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Old 28-07-2006, 16:09   #1
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Caulking the Chainplate ThruDeck?

While I'm repairing some bulkhead damage from a long seeping leak...I'm looking at the options for resealing it better.

This chainplate is a piece of aluminum bar stock about 14" long, 2" wide and 10mm thick bolted to a bulkhead (which is tabbed to the hull and furniture) and exiting the deck through one slot about 2" x 3/8". There's a small stainless trim plate that screws down over this, in theory compressing the sealant around the chainplate as it screws down, in practice not much more than cosmetic. And then one turnbuckle holding one shroud into the top, a conventional setup.

Except, the deck apparently works enough so that there has been a persistant leak. So I'm wondering what the best sealant for this is. Something intended to be tenacious, permanent, and elastic? Like Boatlife or 4200? Or maybe something old fashioned and low tech, like bees wax, which will reseal and reflow every time we get a real hot day, and can be easily repacked if it seeps out the bottom.

The more I think about high tech sealants just not quite doing their job...the more I'm thinking about low tech.

What is everybody else using for this?

I'm also thinking of notching away the top of the bulkhead just below the penetration in the deck, in the belief that if there's a small notch, any moisture that gets in, can easily roll out instead of hiding and keeping it damp. (The new top strip will be ipe, fairly resistant to start with.)
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Old 28-07-2006, 19:59   #2
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I use Life Caulk LIQUID. (Or is it called Life Seal LIQUID, I forgot, at any rate most marine stores don't sell it anymore so I had to order it lately)

Thin stuff, it flows down on the cracks around the chainplates and seals for a while.

As the rig/deck/hull moves ya have to re-seal the chain plates every 6 to 12 months.

If ye have old stuff in there, remove it all and put regualr caulk in.
I have used 101, 5200, 4200, etc..That is all fine for primary, but after a while ya get small leaks. That is when ya pour in a small amount of the liquid stuff without removing the primary...Like buying time.

To do a proper job, remove the chain plates, clean the area, etc. Then go with 5200...Can't do that every year however.

Depends how much ya sail and how much yer rig moves around.
To re-seal is normal operation on my CSY 33 however.
After a heavy rain I always go down and run my fingers along the chain plates. If there is a drop of water, I schedule a re-seal...Using a heat-gun to warm the plate and remove water, also using acetone to clean, then pour the stuff down on the cracks, let it sit for a while, then re-attach the little SS plates on top..Good to go for another 6 to 12 months.

Pretty low tech operation...
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Old 29-07-2006, 04:34   #3
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A bedding/sealant for a dynamic joint (such as a chainplate deck penetration) requires both tenacious adhesion, and high flexibility (elasticity), such as 3-M #5200 or Sika #292 - both Polyurethane structural adhesives.

Products such as Polysulfides, Wax, or “Duct Seal” (a butyl rubber compound) have been used (as gaskets) in static applications, such as sealing (screwed) teak decks & (bolted) hull-deck joints; but will not seal a moving gap.

Of course, a well engineered, installed, and tuned rig shouldn’t move all that much.
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Old 29-07-2006, 06:45   #4
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Of course, a well engineered, installed, and tuned rig shouldn’t move all that much.
No it should not if ya never sail the boat....
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Old 29-07-2006, 09:47   #5
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I always use a sealant which I can remove with pocket knife because I believe this is a job which requires doing & re-doing on a regular basis, like, every two or three years regardless of how much or how little use / abuse you ask of your vessel.

I've never found a chainplate which will not begin to leak eventually - except those mounted to the outside of the hull.

Furthermore - while you're at it, I believe it is prudent to take it one more step and occasionally pull the chainplates for inspection.

Chainplate failures probably account for most dis-mastings and chainplates often fail where they pass thru the deck.

It's a good idea to keep them dry and inspect them on a regular basis.

Kirk
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Old 29-07-2006, 10:05   #6
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I believe it is prudent to take it one more step and occasionally pull the chainplates for inspection.
Yeah good idea, but if ya have gone to all the work of taking the chainplate out, ya might as well replace it, especially if the plate is more than 15 years old.

I R&R all 9 chainplates on my boat 3 years ago. The cost from the machine shop came to $750.00 including 3 backing plates.

Another few hundred for electro-polishing, new bolts, parts, caulk, etc.

When installing the new plates I used 101 sealant, I should have used 5200 instead.
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Old 29-07-2006, 11:40   #7
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Gord-
"Of course, a well engineered, installed, and tuned rig shouldn’t move all that much. " It doesn't, but I suspect one of the days in 6-8 seas with 40+ knots might have, ah, exceeded the typical movement of the deck sealant on a 28' boat. If the sealant is the only thing that got bent out of shape, its hard to complain.

