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-   -   Embedded Chain plate maint/replacement (http://www.sailnet.com/forums/gear-maintenance/104772-embedded-chain-plate-maint-replacement.html)

chucklesR 10-16-2013 09:52 AM

Embedded Chain plate maint/replacement
 
I promised in this thread to start a new thread on the steps going forward.
http://www.sailnet.com/forums/gear-m...te-impact.html
This is my attempt at doing so.

Last night I pulled the joinery off and took a look at what I'd be needing to do to replace the chain plates.
Just a reminder - 1987 Irwin 38 CC MkII, chain plates embedded in the fiberglass, the tab with the pin hole (for the shroud) goes through a 2 inch thick toe/cap rail.
Here's the overall view:
http://i273.photobucket.com/albums/j...ps7cea17a9.jpg

The issue that spring boarded this:
http://i273.photobucket.com/albums/j...psd226cf54.jpg

That area from the outside on a FLIR image
http://i273.photobucket.com/albums/j...psf1361e9f.jpg
That area from the inside on a FLIR
http://i273.photobucket.com/albums/j...ps6cb92591.jpg
That area eyeball view, obvious long term water leak (previous owner).
http://i273.photobucket.com/albums/j...pse4cb9300.jpg

Okay, here's the big one. That area - no wood or joinery over it. Raw hull.
http://i273.photobucket.com/albums/j...ps5988b8dd.jpg

What you are seeing is two of the three chain plates (the forward one is on the other side of the bulkhead). The chain plates have two horizontal 'tabs' - like an inverted orthodox cross. I do not know how they are joined, no bolts are obvious so I assume a weld.
The obvious dirt is from long standing wet/rot over the years. I had no leaks at all until I removed the jelly fish/snot over the chain plate covers while doing the teak rails. It is all obviously years old.
Between the two horizontal tabs of the plates are some obviously well caulked screw pointy ends - they are what is holding the 2 inch thick, 3 inch wide rub rail on.

There is a heavy glass strip at the bottom of the plates, this folds horizontal over where the coring obviously starts (as well as the gel coat).
At the top there is a gel coat cover strip, up under that looks like this.
http://i273.photobucket.com/albums/j...psd8a60cb2.jpg

Those screws are bunged toe rail/cap rail, stanchion bases etc, going through the bases, teak, and folded 'shoebox' lips of the deck/hull.

Here's the underside showing a plate -
http://i273.photobucket.com/albums/j...ps4745d7d7.jpg


That's enough for now.

Faster 10-16-2013 10:30 AM

Re: Embedded Chain plate maint/replacement
 
This is going to be some job.. I expect you'll need to get to the opposite side as well at some point?

Once you get the glass off the inside I suppose you're hoping to pull the chainplates out from inside? or are you going to have to cut them out?

I expect you'll find the external crazing is from corrosion swelling on the plates.

davidpm 10-16-2013 10:50 AM

Re: Embedded Chain plate maint/replacement
 
I'm confused, how are the chain plates fastened?
They can't just be glassed to the hull and that is all, can it?

Is their any chance that they keep going down and attach to something below the seat. I can't tell from the picture if they stop or keep going.

I notice that they are in the middle of a span not at a bulkhead.
That means that the compression force has to be handled by the deck, yes?

Is that a nut at the bottom end of the forward chain plate?

Nice pictures, thanks for that!!!

deltaten 10-16-2013 11:36 AM

Re: Embedded Chain plate maint/replacement
 
Oh, Man! Looks like a nasty bit of work ahead!? Appears to be a glassed -in arrangement to me.
Best of luck to ya :D

StormBay 10-16-2013 12:02 PM

Re: Embedded Chain plate maint/replacement
 
I see two, how is access to the forward most plates (forward lowers I'm assuming)

Quote:

Originally Posted by davidpm (Post 1105723)
I'm confused, how are the chain plates fastened?
They can't just be glassed to the hull and that is all, can it?

These Irwin's have chainplates that are yes, simply glassed in. Its not that uncommon. Their are quite a few different boat builders that fastened chainplates this way on at least some of there models. Allied Luders 33, Hans Christian 33, Endurance 35 are just a few that come to mind.

