# 3M 5200 for Keel/Hull Joint. Is it Paintable?



## Ajay73 (Jun 13, 2011)

Nowhere on the tube of 3M 5200 does it say that this stuff is paintable and sandable. It must be because many people use it for sealing the keel/hull seam. Would someone just confirm that it is for me? Thanks. Also, I use VC17 bottom paint on my 1980 Catalina 27. Can I paint VC17 over the cured 5200? Thanks all.


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## sailingfool (Apr 17, 2000)

Ajay73 said:


> .... It must be because many people use it for sealing the keel/hull seam.....


Do you have good information on that? I hope not, as if the eel is coming off now, then down the road' it'll need to come off again.

I am not sure what to use (never done it), but would wonder that it be 5200...


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## hellosailor (Apr 11, 2006)

That wouldn't be my choice for material and application. Now, if you were going to lower the keel, clean the joint out, rebed it and bolt it back up, that's a good spot for 5200 because it can hold the keel on even without the bolts.

But as a caulking material? It gets very hard, and it isn't going to stick in there any better than, say, a more flexible polysulfide caulk, as best I can tell. Caulking around the _outside _of the keel joint isn't a permanent solution. AFAIK.

A fast call to 3M's excellent 800# will get you a definite answer on the paintable question. Their customer service is among the best on the planet. One phone number, any 3M product, any question gets an answer.


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## Ajay73 (Jun 13, 2011)

I guess a little clarification is in order. My keel developed a little hairline crack between the keel stub and the lead keel. I gound a very small "V" groove between the two. I want to fill it with a flexible material, some kind of caulking. I do not have to drop the keel as there is a very tight seam between the keel and stub. I think I remember forum members using 5200 for this seam. But when I read the 3M info on 5200 no where do they say it is paintable/sandable. I hope this clears it up.

See the last post in this thread.

http://www.sailnet.com/forums/gear-maintenance/65831-g-flex-flexypoxy-keel-hull-joint.html


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## Mobnets (Apr 24, 2011)

I don't know about 5200, but I know 4200 won't hold bottom paint from first hand experience. I have two thru-hulls for the original head (direct overboard discharge) that I intentially shut off the seacocks for and cut the hoses short and plugged/clamped the ends to leave me the option for installing a marine toilet/holding tank/pumpout at some point in the future. For insurance, from the outside, I filled the last inch or so of each with plastic screen impregnated with 4200. Worked great for the application (since 2007), but bottom paint doesn't adhere well to the 4200 "plug". 

Mobnets 
1973 Paceship Chance 32/28 "Westwind"


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## mitiempo (Sep 19, 2008)

The 3M data sheet is interesting reading but it doesn't say anything about painting it. http://multimedia.3m.com/mws/mediawebserver?66666UuZjcFSLXTtlx&EO8TVEVuQEcuZgVs6EVs6E666666--

I wouldn't use 5200 for this application either. 4200 is a better choice.


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## MedSailor (Mar 30, 2008)

hellosailor said:


> That wouldn't be my choice for material and application. Now, if you were going to lower the keel, clean the joint out, rebed it and bolt it back up, that's a good spot *for 5200 because it can hold the keel on even without the bolts. *


So this isn't the first time I've heard this. Where exactly did this rumor come from anyway? 5200 was what was keeping the ocean out of my leaky lapstrake 31ft boat that I lived on for 6 years and during 2 refits I used THREE CASES of 5200 on the hull. Both times I bedded the entire keel with it. When I say bedded I mean I used 5-6 tubes and put a 3/4inch thick layer spread over the top of the keel contact surface which was 8"wide and about 15' long.

Each time the keel came off instantly when the bolts were loosened and the keel weight was allowed to exert itself on the 5200. There wasn't even a 1/2 second of hesitation.

Even without the above experiment (which I performed twice) when you think about it logically it's just not possible. Even if it hadthe legendary adhesive properties that people claim, there is no STRENGTH to it. Ever held a cured bead in your hand? It has slightly less strength than a gummy worm. It can be easily snapped with finger pressure. Could gummy worms (suitably bonded of course) around each keel bolt hold up your keel? I think not.

There is many a legend about it's adhesive properties but I've also never had a hard time getting it off of any surface I stuck it on. I've never had it FALL OFF something it was stuck to, but that's about it.

I once removed several hundred bead-feet of it from my hull so I could recalk the seams. I would get a putty knife under it to separate it easily from the hull, and then I'd play a game of "how long of a bead can I peel off before it breaks." Sometimes it was only a few inches, sometimes I could pull a 10' bead of with gentle hand pressure. There really is nothing to the rumor that 5200 makes a semi-perminant bond. I still have 6 tubes left over and use it for damn near everything.

Now that I'm done wth my 5200 rant, I have enough experience with the product to answer the actual question that was asked.  Can you paint it: Yes. Several different paints have stuck well to it, though I would assume that hard paints (like pettit easypoxy) might be too hard and brittle and crack as the 5200 flexes I had great luck painting it with exactly that product as well as soft ablative bottom paints and also oil based house paint. Stood up well for years.

Paint away!

MedSailor


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## JimsCAL (May 23, 2007)

I've used 5200 to caulk the joint between the keel and hull on my previous boat. Worked fine and took bottom paint without a problem.


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## Ajay73 (Jun 13, 2011)

Thanks all for your responses. I called the 3M customer service number and they said it is paintable. They mentioned the same thing as Medsailor said about harder paints might crack as the 5200 flexes.


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## jwood6111 (7 mo ago)

Ajay73 said:


> Thanks all for your responses. I called the 3M customer service number and they said it is paintable. They mentioned the same thing as Medsailor said about harder paints might crack as the 5200 flexes.


Did they mention what kind of paint was best for the application?


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