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I work with a youth sailing program in Michigan and this past fall we were given a Carter 33 to use for our big-lake sailing program on Lake Michigan.

All things considered, the boat is in very good condition for an early 70's model. A few minor issues with the Volvo MD6A (which should now be resolved, see my post about the "volvo md6a wierd issue"), and the reason for this post, a small wet core issue.

You can see in this image, she had a 1.5' x 1' soft spot on her port side.



I've opened up the top skin using a 2" hole saw and removed all of the wet core. A fan has been used for nearly a month to really dry out the area and everything's bone dry now.

To my question: I know using the West system is best, but man it's $$$. I've thought of using a foam core too, and am not convinced about its characteristics. What about using a water proof Bondo-Hair Long Strand Fiberglass Reinforced Filler as seen here:



I've used this on other projects (different boat), and it held up very well over time.

I figure I can pack the putty in and around the voided core. This method would be a lot cheaper at only $40 / gallon. Are there any downsides I'm not thinking of?

For the top skin I plan on setting back in the original fiberglass "plugs", and using West to fill the remaining voids, then fairing, sanding and painting.

Please remember this is a school ship and although appearance is important, it's not vital. It must look good but show quality isn't necessary and obviously function and cost are key here.

Thanks for the help!

And PM me if you'd like more information about the sailing program.
 

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As you know it's not 'kosher', but I do think it would serve the purpose. However the difficulty will be in actually getting the new 'filler' all the way into all the voids.. this stuff sticks like you-know-what to a blanket and will be very hard to push fully into the voids, esp with the existing pattern of holes.. It's REALLY good at trapping air bubbles ahead of itself.

I'd be tempted to cut the deck skin off altogether in that area, replace the core then glue the patch back down again - not much of a different deck repair/cleanup job than you already got. Plus you can pull and inspect the chainplates while you're at it!
 

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If it were my boat, and what I have done to my boat, is to cut away the top skin entirely, re-core with suitable material such as Klegacel, etc. and lay a new top skin. When completely opening the top skin there is no guessing with rot removal - you can visualize it. Without doing this it will always be a question of remaining rotted core that will continue to spread and infect adjacent areas. Do it right the first time.

Re-coring is not all that hard, albeit time consuming.

Techniques to retain the structural load bearing and stress capability would include the tapering (12:1) of any edges of cuts made to the top skin, full 'filling' all discovered voids, etc. with thickened epoxy and core material to fully restore the deck integrity (safety). :)
 

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I'd be concerned with the bond between the 'skins' and the bondo. While the original lam *may* be polyester; sometimes poly doesn't even want to bond with itself.
I'll second..or is that third?... the recommendation to remove the deck and allow the proper surface prep of the substrate, then go with whatever filler blank and epoxy of choice.
 

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If you want to go "cheaply" you can use a polyester resin instead of epoxy - quite a bit cheaper and likely what was used when making that hull.
I would add some silica fillers and even some short chopped matt and pour it in there.
Replace your plugs (not so easy), and be done with it.

I doubt you need more than 1 gallon of West epoxy to that job. Epoxy has better bonding characteristics than polyester resin.
 

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If it were my boat, and what I have done to my boat, is to cut away the top skin entirely, re-core with suitable material such as Klegacel, etc. and lay a new top skin. When completely opening the top skin there is no guessing with rot removal - you can visualize it. Without doing this it will always be a question of remaining rotted core that will continue to spread and infect adjacent areas. Do it right the first time.

Re-coring is not all that hard, albeit time consuming.

Techniques to retain the structural load bearing and stress capability would include the tapering (12:1) of any edges of cuts made to the top skin, full 'filling' all discovered voids, etc. with thickened epoxy and core material to fully restore the deck integrity (safety). :)

^^^^THIS^^^^ IN SPADES^^^^^^

Ignore all other suggestions. Seriously. Do it right or don't bother.
 

