Caulk Choice

Stingrayaxe

Stingrayaxe

Active Member
Oct 29, 2015
347
Crystal Lake
Boat Info
2009 Sea Ray 205 Sport
2015 Chevy Tahoe, Max Towing
Engines
5.0 Merc Alpha 1
What's the caulk preference for mounting smart tabs on the transom? 5200 too permanent? 4200? Life Seal? I could over drill, fill with epoxy and drill pilot holes in the epoxy but is this overkill? What advice can you give me? Thanks.
 
The best approach is to over drill and fill with epoxy. If you don't want to take that approach, then 3M 5200. The last thing you want is your transom rotting.
 
Overdrill, pull some coring out and fill with epoxy. Once cured, redrill and install with LifeCalk.
 
It's not really "needed" to overdrill, but it is definitely not overkill. Instead, I would call that "best practice". Use LifeSeal, LifeCaulk or 4200. Actually, any decent "sealant" is all you need as a strong adhesive is NOT needed/wanted. 5200 is the wrong product for this application.
 
Understood. The instructions and videos that come with the tabs just talk about drilling pilot holes and sealing with caulk. I'm very concerned about drilling any holes at all in the transom so the over drill method seemed like a better choice to avoid water intrusion. I was weighing that with the need to drill bigger holes and the time needed to let the epoxy cure enough to finish the project. Is Marine-Tex a good choice for the epoxy? If so I'll put on my big boy pants, get the big drill out and have at it. I'm anxious to test the boat with the addition of the smart tabs. I've been wanting to do this for a while.
 
Stingrayaxe said:
Understood. The instructions and videos that come with the tabs just talk about drilling pilot holes and sealing with caulk. I'm very concerned about drilling any holes at all in the transom so the over drill method seemed like a better choice to avoid water intrusion. I was weighing that with the need to drill bigger holes and the time needed to let the epoxy cure enough to finish the project. Is Marine-Tex a good choice for the epoxy? If so I'll put on my big boy pants, get the big drill out and have at it. I'm anxious to test the boat with the addition of the smart tabs. I've been wanting to do this for a while.
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Marine-Tex should work fine. Just be sure to get it all the way in the holes (no voids). I personally would use West System epoxy thickened with colloidal silica, just because I have that on-hand. I can control the epoxy thickness by the amount of silica added.
 
If you put the MT in a sandwich baggie and snip the corner off you can use it like a baker's piping bag and push the corner into the back of the hole and fill that way - to avoid air voids.

However, if you're asking for opinions on what product to use... I'd use unthickened epoxy resin since (1) the hole is small and (2) it will absorb into any coring better than thickened epoxy would (at least it "should", anyways). To do this, get a syringe (the kind that comes with kiddie medicine would work) and place a piece of masking tape over the hole. Open the top, center of the tape just enough to squirt the epoxy in. Don't worry if you end up with too much epoxy - you can sand/grind it smooth later. I would also take one extra step and that would be to chamfer the hole that you drill - basically use a drill bit twice the size and go in just a bit to create the chamfer. This will give better adhesion. Plus, you can re-chamfer the hole so there's a larger area for sealant.
 
Lazy Daze said:
If you put the MT in a sandwich baggie and snip the corner off you can use it like a baker's piping bag and push the corner into the back of the hole and fill that way - to avoid air voids.

However, if you're asking for opinions on what product to use... I'd use unthickened epoxy resin since (1) the hole is small and (2) it will absorb into any coring better than thickened epoxy would (at least it "should", anyways). To do this, get a syringe (the kind that comes with kiddie medicine would work) and place a piece of masking tape over the hole. Open the top, center of the tape just enough to squirt the epoxy in. Don't worry if you end up with too much epoxy - you can sand/grind it smooth later. I would also take one extra step and that would be to chamfer the hole that you drill - basically use a drill bit twice the size and go in just a bit to create the chamfer. This will give better adhesion. Plus, you can re-chamfer the hole so there's a larger area for sealant.
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This seems like the way to go. I knew enough to chamfer the holes but thanks for the reminder. Nobody around me carries 4200 in stock or marine epoxy. So now its off to WM for what I need. Only 26 miles one way. I do want to do it the right way. I guess its the price I need to pay. The instructions call for a 7/32" pilot hole. What size over drill hole would you recommend? Really appreciate the help with this!
 
Roughly 1-1/2 to 2 times the size of the thickness of the "threads" portion of the screws. It's not an exact science, though.

