Restoring an oldie, this should get interesting...
- Thread starter Brian N
- Start date
Don't use pressure treated, the resins will not penetrate or adhere well due to the moisture and chemicals in the PT plywood. If you can't get marine ply, use a top quality exterior plywood, or a composite board like Koosa or divinicel (sp?) foam board. I'd use epoxy for the layup, its more money but low VOC's and longer working times, plus better strength. I've never used foams, but wood is very forgiving for the inexperienced so plywood is a good choice. If you have a custom lumber yard around, they can usually order marine ply for you. I did that in my area a few times, but hang on to your wallet, the stuff isn't cheap. Last piece of 3/4" marine ply I bought was over $100 a sheet.
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- Mar 28, 2001
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So, my next door neighbor wandered over to chat and see what all the noise in the backyard was.
As it turns out, he has a 4X8 sheet of 3/4 marine plywood taking up space in his garage and he's happy to get rid of it. So that sorts that question out.
Here was our fun today...
The flotation foam in the bow has seen better days...since we're in here anyway. Number two son decided to pitch in...
The transom wood, ugly!
Oh joy! The front crosspiece is rotted too! This just gets funner all the time!
And just for fun...here's the bow hook and it's backing plate. What's wrong with this picture?
Ready for a new transom.
The show goes on, more to follow. We have discovered that the floor is covering up some very waterlogged foam, trying to decide whether to cut it out and replace (the structure is solid) or just leave it be. Thoughts?
As it turns out, he has a 4X8 sheet of 3/4 marine plywood taking up space in his garage and he's happy to get rid of it. So that sorts that question out.
Here was our fun today...
The flotation foam in the bow has seen better days...since we're in here anyway. Number two son decided to pitch in...
The transom wood, ugly!
Oh joy! The front crosspiece is rotted too! This just gets funner all the time!
And just for fun...here's the bow hook and it's backing plate. What's wrong with this picture?
Ready for a new transom.
The show goes on, more to follow. We have discovered that the floor is covering up some very waterlogged foam, trying to decide whether to cut it out and replace (the structure is solid) or just leave it be. Thoughts?
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- Jan 1, 2000
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Cutting out old foam SUCKS. A good pressure washer will decimate it and make short work of stripping off the remnants that are still adhered to the fiberglass.
The only fun part of stripping out old foam and pouring new is the leftover new foam. Takes less than half a paint cup each of part A and part B to easily overfill a pair of boots, if you just so happen to have a co-worker that richly deserves it.
The only fun part of stripping out old foam and pouring new is the leftover new foam. Takes less than half a paint cup each of part A and part B to easily overfill a pair of boots, if you just so happen to have a co-worker that richly deserves it.
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You'll both be kicking yourself later if you close up that waterlogged foam. You've already got the cap off and you're most of the way there - be crazy not to do it now when 80% of the work is already done. Especially if it's so rotted it's coming right out like that.
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Angle grinder and child labor = no need to break out the saw.
Don't replace any foam. It was an absolutely stupid idea just cuz it floats. Kinda like everyone jumping on the 'Gluten' bandwagon.
Get out all the bad wood. Any left in that has rot will migrate to your good wood.
As for marine grade ply, it's used for the hull or any part that touches water. Good exterior ply will work fine..as long as you paint epoxy on all surfaces. 1 coat is usually fine for flat areas but end grain will need a couple. Areas that covered foam with fiberglass can just be replaced with ply. Don't drill out limber holes. That's another bad idea. They hold water. Cut triangles in bottom corners in bulkheads for drainage. It will keep compartments dry by allowing free drainage.
Make a template for the transom. Use 2 sheets of 3/4" ply. Don't cover holes in the transom yet. In fact, you will probably need to drill more holes in a pattern. You attach the ply to the fiberglass skin with good ol wood screws that can be easily removed and covered later. The second sheet of ply for the transom will just be screwed to the first one.
These sheets of ply will be painted with epoxy and allowed to start first cure. Then thickened epoxy can be painted or troweled between the transom and ply. The thickened epoxy will also fill any unused holes in the transom skin. The same procedure for the second ply.
Now about epoxies, they have a long second cure period and will readily bond a fresh application to an older application. They are also chemically compatible to polyurethane and will bond as long as the second cure hasn't finished it's full cure.