Maine Sail 10-16-2013 12:37 PM

Re: Embedded Chain plate maint/replacement
 
Quote:

Originally Posted by chucklesR (Post 1105689)

There is a heavy glass strip at the bottom of the plates, this folds horizontal over where the coring obviously starts (as well as the gel coat).
At the top there is a gel coat cover strip, up under that looks like this.
http://i273.photobucket.com/albums/j...psd8a60cb2.jpg

Those screws are bunged toe rail/cap rail, stanchion bases etc, going through the bases, teak, and folded 'shoebox' lips of the deck/hull.

Chuck,

While you're in there you may want to add some through bolts to the hull/deck joint as opposed to just screw & glue....

BubbleheadMd 10-16-2013 01:18 PM

Re: Embedded Chain plate maint/replacement
 
Quote:

Originally Posted by StormBay (Post 1105780)
I see two, how is access to the forward most plates (forward lowers I'm assuming)


These Irwin's have chainplates that are yes, simply glassed in. Its not that uncommon. Their are quite a few different boat builders that fastened chainplates this way on at least some of there models. Allied Luders 33, Hans Christian 33, Endurance 35 are just a few that come to mind.

For the life of me, I cannot understand why a person would replicate this method instead of simply bolting them to the hull with suitable reinforcement.

chucklesR 10-16-2013 01:25 PM

Re: Embedded Chain plate maint/replacement
 
David,

The nut at the bottom of the forward (actually the center) plate is used to fasten a ground wire, it goes from there to the keel.

The plates stop at the heavy glass strip, they do not go anywhere else.

I'm not an engineer, I don't know where the compression is going - I thought it was to the keel, the mast is deck stepped with a post directly under the mast that transfers the compression to at 3/4 plate 2 inches above the (encapsulated) keel.


Maine Sail, you betcha - some of those screws have got to be replaced by bolts, probably all of them that are for stanchions and jib tracks - if I can get to the bottoms.


I have to get tarps, plastic, vacuums, tyvek suits and all that. Then it's off to fiberglass dust hades for a couple weeks.

I'll shoot some pics on the way.

overbored 10-16-2013 01:47 PM

Re: Embedded Chain plate maint/replacement
 
not sure what you worried about where the compression is going. the mast is in compression to the keel. the chainplates are in tension. fiberglass is very strong in tension. get a Fein saw for cutting away the glass. very little dust and the best tool for fiberglass work. worth the money.
FEIN Multimaster Oscillating Multi-Tool Kit-FMM 250 Start Q at The Home Depot

davidpm 10-16-2013 02:16 PM

Re: Embedded Chain plate maint/replacement
 
Quote:

Originally Posted by overbored (Post 1105848)
not sure what you worried about where the compression is going. the mast is in compression to the keel. the chainplates are in tension. fiberglass is very strong in tension. get a Fein saw for cutting away the glass. very little dust and the best tool for fiberglass work. worth the money.
FEIN Multimaster Oscillating Multi-Tool Kit-FMM 250 Start Q at The Home Depot

It is obviously OK as it has lasted a long time on a lot of different boats. I'm just trying to understand the loads.
The mast is pushing down that makes sense.
The chain-plates are pulling up.
Some portion of the load however is attempting to make the boat narrower.
I see a lot of boats that have the chain plates connected to a bulkhead.
The bulkhead is tabbed into the hull distributing the load.
The bulkhead often has a small beam that goes across the whole boat again distributing the load.

In this case the load attempting to make the boat narrower has to be taken by the deck.

I'm not saying it is a problem unless of course you had a soft deck.

I guess I find it hard to believe that a bandage of glass over the chain-plate on the hull is all their is to it.
Is it possible they are relying in part on 5200?
Does polyester resin stick that well to SS?

Did they do some tricks like put some holes in the stainless so the resin would form keys?

What I'm saying is that a SS bar bolted to a bulkhead makes sense to me. It is obviously strong.

This kind of construction has stood the test of time so must be pretty good, I'm just trying to understand it.


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