Sealing joints between teak coming bds and deck

rperrone · Post by **rperrone** » Jun 20th, '11, 14:22

Advice , tips , pointers on caulking joints between teak and fiberglass.
Our 33 has need for new sealant. We believe we are getting some water (not much) infiltration from the joint between the cockpit coming boards and the deck joint. We purchased 3M 4200 white thinking it has adhesion and elastic qualities to solve the problem. One concern is whether to scrape out all old material before undertaking this project? Also, what if any pretreatment / primer is required? And is this the correct application of 3M 4200?

SurryMark · Post by **SurryMark** » Jun 20th, '11, 17:57

On the 27, anyway, the coaming is screwed to the deck/cockpit side. If there were no caulk, there would be a slight gap and water would seep onto the cockpit seat. I just knifed out the bad caulk and resealed it with LifeCaulk, which is much easier to apply and clean up. Adhesiveness is not needed here.
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Steve Laume · Post by **Steve Laume** » Jun 21st, '11, 08:30

Mark is right in that all you need is caulk for this joint.

Hopefully the PO knew this too. If not you will soon discover why you don't need anything stronger when you go to remove the old stuff. A triangular scraper works very well in this area.

This would be the perfect time to treat your teak combing boards with your finish of choice. You can then seal onto the coated wood. This will prevent water from getting under the edge of the finish and make it easier to mask off the area as well as clean up the caulk.

Don't forget to wet your finger, Steve.

Troy Scott · Post by **Troy Scott** » Jun 21st, '11, 10:18

Some folks have made the mistake of sealing the bottom edge as well. That just traps water if the upper joint leaks.... Sealing top and bottom might would be OK if the entire board is thoroughly bedded in compound. It probably isn't.

Good luck!

Gary H · Post by **Gary H** » Jun 21st, '11, 12:15

The following short article is the best that I have come across on explaining the use of the appropriate sealant for different uses (coaming, rails, cleats, hatches, ports, etc.)

The more I had read, the more confused I became - but this article spelled it out clearly (at least for me). Hope it helps.

http://blog.dankim.com/2009/04/24/marine-sealants/

Jim Cornwell · Post by **Jim Cornwell** » Jun 21st, '11, 17:04

Having just begun the long, long delayed teak resuscitation project on Yankee by scraping one of the coamings last weekend, I've been pondering this sealant question, too. The joint along the outside of the coaming is what we would call in a building a "dynamic" one, meaning that it's subject to quite a bit of movement and has to maintain its integrity in spite of that fact. It's also a joint between dissimilar materials, which introduces the problem of adhesion - what sticks to gelcoat may not stick as well to teak, while remaining elastic. I wonder what would happen if the joint wasn't sealed at all and water were allowed to run down the crevice and be carried away by the built-in gutters around the cockpit lockers. This has actually been happening on Yankee for quite some time, with no apparent ill effect (maybe the wood's rotten back there - I dunno). I can say that a much cleaner looking joint would be the result of skipping the sealant! What say the sages? Jim.

Troy Scott · Post by **Troy Scott** » Jun 21st, '11, 18:09

I don't know if i qualify. Maybe I do since lately I feel about 90 years old.
If the space in question isn't sealed from the top, and you regularly sail in conditions where spray or rain reaches the side decks, you will have a wet seat much of the time.
WRT the sealant not sticking well to teak..., consider that it would be wise to varnish (or Cetol) before caulking this gap. Then the question becomes: Does the material stick well to both varnish and gelcoat?

Steve Laume · Post by **Steve Laume** » Jun 21st, '11, 20:29

I must admit that I sailed our Typhoon for several years without the joint being caulked at all. There was never really any problem with water leaking in. If it was nasty enough to have water leaking in around the combing I was already wet or had on foul weather gear.

The main reason for not caulking the joint on the TY was that the combing boards were held in place with finish washers on the screws instead of being bunged. Without the caulk it was easy to take them off each winter and refinish them on the bench, Steve.

rperrone · Post by **rperrone** » Jun 22nd, '11, 15:30

One thing I failed to include was that on the 33 there is
inlaid teak in front of the companionway. Some 33's have there
traveler mounted there. Ours is on the bridge deck. The teak/ glass joints there are also in bad shape.

RMeigel · Post by **RMeigel** » Jun 30th, '11, 14:27

I have used Dolphinite bedding compound between the coaming board and fiberglass on my CD 27 - but I remove the coaming board. I do not slather it over the entire hidden surface but along the upper edge where it isn't quite visible. Water gets trapped but evaporates quickly. The staying power of Dolphinite is far longer than Life Caulk for this purpose. It is also less messy than Life Caulk. In my experience Dolphinite is not best suited for applications that are visible.

Robin Meigel
s/v Pacem
1979 CD 27

SurryMark · Post by **SurryMark** » Jun 30th, '11, 14:57

If I didn't have some caulk well-stuck in that space already, I definitely would not have cleaned out the loose stuff and added more LifeCaulk. If water is coming down the deck, you're heeled over and it should run out. In rain or flying buckets of spray, you won't notice the bit that weeps through. This is one area of Cape Dory maintenance that should not cause any headaches, IMHO.

Sea Hunt Video · Post by **Sea Hunt Video** » Jun 30th, '11, 16:02

Cap'n Bob:

I scarfed in two separate sections - one on the toe rail; one on the rub rail on my Cape Dory Typhoon Weekender. I used Boatlife Life-Calk Sealant for both applications. It worked very well. I did add some "teak dust" to the Life-Calk to more accurately match the teak rails. I also used Life-Calk when I "bedded" the screw holes and bungs.

RMeigel · Post by **RMeigel** » Jun 30th, '11, 16:22

I did not read your original post carefully enough - you specifically asked whether 3M 4200 was appropriate. I would say not. You don't need the adhesive properties for the two applications you cite - you need caulk properties. Removing the coaming board after applying 3M 4200 if you ever want to do it will complicate the removal effort.

I use life caulk for the spaces relating to the companionway, Dolphinite for the coaming boards.

Robin Meigel
s/v Pacem
1979 CD 27

Markst95 · Post by **Markst95** » Jun 30th, '11, 22:17

If the joint will be exposed to sun the 4200 would also discolor. 4000UV might work but still might be too strong a joint.

rperrone · Post by **rperrone** » Jul 5th, '11, 13:57

Thanks all. I am going with the life caulk. The blog link was good.

The Cape Dory Board

Sealing joints between teak coming bds and deck

Sealing joints between teak coming bds and deck

seal only the top

Sealants

Sealing Coamings - Or Not?

Sage?

Dolphinite Bedding Compound

3M 4200