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Discussion Starter · #1 ·
I promised in this thread to start a new thread on the steps going forward.
http://www.sailnet.com/forums/gear-maintenance/104260-chain-plate-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:


The issue that spring boarded this:


That area from the outside on a FLIR image

That area from the inside on a FLIR

That area eyeball view, obvious long term water leak (previous owner).


Okay, here's the big one. That area - no wood or joinery over it. Raw hull.


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.


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 -


That's enough for now.
 

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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.
 

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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!!!
 

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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
 

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Jnoiur Mebemr
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I see two, how is access to the forward most plates (forward lowers I'm assuming)

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.
 

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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.


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....
 

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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.
 

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Discussion Starter · #8 ·
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.
 

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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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...Allied Luders 33, Hans Christian 33, Endurance 35 are just a few that come to mind.
Allied bolted the Luders 33 chain plates to wooden "knees" glassed to the hull and then glassed-over the entire thing.

Second the Fein for cutting over a zip-cut/angle grinder.
Second the Fein for cutting over a zip-cut/angle grinder.
I would also suggest a multi-tool, not necessarily Fein. I would recommend a Milwaukee which is cordless and comes with two batteries which I was amazed how they last - for a much lesser price (tool and blades). The important piece is the kind of blade, and I would suggest you get 2 or 3 of the half-circle shaped ones with many small teeth - they have worked very well for me to cut thru glass - use a back and forth motion with them. Have a vacuum going at the same time with the nozzle close to the tool and you'll remove the glass cleanly in no time at all.
 

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Jnoiur Mebemr
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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?
The chain plates in this one look like they have bars or rods welded to them, to form the upside down T shape that you see, which is than glassed into the hull. If the plates don't break they would have to rip out all of that glass before they pulled out the T shape bars and therefor don't have to rely on the bond between the fiberglass and the stainless. As SVTatia pointed out the Luders 33 use a different method of doing essentially the same thing (i.e. not relying on the bond between fiberglass and metal but rather fiberglass to fiberglass. Make sense?
 

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I would also suggest a multi-tool, not necessarily Fein. I would recommend a Milwaukee which is cordless and comes with two batteries which I was amazed how they last - for a much lesser price (tool and blades). The important piece is the kind of blade, and I would suggest you get 2 or 3 of the half-circle shaped ones with many small teeth - they have worked very well for me to cut thru glass - use a back and forth motion with them. Have a vacuum going at the same time with the nozzle close to the tool and you'll remove the glass cleanly in no time at all.
Yes the cheap tools work fine, but the cheap blades don't last at all. A couple of uses in soft wood and the "Workmate" (Loews house brand) brand blade was shot. Though the $35 Workmate brand tool works quite well. I have borrowed a Fein, and it seemed to operate a bit smoother, but did not work any better on my projects. And with all the fiberglass dust, that may just do in the tool anyway. The Harbor Freight multi tools seem to have it's fans as well.
 

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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.
It is a very strong way to attach chainplates if done properly. With a well built hull and deck there are no issues. It is not a bandaid of glass holding them in - the force is straight up pretty much for the uppers and inward slightly for the lowers. The chainplate's force is basically upwards and the overlap of the hull and deck (hopefully not just screwed together) places a good thickness of glass stopping upward movement. The Spencer 35 uses basically the same method except it is a bar that runs fore and aft and not as far down the hull and it has stood the test of time as well as long voyages by Hal Roth, Paul Lim and others.

But with modern knowledge of crevice corrosion it is a lousy way to attach the plates leaving any corrosion hidden from view. With chainplates being hard to seal over time moisture will eventually get in and corrosion will follow.
 

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So the next question is how to put it back together again so they can be inspected easily and/or replaced?

Bolting right through the hull is the obvious solution.
External is another obvious solution.

I doubt if most owners would be willing to change the look of the boat that much.
It really looks pretty and is out of the way coming out of the cap rail like it does.

Of course the argument could be made that they lasted over 30 years so put back together with epoxy instead of polyester and call it good for another 30 years.

If a better mounting is impossible maybe this is the right place for titanium regardless the cost.
 

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This kind of construction has stood the test of time so must be pretty good, I'm just trying to understand it.
Actually it hasn't. It stands the test of about 25 or so years and then presents a HUGE nasty problem to the owner at that time - keep following the thread to see how nasty. The worst part of it is that it precludes inspecting the chains for crevice corrosion.

It is a quick & cheap way to install chains, no other reason for it.
 

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Simplest solution is on the outside of the hull. Without a bulkhead in each plate's location there are no other options I can see except the original method. That was probably the reason it was done this way to start with - without knees which would have been in the way of interior cabinetry or bulkheads at the right place it allows placement anywhere the builder wanted.
 

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If a better mounting is impossible maybe this is the right place for titanium regardless the cost.
Wonder how bronze would survive installed this way for a few decades. Problem is that water will get in eventually.
 

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Once you cut out the chain plates I would be interested in how thick that bandage of glass is covering them?
 
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