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backing support for Fiberglass Repair

I have a large hole with almost no access to the back. I am thinking of laying up a piece of thin glass for a backer but I am not sure if it will conform to the countour of the boat. Please see picture. Let me know if you have any ideas. BTW, the hole was great for putting in some new supports/floation but I think it is going to a challenge to fill.

Thanks in Advance,

BrainCorrel
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AN400
 

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DanB

Crabber
In short you will work through the deck to fix the hull since it will need the structure of some internal lay-up. You want to lay in fabric a good 6" to 8" wider than the hole and several layers thick to tie the hull structure back together across the gap. You are not just fixing a hole here you are reinforcing the working area of your hull.

After that's complete work at the outside bridging the successive setbacks you have sanded out with fabric and resin thickened slightly with milled fibers. Top off the last 1/32” with marine-tex white for a cosmetic finish. You are working with epoxy laminating resin, right? If its polyester resin, top with gelcoat.

For the deck - make a patch 6" larger than the hole and a couple of layers or more thick. Only wet out a center area just smaller than the hole. When that's set up flip the boat upside down. Working from underneath reach in and paint a 6" area around the hole with resin. Wet out the boarder of your inner patch. Push it inside and let it settle onto the resin you painted inside. Put a screw in the center of the patch if you want something to hold it with for positioning. Let the inner patch set up. Proceed with the outside finishing patch tying together the concentric setback layers same as you did for the bottom.

This is only a simple overview incomplete in many ways. Get a good book or two for the details - like the fillers you may want to use. ;)

Fiberglass Repair: Polyester And Epoxy by David Aiken and Zora Aiken

The Fiberglass Boat Repair Manual by Allan H. Viatses

There are some WEST System videos on YouTube you might find helpful.
 
Thanks for your input. Hole on the right is for an access port. I am using epoxy and I have watched the videos on YouTube.

My main question is how to build a support for the first layer ie. plastic sheeting foam and then something on the outside. Since the surface is not flat I need to put something flexible. I am just not sure how to support it and what will conform nicely.
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EL250E
 

DanB

Crabber
One simple approach would be to cut out a piece of corrugated cardboard box to snuggly fit the hole. Shape it for the keel contour. Cover the cardboard side that will face inward with heavy waxed paper or 2 mil plastic sheet – drop cloth stuff. Tack the waxed paper or plastic to the cardboard with rubber cement or anything that will make it follow your shaping tightly. If you use plastic, spray it with PVA. Tape the cardboard cut out in the hole. Reach through your access port and feel that the cardboard plug is flush with the inner surface. You are now good to start placing the internal reinforcement layers. Just remember when you squeegee over the plug area not to press so hard and push it out.
 

Petrel

Member
Thanks for your input. Hole on the right is for an access port. I am using epoxy and I have watched the videos on YouTube.

My main question is how to build a support for the first layer ie. plastic sheeting foam and then something on the outside. Since the surface is not flat I need to put something flexible. I am just not sure how to support it and what will conform nicely.
Geez, Braincorral! You know how to make a waterlogged, multi-crappypatched, soggy Sunfish owner feel sooooo good :D

I've yet to do my own, so listen to the folks here. I will just offer a bit of what a fiberglass small sailboat manufacturer/repair fellow told me (when I asked about how to repair a "crack" that went THROUGH the hull to the cockpit floor of a molded polyester resin (maybe some fg fabric in the matrix, but largly resin-shell hull sailing dinghy/racer: He mentioned using backing material. What he suggested (BUT** this was for a repair to the hull, not the KEEL/Keelson (which it looks like your boat needs as well as a hull repair))

