Sealing transom shield opening ... type of resin???

piperca

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I'm cutting the existing openings on the transom of my boat to install a different transom shield (280s to DP-Es). What fiberglass resin product should I use to seal the opening? Someone suggested penetrating resin, but it's $50 a pint ... ouch! Is there another resin product that is not as expensive that will do the job?
 

zool

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Carefull just filling in a VP outdrive cutout, if the new hole is smaller, which I believe it is on the later DP series, your bolt holes will be in the void area. You really should install a new transom, or at least lap the filler board at least 6-12 inches over the existing wood, in all directions, just a heads up ;)

Epoxy laminating resin, about $80 a gallon with catalyst, would be best if not coating with gel coat, polyester resin, less than half that, will work fine too if gelling
 

Woodonglass

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Uhmm Transom Openings??? Transom Shield??? Not sure I know that Terminology. Got any pics?? What boat is this for?? I would think a Standard ISO Polyester Resin would work if you are going to be coating the finished product with Gelcoat. If Painting,then Epoxy would be a good choice as well.
 

zool

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Uhmm Transom Openings??? Transom Shield??? Not sure I know that Terminology. Got any pics?? What boat is this for?? I would think a Standard ISO Polyester Resin would work if you are going to be coating the finished product with Gelcoat. If Painting,then Epoxy would be a good choice as well.

Actually,after thinking again about it, the dp-e is a bigger hole than the old 280....I think expanding the hole is doable if the transom is solid...
 

Woodonglass

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AHHH, I get it now, existing holes for I/O outdrives. I'm NOT an Outdrive kinda guy but ZOOL is so you're in good Hands. Like he said and me too, If you plan on Gelcoating you have to use Poly resin. If not then Epoxy would be the way to go.
 

piperca

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Zool, yes, the holes are larger and the hull is solid. I did not intend on using gelcoat, as I didn't think it necessary. I am, however, freshening up the gelcoat finish in the bilge, below the engines, so it wouldn't be too much trouble to add a lick of gelcoat to the opening of the where the transom shields will be. Would it make much difference?

BTW: Epoxy resin was a product that was offered to me this afternoon, but I wasn't sure if it was sufficient. I am a total newby, when it comes to fiberglass/resin work. Thanks for the input, thus far!
 

Woodonglass

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You know, you'll get a Lot more and better advice/responses if you post some pics of your boat and the area of repairs that your working on. It's kind of an unwritten rule here on the forum "Without pics...it never happened!!!!":D:eek:
 

zool

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Since its a visible area, youre gonna want to finish it with something, (uncoated resin repairs are ugly lol). Pigmented epoxy lacks the necessary UV protection, so it should be coated, even in the engine compartment, it may chalk. Matching paint or gel is equally difficult, so pick your poison and get er done. Polyester resin with some chopped strand mat, and some cabosil, and a gel repair kit should get you there, at minimal expense.

And as Woody said, open a photobucket account and post the pic url.....
 
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piperca

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Okay, here is the only photograph that I have of the area I am referring to. The original opening feels like bare wood; however, it is a dyed black color. It certainly does not appear to have any fiberglass over the cut edge. I'm assuming they used a penetrating resin of some sort. BTW: The boat is a 1980 28' Skipjack Flybridge.
 
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Rickmerrill

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That link just takes us to photobucket.com. Since the upgrade the only reliable way to post pictures is to get a free photobucket account, upload there, copy the IMG link and paste it directly into the text of your post.
 

piperca

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That's what I did and it keeps changing the URL ... so, here you go!


P4060004.jpg P4060004.jpg
 

zool

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Okay, here is the only photograph that I have of the area I am referring to. The original opening feels like bare wood; however, it is a dyed black color. It certainly does not appear to have any fiberglass over the cut edge. I'm assuming they used a penetrating resin of some sort. BTW: The boat is a 1980 28' Skipjack Flybridge.

penetrating resin is just thin resin, from the factory, my openings were just barely coated, looked like raw wood. Fast forward to now, a portion of my rot was at the openings. The reason for the csm (glass) is that poly resin by itself is brittle, and cracks allow water penetration, epoxy is elastic, and remains water resistant. You need to coat the newly cut opening, Poly resin/csm and gel, or epoxy resin and paint is the norm.
 
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undone

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Like zool said, penetrating resin (epoxy) is just thinned down epoxy , the thinning process can actually destroy the physical properties, this includes water resistance, so stay away from those types of products. It's a good idea, but the chemistry doesn't work.
 
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piperca

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Okay, epoxy resin it is.

Also, the bolt holes from the old transom shield; I was going to use wood dowels soaked in epoxy resin to seal them ... sufficient?
 

Scott Danforth

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when I did my transom, I made the hole a bit larger (by 1/8") filled it with PB and smoothed it with a bondo spreader. on a few boats I used epoxy paint.

if you have water sitting in the bilge long enough to soak thru the epoxy paint, you will have more issues than a wet transom.
 

piperca

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PB? Sorry, you got me there.

The boat lives on a trailer, so there is no chance that water will sit for more than a day or two.
 

GWPSR

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PB? Sorry, you got me there.

The boat lives on a trailer, so there is no chance that water will sit for more than a day or two.

PB = Peanut Butter, a nickname for thickened resin. Thickeners can be anywhere from wood flour (some have actually used wheat flour) to fumed silica (Cabosil), and some formulations add 1/4" chopped fibers (kitty hair) for extra strength, but for bolt holes, filling with any thickener will be fine. I'd avoid the flours for below the water line or areas that can see weather.

Even better is to grind out a small dished area on the inside after the PB cures, and lay a small cloth patch over the inside of the hole and sand fair.
 

undone

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And depending on the exact "epoxy paint" it may have very little water permeation resistance. Many epoxy paints don't share a great deal of chemistry with true epoxy, but evidently enough for the marketing department to run with the term. Most paints aren't very water resistant, they are applied very thin and then have a good deal of solvent added for leveling and ease of application, neither of these helps in resisting water.
 
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piperca

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The holes will be under the outside flange of the transom assembly, so I'm not too concerned with exposure from the outside. So, let me get this right; if I chop up a few pieces of fiberglass (into tiny pieces) and mix it with my epoxy resin, that should be sufficient to fill the bolt holes? When you say "peanut butter," is that the consistency I'm looking for? Is there any adjustment in the amount of hardner used for this process?
 

undone

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There are several things you can use to thicken the epoxy, the only one that does a good job of stopping it from sagging is Fumed silica, it goes by several names, Aerosil and Cabosil are two of them. Other stuff will thicken it, but won't do a good job of stopping the sag. Most will mix silica with fibers to form a stronger product, micro spheres will help make it smoother, lighter and easier to sand. But on smaller jobs like this it isn't that critical what mix you use.

You always use the same mix ratio with epoxy, you differentiate between gel times by using a fast, medium or slow or hardener.
 
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