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-   -   Chainplate advice needed (http://www.sailnet.com/forums/gear-maintenance/99606-chainplate-advice-needed.html)

meboater 05-17-2013 08:45 PM

Chainplate advice needed
 
I have read the sticky on butyl tape, as well as a bunch of other posts.
This chainplate seems a bit unusual, and I would appreciate any knowledgeable input.

The plates run perpendicular through the deck, then mount on a pillar of sorts inside. There is no structural hardware through the deck or hull.

They pass through this slotted plate, which is fastened by machine screws.
https://lh4.googleusercontent.com/-y...517_132258.jpg

Un the inside of the cabin, they go through a hollow pillar, with reasonable access to the inside. They are fastened to the inside of the boat with carriage bolts and backed by washers.
https://lh3.googleusercontent.com/-V...517_131445.jpg

The inside of the boat against which the plates are fastened, is quite discolored and gunky. This is fiberglass.
https://lh6.googleusercontent.com/-x...517_132057.jpg

The inside of the plates is also gunky.
https://lh5.googleusercontent.com/-Z...132258-001.jpg

So- I have three surfaces to clean.
1- Deck
2- Cabin liner.
3-Insides of slotted plate and chainplate.

What chemicals, if any, are ok on these surfaces?
What tools can I use? how abrasive is ok on these surfaces?

For some reason the bolts on the inside of the boat were caulked. Any reason to redo that?

Any input or thoughts are appreciated.

CalebD 05-17-2013 09:40 PM

Re: Chainplate advice needed
 
It seems pretty obvious that water has gotten in behind your chain plate at some point. The discoloration points to rust, or worse perhaps water leaching out of whatever is behind the knee wall your chain plate is mounted to.
Looks like you have an access port to look into the knee wall. What do you find in there? Boat builders often hide pieces of wood in places like this (where you can't see them). If there is wood in there it is possible that it has gotten wet and is in some state of decay and may have leaked moisture out the bolt holes behind the plate that has discolored the surfaces. If there is wood inside there it may need replacing.

For cleaning it up: acetone, de-natured alcohol etc. Light sanding with fine grit paper etc.

Re-bed it all with Butyl tape as you seem to be planning to do.

What boat make/model is it?

paul323 05-17-2013 09:43 PM

Re: Chainplate advice needed
 
Polish the chainplates, and inspect very closely for cracks...experts wipe a dye over them, which can highlight any imperfections. I am not sure where it can be obtained. *Any* doubts about the chainplate integrity, replace them!

meboater 05-17-2013 10:32 PM

Re: Chainplate advice needed
 
Quote:

Originally Posted by CalebD (Post 1032027)
It seems pretty obvious that water has gotten in behind your chain plate at some point. The discoloration points to rust, or worse perhaps water leaching out of whatever is behind the knee wall your chain plate is mounted to.
Looks like you have an access port to look into the knee wall. What do you find in there? Boat builders often hide pieces of wood in places like this (where you can't see them). If there is wood in there it is possible that it has gotten wet and is in some state of decay and may have leaked moisture out the bolt holes behind the plate that has discolored the surfaces. If there is wood inside there it may need replacing.

For cleaning it up: acetone, de-natured alcohol etc. Light sanding with fine grit paper etc.

Re-bed it all with Butyl tape as you seem to be planning to do.

What boat make/model is it?

There is no wood or anything in there, and what I can see all looks good and clean.

As far as abrasives on stainless- How fine do I need to go? I often use something like this for projects:
http://ecx.images-amazon.com/images/...500_AA300_.jpg

Too abrasive?


Any thoughts on the glass? I have some cleaner that worked great on waterline browning which I'll try on the inside. I was thinking Goo Gone for the gunky stuff on the outside. Any other good chemicals or tools for cleaning glass?

meboater 05-18-2013 02:03 PM

Re: Chainplate advice needed
 
OK-
I got all my surfaces clean. I am planning to use a skinny drill bit in the slot in the deck to de goop it and give my sealant something to adhere to. I may even expand the slot a bit to allow sufficient sealant in the gap. I am also going to countersink the screw holes.



Follow up question:

https://lh3.googleusercontent.com/-V...517_131445.jpg

When these were installed- or re-installed- a layer of caulk/goop/sealant was used between the stainless and the interior boat surface. (unfortunately some of that bond was stronger than the gelcoat/glass bond) Is there any reason to use sealant in there? Or on the bolsts?

overbored 05-18-2013 02:30 PM

Re: Chainplate advice needed
 
not really any reason for sealant if there is no water to keep out. not sure which holes you are planning on countersinking. the deck plate is ok but do not countersink the chainplates. the countersink heads are not as strong in shear as the carriage bolts.

davidpm 05-18-2013 02:48 PM

Re: Chainplate advice needed
 
Considering the labor involve in taking the chain plates out then polishing them and reinstalling them you may want to think about replacement.

I remember one story where a guy took out his chain plates they looked perfect but were original so he decided to replace them. He gave the old chain plates to a friend at a machine shop to reuse the steel.
His friend called him a few months later and told him that when he put an old chain plate in a shear to cut it, it shattered. It looked perfect too.

So not only is corrosion a problem but work hardening too.
How lucky do you figure you are?

rhr1956 05-18-2013 03:08 PM

Re: Chainplate advice needed
 
Make sure and seal the chain plate cap real good. I put sealant in the slot around the chain plate, under the chain plate cap and after everything back together I put more on the top side of the cap where the chain plate comes up through the slot. With a wet finger used to finish the exposed sealant, it looks fine. Dry as a bone.

meboater 05-18-2013 05:35 PM

Re: Chainplate advice needed
 
Quote:

Originally Posted by davidpm (Post 1032262)
Considering the labor involve in taking the chain plates out then polishing them and reinstalling them you may want to think about replacement.

I remember one story where a guy took out his chain plates they looked perfect but were original so he decided to replace them. He gave the old chain plates to a friend at a machine shop to reuse the steel.
His friend called him a few months later and told him that when he put an old chain plate in a shear to cut it, it shattered. It looked perfect too.

So not only is corrosion a problem but work hardening too.
How lucky do you figure you are?

The boat is a 90's vintage boat, that seems to have not been heavily used. Removing the chainplates is probably an hour. Between my wife and I, we got everything clean in a few hours.

How lucky do I think I am? Of all the potential mishaps in my future, this one is fairly low on the list. For example, my forestay looks good, so I am not replacing it. This, despite that it is the only non-redundant bit holding the mast up.

asdf38 05-19-2013 10:25 AM

Re: Chainplate advice needed
 
I'm going through the exact same thing and my chainplates looked roughly similar. That is, a decent amount of visible surface corrosion but perhaps no deep corrosion. Regardless I think I'm getting new ones. I don't see a strong reason not too, it's just machined stainless won't be terribly expensive.

You could consider replacing the hardware too, I love McMaster.com for stainless hardware.

For sealant I'm considering butyl with life caulk over that so on the deck I won't have sticky butyl. Though I'm still unsure.

One thing not to do: seal from the inside. My PO did that and it helped cause significant core damage in the chainplate area - if water gets into the deck you want it to have a chance to get out again, and you want to know it was there. Never seal from the inside.


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