Fiberglass repair (Howmar DC)

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Fiberglass repair (Howmar DC)

Postby Tomsoyer » Tue Mar 27, 2018 12:29 am

Hello,


I have a small sailboat that I am trying to repair. Its a Howmar designers choice(http://sailboatdata.com/viewrecord.asp?class_id=4096). First thing I would like to fix is some fiberglass cracking and what i think is delamination near the mainsheet rigging. I have read up on fiberglass repair but I have not actually done any so i am looking for any advice.


Where do i start? I believe i am going to need to grind around the cracking and delamination. Home much material do i need to remove? Is there anything i need to be concerned about because of its location?
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Tomsoyer
 
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Re: Fiberglass repair (Howmar DC)

Postby GreenLake » Tue Mar 27, 2018 3:25 am

Tom, this forum is focused on a particular type of boat, the O'Day DaySailer, and all its models. That said, we don't usually kick out anyone just because they have the "wrong" type of boat - however, as long as it doesn't distract from the focus of the forum.

Your question is fairly generic and the answer applicable to any kind of fiberglass repair.

For sources of information: if you spend some time reading the older posts here on the forum you will find similar projects discussed and might come away with something useful for your project. You can even go back ten years and the advice would not be out of date.

That said, there are (at least) two manufacturers of epoxy (the go-to material for making these repairs) that have published booklets on how to effect a repair. They are West System and System Three. Locating them on the respective websites, downloading them and reading through them should be your first step.

I don't know this type of boat (see opening statement above) but if that crack flexes when you put load on it, you have damage that goes deep and you will have to remove enough of the white gelcoat so you can see where the laminate is milky (broken) or clear/dark (good).

After you've done your assigned reading, you will know how far from the edge of the good part the repair will have to extend.

This will most likely mean removing the fitting - which may be bolted into a backing plate that's drilled and tapped. That would complicate things.

If optics aren't your main concern, it may be easier to apply a patch on the outside and then use longer bolts, if necessary to reach the same backing plate. Be generous in the dimension of the patch, extending it 2-3" down the sides and also fore and left and right of the cracked area. (Remove gelcoat for better bond).

Put a few layers of laminate, each a bit smaller, so you get a "stepped" and not an abrupt transition.

Paint when done for UV protection and replace the fitting. (Waxed bolts left in place during the repair will prevent the holes from filling).

Trying to make an invisible repair might be that much more challenging and unless you are trying to restore an old boat to pristine condition I might question the need.

Good luck.
~ green ~ lake ~ ~
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Re: Fiberglass repair (Howmar DC)

Postby Tomsoyer » Wed Mar 28, 2018 12:29 am

Thanks for the response.

I have read someg books on fiberglass repair. Just trying to get some advice on how involved my repairs might be. I am a little nervous about grinding away the fiberglass.

You bring up a good point about the backing plate. I am concerned if I snap the screws of when trying to remove them in will have an issue. There is no access that I can see to the backing plate.

Thanks
Tomsoyer
 
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Re: Fiberglass repair (Howmar DC)

Postby GreenLake » Thu Mar 29, 2018 1:00 am

If you apply a "patch" then you don't need to remove the damaged fiberglass, but for a good bond you''ll want to clear away the gel coat. At that point, you will also be able to see how far the damage extends (milky laminate). A patch would preferably have a bit of a transition in thickness so there's not a thick edge that creates a "hard spot. (Not sure with the geometry that you have whether that's something you need to worry about too much).

If you do use a patch, you can cut out the backing plate and just glue a new one to the underside of the patch - so to speak. It takes a bit of ingenuity, but nothing prevents you, for example, from laying up what amounts to a bit of pre-fabricated fiberglass U-channel and effecting the repair with it (by gluing it on) rather than doing the lay-up in place. There are many different options with different trade-offs.

If you use WD-40 or the like and go about it carefully, the screws either come out or they don't, no need to snap them off. (Use an impact driver?).

If you can figure a repair with a pre-fabricated part that adds its own backing plate, then you gain the ability to substitute newer hardware (which likely has a different bolt pattern).

Good luck!
~ green ~ lake ~ ~
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