that area back up. So you will want to use some thickened epoxy. Thicken it up with cabosil and build it up to the general shape you need. You may need to do this more slowly, a few steps at a time, to prevent exotherm.

After you have the general shape, grind in a "dishpan" taper around the edges of the repair to create a taper all the way around the repair where it meets the existing glass.

Also grind down your shaping/filling area just enough to allow the layers of glass you put on there to be flush/fair with the existing lines of the keel.

Use a thin glass to get around the tight curve/radius of the shape of the keel. Just a 6oz cloth, but many layers of it should do the trick.

After you've glassed in the repair, grind it all flush/fair and you're done.
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Old 11-04-2019, 04:07   #4
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Re: Fiberglass repair on keel

If you’re looking to get better at DIY fibreglass repairs, suggest you check out Boatworks Today YouTube channel. He’s also on Patreon and will do personal consultations over video on projects like these for those who support his channel via Patreon. I’ve learned a lot watching his videos... good luck with the repair!
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Old 11-04-2019, 04:36   #5
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Re: Fiberglass repair on keel

Easy fix and not.structural.
Grind the arrea and clean it nicely
Add few layers of glass using polyester (make sure to allow space )
Add thickened polyester with cabosil fumed silica.
Hand grind (very easy with silica ) and shape it .
Prime it

Paint it

Go back.in the water .




If you can't find silica.you can use fiberglass and then on the space add just resin it will be easier to grind (silica is better option and nicer.finisj )
Epoxy is.too expensive and there is not point of using it there
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Old 11-04-2019, 08:41   #6
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Re: Fiberglass repair on keel

I second boatworks today you tube channel...that guy is good. Id look into using vinyal ester resin as its better if there is any moisture in the existing glass. Grind the chunk back...I think its 12 to 1..so if its a inch deep , grind out 12 inches around it...but check on that ratio(west system has some great videos and books on fiberglass repair). Then make a bunch of fiberglass patches, put the largest one down first that will cover the whole ground area, slowly moving to smaller and smaller till the void is filed..if it is gouged past the glass into the core of the keel, then you can fill the core portion with filler..then do the glass patch like I wrote above. Watch your compatibility...you can put epoxy over polyester but not the other way around..so don't use a epoxy filler then cover it in polyester. Youll have to check about the vinyl ester. Thoery is use the viynalester because of the moisture..Ive always just used epoxy for everything possible because I like it the best...I hate using polyester. DO NOT just slather a bunch of filler in there...it needs to be patched with glass.
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Old 11-04-2019, 12:37   #7
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Re: Fiberglass repair on keel

vinyal ester
vinyl ester
viynalester

Are all these the same stuff?

Or is there a product trademark in there?
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Old 11-04-2019, 12:55   #8
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Re: Fiberglass repair on keel

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Originally Posted by john61ct View Post
vinyal ester
vinyl ester
viynalester

Are all these the same stuff?

Or is there a product trademark in there?
HA! I figured one of them was right. But I build and fix boats, If I learned to spell or type ,Id have to charge more.
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Old 11-04-2019, 18:59   #9
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Re: Fiberglass repair on keel

Nice thing about fiberglass repairs.....if you don't like what you end up with just grind it out and start over. Have fun.
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Old 14-04-2019, 12:26   #10
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Re: Fiberglass repair on keel

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Originally Posted by TheLastPirate View Post
I second boatworks today you tube channel...that guy is good. Id look into using vinyal ester resin as its better if there is any moisture in the existing glass. Grind the chunk back...I think its 12 to 1..so if its a inch deep , grind out 12 inches around it...but check on that ratio(west system has some great videos and books on fiberglass repair). Then make a bunch of fiberglass patches, put the largest one down first that will cover the whole ground area, slowly moving to smaller and smaller till the void is filed..if it is gouged past the glass into the core of the keel, then you can fill the core portion with filler..then do the glass patch like I wrote above. Watch your compatibility...you can put epoxy over polyester but not the other way around..so don't use a epoxy filler then cover it in polyester. Youll have to check about the vinyl ester. Thoery is use the viynalester because of the moisture..Ive always just used epoxy for everything possible because I like it the best...I hate using polyester. DO NOT just slather a bunch of filler in there...it needs to be patched with glass.
not to doubt your experience but I remember reading one of minarets posts suggesting the smallest patches should go in first and the largest, last. reason being that if the large patch goes in first and fails the entire repair fails with it. if the smallest go in first and each successive layer goes over the last layer, they all have to fail for the repair to fail completely which is much less likely to occur.
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Old 14-04-2019, 12:31   #11
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Re: Fiberglass repair on keel

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not to doubt your experience but I remember reading one of minarets posts suggesting the smallest patches should go in first and the largest, last. reason being that if the large patch goes in first and fails the entire repair fails with it. if the smallest go in first and each successive layer goes over the last layer, they all have to fail for the repair to fail completely which is much less likely to occur.
This is accurate
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Old 14-04-2019, 14:13   #12
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Fiberglass repair on keel

My memory might be wrong but I seem to recall the largest goes first.
You’re making a structural bond not simply fairing it smooth.
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Old 14-04-2019, 17:32   #13
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Re: Fiberglass repair on keel

I had to do a similar repair, except that mine was in front of the keel.
In a nutshell:
  • Grind the area until you get to good lamination - like "green" glass. Water has gone into the bare glass and penetrated the lamination. If you cover what you see you may have problems later. Grind away until you are out of the "white" and you are sure the glass lamination is good.
  • Build up the area with glass - use biaxal without the mat. Do not use anything other than epoxy - the bond is much superior. Build it up in several layers, if it is too deep you may have to laminate over several days to avoid too much heat build up and air bubles.
  • Between layers, wash to remove the amine blush and sand or use peel ply.
  • When you are very close to the sorrounding suface you may use epoxy fairing compound to make it even and pretty.
  • Then barrier coat and anti-fouling.
It is not rocket science but do your reaseacrch and good luck with the project.
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Old 14-04-2019, 18:08   #14
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Re: Fiberglass repair on keel

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Originally Posted by er9 View Post
not to doubt your experience but I remember reading one of minarets posts suggesting the smallest patches should go in first and the largest, last. reason being that if the large patch goes in first and fails the entire repair fails with it. if the smallest go in first and each successive layer goes over the last layer, they all have to fail for the repair to fail completely which is much less likely to occur.
This is my understanding as well.
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Old 14-04-2019, 18:33   #15
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Re: Fiberglass repair on keel

We have glassed in a few unneeded thru hulls, and patched up our keel as well. We used west systems, they were also available to call so as to clarify any questions we had while doing the work. We laid in the class widest to smallest, worked fine, and that was three plus years ago. Take your time, do it right, step by step. This was our first time doing fiberglass work and all was went well.

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