5200 sealant for small holes - problem

I've seen this recommended all over for it's flexibility and toughness (over JB Weld and other altrnatives). But I tried it and am having an issue - probably cause Im' not using it for the right purpose...

My boat has too many holes drilled in the transom, more than I need to install the new one I'm builing. Aside from sealing up the individual holes, I'm going to seal around the edges of the boards as well. On top of that, I'd like to close up the ones that are not going to be used... So, I got some 5200 and put it in the holes and it ran down the side of the boat. Too liquid, this stuff...

Has anyone used JB Marine Weld? Would this be better for this particular application? Any recommendations would help!

You are going to have to apply small amounts at a time to build it up, find something to plug the hole and go over it with 3m, or you could treat it like you cut yourself shaving. A piece of paper or cardboard will keep it in the hole most of the time. Problem is when you go to remove it some will remain. Or just keep smearing it until it tacks. Practice of each of these methods will seal your hole, might take a day or two in between first and last coat. Not really an easy product to plug large holes but haven't found a better substitute. Honestly never looked, stuck with what worked. It may be a pain to apply but results are worthy.

Yeah...play with it. Personally mine wasn't runny at all but I would suggest maybe trying a little masking tape on the back side of the hole and then filling up from the front...

3M 5200 is a little on the liquid side and takes up to a week to cure. I've had pretty good luck with Fast Cure 5200. I've used it to fill holes on vertical surfaces and it stays in place pretty well, as it's a little thinner consistency than toothpaste.
Fast Cure 4200 is also a good product and if it ever has to be removed and the job done over, it comes off a lot easier than 5200. That stuff is really good but it was formulated to be basically an adhesive and it's primary use has always been hull/deck joints. It has to be sawed/cut off.

I'm not sure what others think about this idea but I'll throw it out there. I wouldn't seal around the bottom edges of the transom where the wood contacts aluminum. If the transom leaks, the water is trapped between the wood and aluminum and you might not know you have a leak. The trapped water causes the wood to rot at an accelerated rate and can pit the aluminum. And in some cases, the aluminum could be pitted bad enough to be beyond a simple repair. For me, if I know I've got a leak, I can take steps to stop the leak and save a lot of work in the long run.

I agree with that as well...I would want to see the seeping water.

5200 is more of an adhesive than it is a sealant.

Go with the JB Weld. Put some tape on one side of the hole and place some JBW on the other. You may have to let the JBW sit for 20 min or so to harden up a bit so it won't run too much on you, more than one application may also be needed. Sand smooth and paint over when dried, you'll never know there was a hole there. The 5200 is more for putting around nuts and bolts to insure water tight integrity than for sealing open holes, IMO.

JB weld is known to crack on tin boats...a few of us have experience with that. Don't do it...

Many, many people have used 5200 with great success.

have you looked to see how much it would be to get them welded?

I've used 5200 a ton of times and NEVER had it run. Hate to say it, but it sounds like yours may have separated. Stored too long....too hot....too cold...or something. Call 3M. My bet is that they will send you another batch..or send you back where you bought it.

Usually, I have to use a spatula to smear the stuff on, or my finger. Strange....

R

Each time I used 5200, it is very runny so use it sparingly. A little goes a long way. To plug unwanted holes, I first install a bolt and nut with 5200 in the hole, then grind down the excess thread of the bolt. I've used it to mount stuff on both my tin and fiberglass boat with great success. It does take a few days to totally cure depending on the weather.

Jdholmes said:

JB weld is known to crack on tin boats...a few of us have experience with that. Don't do it...

Many, many people have used 5200 with great success.

Click to expand...

Unless your putting the JBW on a seam that was previously welded, cracking should not be an issue. If a boat flexes enough to crack JBW on a small drill hole on a non stress point in the hull, I'd seriously be concerned about the structural integrity of the boat. I patched several holes w/ JBW on my Landau, many in the transom. No problems yet, benefit is you can sand smooth. 3M 5200 is a great product, and I've also used that for many applications and have had no issues. Sounds like you can go either way.

Thanks everyone for all the great replies. Great point about not totally sealing off the transom, I'll heed that advice.

Try marine tex.

Stuff seems to be curing. Man, it's slow. I'm sure the cooler nights doesn't help.

Anyway, I can see some hope now, layering it up slowly seems to be doing the trick.

New question - can you sand it smooth once it's finally dried?

Yes I believe some folks have had luck sanding. Mind took a couple weeks to really get hard, because I didn't get the quicker setting version. I did thin it down a little too with acetone on my finger to make it look clean...plus I think ambient temperatures and humidity can for sure alter the setting times.

It looks like six guns sanded his in the pics.

This weather has really made the curing process interesting. Up to the 80s during the day, but at night it gets in the 40s/low 50s. So it cures in "spurts."

At the same time, I've been putting coast of spar urethane on a replacement transom.. same deal, but at least it still dries within 24 hrs (at least dry enough for the next coat).

nomowork said:

Each time I used 5200, it is very runny so use it sparingly. A little goes a long way. To plug unwanted holes, I first install a bolt and nut with 5200 in the hole, then grind down the excess thread of the bolt. I've used it to mount stuff on both my tin and fiberglass boat with great success. It does take a few days to totally cure depending on the weather.

Click to expand...

^^^This, or use a rivet.