He said that he puts the fiberglass cloth onto a piece of cardboard and wets it thoroughly there. BACKUP a bit. Before wetting it (with his preferred West System marine epoxy) he said:
1. Widen the crack, hole (which you've done.
2. CLEAN it -- ocean side and as best you can, the interior side.
3. Be sure to make the fiberglass cloth (as Mike just suggested) wider than the open/crack area. Cut it and fit it DRY before you set about using resin to bond the patch. Note: on the exterior, because you have more space/accessibility to work, you'd do it more carefully, again, see Mike's reply above -- you graduate/stagger the milled/sanded out area.).
4. FOR the BACKING: But, back to the inside part of repairing a hull hole from TONY: you get a piece of cardboard (part of a carton is fine) and place your fitted dry fiberglass on it.
5. Next, (as I understood him -- don't hold Tony responsible for what I might have misunderstood ;) ), you put strings (some use copper wire), perforating both the cardboard and the cloth. These strings or thin copper wire will be how you will hold --perhaps via a very patient helper, or a jig -- the backing support in place while it sets. ((I understood what he meant because I'd watched an episode of PBS's This Old House where they demonstated how to repair a large section of missing plaster wall (or sheet rock). They used a baloon to hold the plaster repair in place. That is, the *initial* gap filler, notthe finished smooth, flush repair.))
6. After that cures, you can set about reparing the hole from the bottom as Mike suggests. You grind/sand out in a graduated way and clean will something like acetone to prepare. That is, the preparation wound farthest from the center is more shallow.

As for the missing keel (?wood) or keelson section (it appears this is the case ), I'm not sure how to approach this. What I've suggested above doesn't address this, but assumes the keel isn't involved.

I admire you for undertaking what seems to me (NOVICE) like a robust project. I'm sure the folk here will give you good suggestions as Mike already has. Tony didn't tell me specifically how to HOLD the patch in place as it cures, but I immediately thought no problem, I'll borrow some kid off the street ;) .

Keep us posted, please.
 

Porpoise2

New Member
"...My main question is how to build a support for the first layer ie. plastic sheeting foam and then something on the outside. Since the surface is not flat I need to put something flexible. I am just not sure how to support it and what will conform nicely..."
You could use the outside of the hull nearby as a mold.

Lay up two layers of cloth bigger than the hole onto wax paper and let it set. Sand it with coarse sandpaper, then slide it inside, having previously coated it with filler and epoxy. Lay a few strips of wood or aluminum scrap and put sheetmetal screws through them into the previously-cured patch to hold it firmly in place until set. Then lay up enough cloth (or that non-woven fuzzy stuff—mat?) and epoxy to bring it up "proud" of the bottom. Sand to fair the patch, using a thin plywood block for backing.

Easy-peazy. :cool:
 
I admire you for undertaking what seems to me (NOVICE) like a robust project.
Thanks for the kind words. My friend told me to walk away from both boats. This one is probably the easier of the two. I suppose my first time on the water will feel that much better knowing that I saved them from the trash heap. BTW do not cut out your soggy foam. Dry it out. Also, once you get it dry slap some resin over it to seal it if you want.

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You could use the outside of the hull nearby as a mold. 

[Lay up two layers of cloth bigger than the hole onto wax paper and let it set. Sand it with coarse sandpaper, then slide it inside, having previously coated it with filler and epoxy. Lay a few strips of wood or aluminum scrap and put sheetmetal screws through them into the previously-cured patch to hold it firmly in place until set. Then lay up enough cloth (or that non-woven fuzzy stuff?mat?) and epoxy to bring it up "proud" of the bottom. Sand to fair the patch, using a thin plywood block for backing.

Easy-peazy.
Shear genious :) Cant wait to try this out. I will let you know. Maybe if it does not look as bad as my other boat I will show some pictures.

BrainCorrel
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Kawasaki ZXR250
 
Step 1. So far so good. I had trouble getting the plastic to lay flat on the boat so I misted the boat surface with water and it was enough to make it cling. The glass seemed to lay out nicely. Time will tell.
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buy cheap vaporizer
 

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Porpoise2

New Member
"...Shear genious :) Cant wait to try this out. I will let you know..."
Well, not that great. It just occurred to me that the piece you make will be longer than you need; however, if you cut it in half crosswise and overlap the two pieces, you'll still have a better patch than otherwise.
 
The epoxy is drying now. You are right it was a little too wide at the center, but not too bad. The sides were a nice fit and as long as it sticks, I can build it back up in the middle to compensate. FYI I was able to get some access to the back of the patch through the inspection port and then laid a large chain and a few rocks to hold the patch against the inside of the boat.

Thanks for your help. Once it drys I will get some more pictures.
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DR350SE
 
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