Since you're just doing a small repair, you might want to just use polyester resin, instead. It'd be a lot cheaper and absolutely, 100% fine. The only downsides to poly is that you have to watch your mix ratio since you're using drops and also watch your pot life time. Poly is stinky, too.
 
Lazy Daze has this process nailed. I would only suggest staying with epoxy for the reasons mentioned earlier.
 
You may get lucky and have solid fiberglass. That's what I had at the ends of my transom. See my post here
http://clubsearay.com/index.php?threads/lumitec-lighting-install.103357/#post-1216604

I filled a large 1" diameter string with marinetex and shot it in from the back of hole outwards. Otherwise your guaranteed to get air pockets.

Also realize as you think you are oversizing the hole it's hard to redrill at the same angle. So being slightly off in angle ends of poking through your oversized hole and into the wood transom.

Also don't use straight epoxy without thickening. It's generally brittle and not good for screw threads biting in.
 
pyro said:
You may get lucky and have solid fiberglass. That's what I had at the ends of my transom. See my post here
http://clubsearay.com/index.php?threads/lumitec-lighting-install.103357/#post-1216604

I filled a large 1" diameter string with marinetex and shot it in from the back of hole outwards. Otherwise your guaranteed to get air pockets.

Also realize as you think you are oversizing the hole it's hard to redrill at the same angle. So being slightly off in angle ends of poking through your oversized hole and into the wood transom.

Also don't use straight epoxy without thickening. It's generally brittle and not good for screw threads biting in.
Click to expand...

I would never be that lucky. I think I will go with the Marine-Tex. Mostly because it is what I have on hand and also it seems to be a good product for the job. I'll use Dennis's piping bag method. Squirt a little in the hole. Stir it around so it covers the bottom and sides of the hole and top off. Even if there is a small air pocket the wood would be protected and the 4200 will take care of the rest. There are 8 mounting screws on the base plate. The plastic will fail before a screw pulls out. I need to get this done and go boating. Reaching the 70's finally today. We are very close. Thanks again for all the help.
 
Stingrayaxe said:
I would never be that lucky. I think I will go with the Marine-Tex. Mostly because it is what I have on hand and also it seems to be a good product for the job. I'll use Dennis's piping bag method. Squirt a little in the hole. Stir it around so it covers the bottom and sides of the hole and top off. Even if there is a small air pocket the wood would be protected and the 4200 will take care of the rest. There are 8 mounting screws on the base plate. The plastic will fail before a screw pulls out. I need to get this done and go boating. Reaching the 70's finally today. We are very close. Thanks again for all the help.
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That'll work out just fine.
 
Wood+moisture+warmth =s dry rot. Then the building collapses. I could offer examples. Weyerhauser is not happy to talk about it theirs. I don't think there are exceptions for boats. If you are going to expose previously encapsulated wood, the first step would be to treat it with as aggressive a fungicide as you can find. The sort you would use on cut direct burial timber. Course the good stuff was banned in the U.S. about a decade ago.
735845330080.jpg
 
Arminius said:
Wood+moisture+warmth =s dry rot. Then the building collapses. I could offer examples. Weyerhauser is not happy to talk about it theirs. I don't think there are exceptions for boats. If you are going to expose previously encapsulated wood, the first step would be to treat it with as aggressive a fungicide as you can find. The sort you would use on cut direct burial timber. Course the good stuff was banned in the U.S. about a decade ago.
735845330080.jpg
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I'm not sure what the point of a copper based fungicide would make if I'm re-filling the hole with epoxy. Then again maybe that gallon of creosote that I have been hanging on to might finally have a purpose.;) I'll have some left over of you need to treat your plywood bow cover.
 
Arminius said:
Wood+moisture+warmth =s dry rot. Then the building collapses. I could offer examples. Weyerhauser is not happy to talk about it theirs. I don't think there are exceptions for boats. If you are going to expose previously encapsulated wood, ...
Click to expand...

Most wood rot is due to the growth of fungi. All fungi need to grow is a source of spores, fresh water moisture, warmth between 60 and 95 degrees and nutrients = wood. Fungi cannot grow with salt water moisture (pickling the wood) or without oxygen (suffocating the fungus). To stop fungus growth in a boat, just eliminate all access to oxygen by completely sealing any penetrations through the fiberglass.
 
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"Complete sealing" is conjectural. Thickening the resin is not going to help.
 
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