wishtofish
New Member
Only done a little bit of Fiberglass but now need to repair delaminated drain plug glass. My thought is to fill the existing hole with 1708, then drill new drain hole. How would you go about it?
Fiberglass advice
- Thread starter wishtofish
- Start date
Independent Marine
Member
Are you able to access the inside? Might be a good idea to attach a board with a release agent so you can remove it later. That way you have a backer board to pack the fibreglass material against.
easydoesit
Well-Known Member
Did something similar.
Filled and then drilled holes through transom to fit new deck drains. Used chopped glass fibre and faster catalyst. Worked well. Discovered that bigger batches generate more heat and set faster - that was exciting.
Also a bit tricky getting the holes aligned 90 degrees to the transom. Glued and sealed in place with 5200.
Prep is important for this. Between the internal and external fibre glass layers it was necessary to remove any wet wood material to stop any rot and get a solid bond. Basically I created a solid fibreglass plug in the hull and then drilled a smaller diameter hole through it.
Hope this is useful.
Filled and then drilled holes through transom to fit new deck drains. Used chopped glass fibre and faster catalyst. Worked well. Discovered that bigger batches generate more heat and set faster - that was exciting.
Also a bit tricky getting the holes aligned 90 degrees to the transom. Glued and sealed in place with 5200.Prep is important for this. Between the internal and external fibre glass layers it was necessary to remove any wet wood material to stop any rot and get a solid bond. Basically I created a solid fibreglass plug in the hull and then drilled a smaller diameter hole through it.
Hope this is useful.
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seachicken
Well-Known Member
How much have you feathered it out? Is there going to be a layer of cloth on the outside? As @easydoesit said chop strand mixed in resin. And I would use unwaxed vinyl esters resin, especially if you are going to gel coat it.
wishtofish
New Member
That part of the transom lucky is glass only with no exposed wood. I have easy access on both the inside and outside via the bilge. My plan was to glass in a layer on the inside of the bilge across the hole with some 1708 then build it up from the inside out. How far out should I feather the outer layer of glass
seachicken
Well-Known Member
That will depend on how many layers of cloth you'll put on. If the structure is solid I would do a layer of CSM and then 1 or 2 1708 (or a few of CSM) on the outside but I'm not an expert. I would be hesitant to remove too much original structure, maybe go down 1/8" at the hole and an inch of radius around for each layer. Fish bump TV and boat works today are good on the YouTube. CSM bonds better to existing structure and I believe is better for first layer but is recommended to be used with ester based resin. Lots of people would just fill the hole with resin and it would probably be fine, I think if you have a couple layers inside and out it will be a great repair.
To get maximum strength from a hole repair 12:1 length to thickness for feathering is a common recommendation. Is that necessary in your case, maybe not. Being at the bottom edge of the transom, it's probably a low stress location so not as important to have a very high strength repair. That being said, repairs like this rely totally on the adhesive strength of the resin used. If you're using polyester or vinyl ester, that's not very strong, hence the huge taper.
Here's a good reference for learning basic fiberglass repair techniques.
Doubleheader
Well-Known Member
Epoxy products are always a good choice for below the waterline repairs, same process as with poly/vinyl but wouldn’t need to grind out as much for a sturdy repair. Gel coat doesn’t bond nearly as well to epoxy but it’s not a heavy wear area. Remove the amine blush, scuff with 40 grit for a good mechanical bond and it should look fine for many years. Even if the gelcoat doesn’t bond great epoxy is waterproof.