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I would not use Bondo. The core is for strength. I doubt the resin alone would be as strong as the resin over plywood. It will certainly be heavier, and perhaps too brittle. Plus using the plywood will mean that much less resin. Plywood is much cheaper than epoxy resin. As stated above, it is easier to cut out a large section of the deck skin, than to push resin mush through little holes.
If you do a bad job painting anti skid over the repair, no one will notice the repair, only the bad paint job!;)
Good Luck.
Lou
 

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The core needs to be replaced, preferably with the SAME material that was in the original deck: foam, balsa core,cell, etc. Patching with a dissimlar core may create a "hard spot" in the deck, causing the area around it to crack. (Sometimes plywood is used instead of balsa core in high-load areas like under winches. Extra layers of resin & glass are added in these areas to try to avoid the transition-cracks problem.) Bondo shoud NOT be used on boats as a filler. It works on cars (for a while, anyway) because they're not in a marine environment. Bondo ABSORBS water. Like a sponge. I believe the term is "hydroscopic", probably buried somewhere deep in their literature. Think what that means if you use it in your deck and the weather gets below freezing next winter. The water in it will freeze, and expand. Your deck will have a delaminated patch. Any moisture that falls on the deck will have an open passage further inside, to create more rot and delamination in an even bigger area. The same thing happens on cars, but takes longer because they have more opportunities to dry out (garages, hot dry days, cruising at 60mph...) It will mean a little more work to do it right, but... it will be done right. Get some kids involved and they will learn something about planning ahead, besides just fixing stuff.
 

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Go with CalebDs suggestion. Knowing your skills, it is easier for you.
PS, you didn't need all of those holes, and it would have made the job easier.
 

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If it were my boat, and what I have done to my boat, is to cut away the top skin entirely, re-core with suitable material such as Klegacel, etc. and lay a new top skin. When completely opening the top skin there is no guessing with rot removal - you can visualize it. Without doing this it will always be a question of remaining rotted core that will continue to spread and infect adjacent areas. Do it right the first time.

Re-coring is not all that hard, albeit time consuming.

Techniques to retain the structural load bearing and stress capability would include the tapering (12:1) of any edges of cuts made to the top skin, full 'filling' all discovered voids, etc. with thickened epoxy and core material to fully restore the deck integrity (safety). :)
Absolutely correct and can still be done at this point. I would also pull and inspect those chain-plates which are likely the cause of the water intrusion through the top skin of the deck and may have serious crevice corrosion within the thickness of the deck.
 

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I don't know what characteristics of foam coring you need convincing of, but it is the preferred option of professional designers and builders. Balsa core is fine too, but balsa has a greater likelihood of having localized defects.

There is no, and I mean no suitable place to use bondo on a boat. It is junk, and barely works fixing relatively static car parts, on a flexing boat it pops out as soon as the hull flexes at all.

This area must be recored. At this point the large holes you have cut in the deck will prevent that skin from being reused. It has lost too much of its structural integrity (this is why in the yard we use 1/8" holes to test the core, not a 2" hole saw). So you will need to examine the old deck and match its glass pattern, or see if you can find a local fabricator to make a new panel for you.
 

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I don't know what characteristics of foam coring you need convincing of, but it is the preferred option of professional designers and builders. Balsa core is fine too, but balsa has a greater likelihood of having localized defects.

There is no, and I mean no suitable place to use bondo on a boat. It is junk, and barely works fixing relatively static car parts, on a flexing boat it pops out as soon as the hull flexes at all.

This area must be recored. At this point the large holes you have cut in the deck will prevent that skin from being reused. It has lost too much of its structural integrity (this is why in the yard we use 1/8" holes to test the core, not a 2" hole saw). So you will need to examine the old deck and match its glass pattern, or see if you can find a local fabricator to make a new panel for you.
Greg is correct with his assessment, above. There is, however, a method for re-glassing the damaged/ removed deck area and then closely replicating the original non-skid pattern. See (click on) MAS Flex Mold Non-Skid Patterns. Patterns can be found at MAS Epoxies
 
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