The other thing about epoxies is an Amine Blush, which is a waxy coating that surfaces during the curing process. Tap Plastics has marine epoxies with lottle or no blush. I've never had to wash with soap and water between coats of epoxy. Tap Plastics also gives you a full gallon (or quart) in their kits. WM and all other providers of epoxy give you the amount in their ratio mix. You pay for a gallon of resin but only get 2/3 or 3/4 of a gallon. Total rip off.
My last major repair was also my transom and replacing all the wood from the helm to transom. I used 25 gallons of epoxy but I did more than replace what was bad.
Get out all the bad wood. Any left in that has rot will migrate to your good wood.
As for marine grade ply, it's used for the hull or any part that touches water. Good exterior ply will work fine..as long as you paint epoxy on all surfaces. 1 coat is usually fine for flat areas but end grain will need a couple. Areas that covered foam with fiberglass can just be replaced with ply. Don't drill out limber holes. That's another bad idea. They hold water. Cut triangles in bottom corners in bulkheads for drainage. It will keep compartments dry by allowing free drainage.
Make a template for the transom. Use 2 sheets of 3/4" ply. Don't cover holes in the transom yet. In fact, you will probably need to drill more holes in a pattern. You attach the ply to the fiberglass skin with good ol wood screws that can be easily removed and covered later. The second sheet of ply for the transom will just be screwed to the first one.
These sheets of ply will be painted with epoxy and allowed to start first cure. Then thickened epoxy can be painted or troweled between the transom and ply. The thickened epoxy will also fill any unused holes in the transom skin. The same procedure for the second ply.
Now about epoxies, they have a long second cure period and will readily bond a fresh application to an older application. They are also chemically compatible to polyurethane and will bond as long as the second cure hasn't finished it's full cure.
The other thing about epoxies is an Amine Blush, which is a waxy coating that surfaces during the curing process. Tap Plastics has marine epoxies with lottle or no blush. I've never had to wash with soap and water between coats of epoxy. Tap Plastics also gives you a full gallon (or quart) in their kits. WM and all other providers of epoxy give you the amount in their ratio mix. You pay for a gallon of resin but only get 2/3 or 3/4 of a gallon. Total rip off.
My last major repair was also my transom and replacing all the wood from the helm to transom. I used 25 gallons of epoxy but I did more than replace what was bad.
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- Mar 2, 2000
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Should a layer of mat go in between the ply layers? I thought that helped with adhesion. BTW Coosa Blue Water 26 comes in different thicknesses and can be layered. I used this approach when I redid the fore deck of our boat. It's easy to work with and once in place it never rots.
The one thing I liked about West was the pumps measure it out for you. That and they have the gun ready thickened epoxy for filling cracks. Six-10 while expensive is really handy to work with once you have ID'd all the cracks that need some fill.
The one thing I liked about West was the pumps measure it out for you. That and they have the gun ready thickened epoxy for filling cracks. Six-10 while expensive is really handy to work with once you have ID'd all the cracks that need some fill.
Absolutely you can use any type of glass sheets between and over any area. I added up to 4 layers roving to the inner hull so my stringers and bulkheads had a surface that would fit the straight edges of stringers and bulkheads. These connections also had glass and thickened epoxy added at the 90* angles to build up the 'cove' to build up the surface area between connections. It's all in the directions of that book that I forgot the name of. Something about fixing a row boat or some such. It should be in any fiberglass repair display.
Another thing, Always use the slow cure. A hot cure will actually make the epoxy more brittle. And slow cure is more forgiving.
It'll also take a while guesstimating the amount of resin/hardener to mix for each step of the way. You can get away with using smaller batches with epoxy if you have to mix another batch real fast. Doesn't work with polyester resin (regular fiberglass resin). The only time to over mix is when gluing up large surface areas like transom or building up multiple layers of plywood.
It'll also take a while guesstimating the amount of resin/hardener to mix for each step of the way. You can get away with using smaller batches with epoxy if you have to mix another batch real fast. Doesn't work with polyester resin (regular fiberglass resin). The only time to over mix is when gluing up large surface areas like transom or building up multiple layers of plywood.
- Joined
- Mar 2, 2000
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Keeping the components in a refrigerator will also assist in slowing down the cure. When working with thickened epoxy over a large area like a transom, I would highly recommend keeping the parts in the fridge.
Once it starts to kick you are in deep if you are not ready or part way through application and assembly.
Once it starts to kick you are in deep if you are not ready or part way through application and assembly.