Rebedding troublesome chainplates

tartan30cirrus · Post by **tartan30cirrus** » Wed May 25, 2005 5:56 pm

Perhaps it was due to the large seas and the incredible swaying at the mooring, but I have another set of very leaky chainplates and they were just rebed! My question is what other methods can I use to ensure a good seal.

Here is the background: Tartan 30 plates are inboard of the toerail and stick through the deck. Two slots in the deck allow the plates to come through. About 1/8" to 1/4" gap around the plates allows a bed of sealant to seal the deck and trim plates go over the chain plates and are glued down to the deck with the caulk (I use 4200). Last year I back filled the slots with epoxy and rebed and had absolutely no leakage. Today I discovered inches of water in the chain plate locker. (With the epoxy backfill at least I can be sure that most of the water is not soaking the core.)

My theory is that when the boat is rigged up the forward chainplates bends a bit (maybe 1/32-1/16") under the tension and the caulk seal is broken with the chain plate...the plate pulls away from the sealant...a slight crack lets in a lot of water!

My question is...does it make more sense to recaulk the chainplates when the boat is rigged so the sealant cures with the chainplates in their rigged position. I was hoping to not have to rebed the plates every year. What else can I do to ensure that the plates are sealed? I am careful to clean surfaces and pack a lot of caulk into the gap...seems like I need a way to get the 4200 to stick better to the SS chainplate. I don't want to use 5200 but I am tempted. (wouldn't the "Debond" 5200 remover help?)

Thanks.

Cheers.

Besides I have other work to do now...stay tuned for storm damage pics.

Post by **Tim** » Wed May 25, 2005 6:20 pm

Chainplates are a constant leaking pain. More leaks start at chainplates than almost anywhere. It's that big slot, coupled with a very dynamic load, that makes them so problematic.

As least you've sealed the deck openings with epoxy, but it's still annoying to have leaks. Do you have trim plates around the chainplates on your deck? The chainplate itself should be well bedded, of course, but big gobs of sealant (no, do not use 5200--it will still fail) beneath a deck plate is the best way to keep water out. This is the one place that I do not clean up the squeezeout; I leave the gross gobs of gunk there as an additional barrier. My covers are just homemade wooden thingies.

A30_John · Post by **A30_John** » Wed May 25, 2005 8:29 pm

I do what Tim does re: squeeze out... i.e. I leave it there. Also, what kind of sealant do you use? I used LifeSeal on my previous boat and found that stuff to be extremely tenatious.

Post by **Tim** » Thu May 26, 2005 6:51 am

I used 3M 101, polysulfide, which I believe is the same as Lifeseal...or is it the same as Lifecaulk?

I generally like 101, other than the fact that it turns brown where exposed.

tartan30cirrus · Post by **tartan30cirrus** » Thu May 26, 2005 9:28 am

I use 4200... which works fine...last year not a drop came through and I felt very successful in my work...but it is already bringing in a lot of water so either my method was not sufficient (may have rushed the job) and/or the constant mast pumping in the waves at the mooring broke the seal...I have to imagine the boat was flexing a little bit more than normal in these seas for days on end...closer inspection when weather improves will inform the situation I am sure.

Does 3M 101 stick better than 4200...the adhesion is key for my situation.

Cheers.

A30_John · Post by **A30_John** » Thu May 26, 2005 1:13 pm

I think 101 is the equivalent of LifeCalk.

If I've got my facts straight, LifeSeal is a blend of polysulfide and silicon sealants. It was designed for sealing plastic/lexan windows, but is is approved for use above and below the waterline. I like it because it has very good flexibility and the bond is excellent. I've used it on chainplates and all sorts of deck hardeware with good results.

I used LifeCalk on the new cockpit hatch just to see how it works. So far so good.

tartan30cirrus · Post by **tartan30cirrus** » Thu May 26, 2005 4:37 pm

A30_John wrote:I think 101 is the equivalent of LifeCalk.

If I've got my facts straight, LifeSeal is a blend of polysulfide and silicon sealants.

101 is Lifecaulk.

Life seal is a silicone/polyurethane hybrid and I like it a lot too although it has the silicone characteristics that drives Tim crazy!

Cheers,
Clint

Figment · Post by **Figment** » Thu May 26, 2005 5:11 pm

tartan30cirrus wrote:Does 3M 101 stick better than 4200...the adhesion is key for my situation.

4200, as a polyurethane, will adhere more tenaciously than a polysulphide like 101, but that's not the whole ballgame. The purpose of the chainplate sealant isn't to adhere two objects together (prevent them from moving independently), the purpose is to provide a flexible seal despite that unavoidable independent movement.
In this application, flexibility trumps adhesion, which is why you might give a polysulphide like 101 a try in lieu of the adhesive-oriented polyurethanes. I've known a few boats that had to go with butyl to seal pesky chainplate leaks because they "work" back and forth so much.

Rough way to start a season!