Sounds like 4200 is the way to go, 3M says that is more flexible than 5200 and flex is really going to be the key to longevity here.

I saw a British 30-odd footer built with the North Seas in mind (I have a blank on the make) and recalled looking at the chainplates as being odd British engineering....plate with ring fitting above and below deck, four bolts sandwiching them together, and a stainless ROD extending down to a keel member belowdecks, instead of the usual chainplate into the hull. I thought it was odd at the time but realize that deck transition would be a nice robust way to prevent leaks!
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Old 29-07-2006, 13:12   #8
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metal adhesion

This question keeps coming up over and again. Sikaflex makes a primer specific for the adhesion of the calk to the metal. There is no reason to expect adhesives to adhere to most metals without a primer.

The next problem is to create sufficient linear distance between the metal and the surrounding material to which the adhesive is to occupy. Note the worst "rattling" conditions under which the chainplates (or whatever the metal is used for) for the amount of linear excursion made. The gap must be more than 50% of the excursion (compression and expansion) made by the metal movement else the adhesive will fail. Mere compression by a surrounding plate is not sufficient without meeting these requirements.

I used to have trouble with chainplates until I applied the above and afterward did NOT have to re-calk the plates. Sikaflex (and others) have very specific instructions regarding this application..you have to seek it out and read it (this info is not on entirely on the tube of calk).
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Old 29-07-2006, 13:17   #9
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Aloha Rick,
Thanks for that. Very good advice!!
JohnL
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Old 29-07-2006, 13:20   #10
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Thanks, Rick. Never knew there was metal primer for caulk.

Off to see the wizard.

[and back]

The wizard still has pages "under construction" but Jamestown Distributors has more info on their site. Looks like the primer will be $12-40 for a bottle plus maybe another ten bucks for the sikaflex and tne more for shipping...Ouch, a $50 "goo" job!

Not that it isn't worth the money, but I can see why doing it right hasn't been very popular, compared to trying to use a buck's worth of something else form a tube.

For $50 I could install a hawse pipe and a lot of beeswax.<G>
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Old 30-07-2006, 02:49   #11
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A well designed chainplate should accept cycling loads without moving.

The key is to have the shroud or stay, and the entire chainplate assembly* exactly in alignment.
You can expect recurring troubles, any time you see a (factory) bent chainplate, or when the turnbuckle toggle is used to change direction (even slightly).

* Including the shroud/stay turnbuckle, thru-deck penetration, and structural attachment.

Another common design error is to penetrate the deck at a low or flat spot, that allows water to accumulate above the penetration.
The penetration should occur on a sloped* portion of deck, and preferably through a raised pad.
* Minimum of 2% (1/4" per foot) slope outboard.
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Old 30-07-2006, 08:38   #12
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stupid ? time

On some models the chain plates are exposed and on the outside of the hull, is there a similar problem that this causes? I have been looking at boats for years, (window wishing) and on several models the chain plates are external, I hate to high jack the thread but this is perplexing me.

On another Note: Gordmay, are you the aruthor of weather basics in GOB mag a few months back?
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Old 30-07-2006, 10:54   #13
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I still thinkj the best way to go if you are re-fitting chainplates is carbon fiber and foam with astainless insert for the toggle. Vacuum infuse the chainplate assy. to the hull/bulkhead and deck. Of course it should be engineered properly but it should do away with chainplate leaks for all time.

http://members.cox.net/building.galene/Chainplates.html

http://www.fram.nl/workshop/floats/floats.htm

hth, Deep.
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Old 30-07-2006, 11:34   #14
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Aloha Pun Pun,
External chainplates are extremely effective and have fewer leaks than the new internal chainplate systems of modern boats. You can also visual inspect them each time you go aboard. The reason, in my opinion, that they lost favor was because of their look and they might slow you down 1/100th of a knot if you are sailing with your rail down. Also because many boats increased their beam to the point where external chainplates would prevent a 150 genoa from being sheeted in tight on the outside of the shrouds.
If and when I change my chainplates they will become external.
Kind Regards, --JohnL--
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Old 30-07-2006, 11:51   #15
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I sailed years ago, learned on Lake Erie out of Vermillion OH, i am slowly working my way back, i have been on the dark side due to kids and wife. Well i am working at it and my wife is getting a little pissy with me when i keep showing her ads for boats adn places. She mentions one day that if she/we were to have a boat she wanted a "Capt Ron" boat, cool no prob. well it seems that every one she points out is beyond reach for me, but i will continue to work at it, but she seem to like the ones that have external chain plates, not on purpose, just the style for a lot of the "pirate" style boats that she seems to like. so it got me to thinking.
thanks for the reply.
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