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  #41  
Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

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Originally Posted by davidpm View Post
That would work strength wise but I was trying to save the guy the significant hassle of redoing the joinery.
Um, I'm the guy - and the joinery is already 'gone' even though I took it out in one piece I will not be reusing it.
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  #42  
Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

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Originally Posted by SVTatia View Post
That should work. When you laminate the knees, spread the fb widely to distribute the load. The trick will be to make the "twist" on the plate itself (weld?), as it needs to be facing athwartships at the deck level and fore and aft below deck to be bolted to the knee. And it will need to be inserted into place from below.
You then build the cabinetry around it with an inspection port.

I've got almost 2 inches of opening between the hull and the cap rail (inside the bulwark). I think I can just re-cut an awarthship slot in the toe rail. If not
I've got a machine shop that I think can do the twist hot and re-anneal it.


The 'hump' below is the encapsulated plate - all of that would be cut down/ground flush to hull - lots of room for a plate at 90 degrees to hull.
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  #43  
Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

I don't understand why the twist is necessary. The chainplates on my Pearson 28-2 with knees have no twist, the knees are U-shaped with clearance to access the bolt heads. I haven't looked my friend's Yankee 30 (which also uses knees) too closely but I think it worked the same way.

I do think that knees are the way to go.
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  #44  
Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

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Originally Posted by chucklesR View Post
Um, I'm the guy - and the joinery is already 'gone' even though I took it out in one piece I will not be reusing it.
If you are going to redo the wood anyway then your options are wide open.

The knee idea would be great and you might even be able to make it so the chain plates are completely visible inside the cabinet just like in many other boats.

I really like the way you take pictures. They really show what is going on.

Good luck with your project.

I'm sure you have good reason to replace the interior woodwork as I know you are very experienced.

Just as a warning to others though the replacement of interior joinery so it looks good and matches is often a much bigger job that it would seem at first blush.
It is one thing to do structural repairs where mostly strength is important.
It is quite another thing to do interior joinery where, fit and matching existing finish and utility are all important.

I would think that replacing the joinery on this project would probably be at least as much work and probably more work than the structural part.

But I'm a few miles away so you know best.
I was a cabinet maker in a past life and all I know it it always seems to take me a lot longer than I figured it should to do cabinet work on a boat.

If you change the orientation of the chain plates from for to aft to side to side you will have some cap rail repairs to do that will show, yes?

As you can see I'm very concerned about creating ancillary finish projects during the process of repairing a structural problem. I've been burned before.

A very classic case of this when someone replaces an engine and they have to cut into cabinetry to fit the new engine.
I've seen several of those jobs that just never looked right and it severely reduced the value of the boat.
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Last edited by davidpm; 10-18-2013 at 02:05 PM.
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Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

I don't understand the comments about twisting the chains to mount them on a knee - a knee is just a mini-bulkhead so the chains will mount athwartships just like they would if mounted to a bulkhead. The slots in the deck would have to be filled & recut to change the orientation.

A really skookum setup would angle the knees for lower shrouds to put the chains in line with the angle the shrouds form with the mast - angled aft for the forward lowers and forward for the aft lowers.

I still say the simplest method would be to clean up the area where they currently sit to get a smooth mounting surface and bolt them through the hull - virtually a direct replacement for the existing setup and only a few S/S carriage bolt heads showing on the outside. Just as easy to remove for inspection as any other bolted setup too.
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Last edited by SloopJonB; 10-18-2013 at 02:11 PM.
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Re: Embedded Chain plate maint/replacement

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Originally Posted by SloopJonB View Post
I still say the simplest method would be to clean up the area where they currently sit to get a smooth mounting surface and bolt them through the hull - virtually a direct replacement for the existing setup and only a few S/S carriage bolt heads showing on the outside. Just as easy to remove for inspection as any other bolted setup too.
That certainly sounds simple and would look OK for some people but fiberglass is brittle especially gel coat.
So exactly how much to you torque the bolts so the heads doesn't crack the gel coat. The obvious solution is to use a standard bolt with a washer. But now it doesn't look so good. Then the next option is a backing plate. The backing plate could come right up to under the cap and look ok for some folks but it is a different look for sure.

I'm pretty sure carriage bolts are best set into wood where it is expected that they will crush in a little as you tighten them.
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Re: Embedded Chain plate maint/replacement

Davidpm,

Not much I can't do with wood. I'm not a professional but I 'm a pretty fair amateur wood smith with both power and wood tools. I saved the old facing so I've got both ready at hand trim and bits for stain matching.

JonB - the 'twist' is because the plates are flush to the hull. Knees would by definition be perpendicular to the hull (at right angles). As I said in my response I'd probably just change the cap rail by re cutting a slot awarthship.
I'd repair the current slot with a dutchman, then cut the new.

Close up of the cap rail, just for entertainment purposes.

Before:


You can tell it's really 5 strips of teak. Anywhere it's joined it has a nice curved joint like it should be. This is with 1 coat of JD's Total Care, natural teak - no gloss / clear yet.


[IMG][/IMG]
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Re: Embedded Chain plate maint/replacement

Knees don't need to be built in a way that requires a twist. This photo isn't mine (and isn't a Pearson 28-2), but closely resembles how they are done on my boat:


The knees don't need to be that deep if space is a concern. They only need to come in far enough for you to get a wrench around the back side of them.

Edit: one thing that isn't clear from this photo is how you access the back of the chainplate. On my Pearson there are cutouts in the knees to access the nuts on the backside. I'll take photos when I'm next at my boat (likely this afternoon).
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Last edited by Alex W; 10-18-2013 at 03:32 PM.
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Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

I think through bolting would work. I doubt you could pull a carriage bolt head through the glass, and I expect you would use 2 or 3 on each chainplate. Also remember the stress is in shear, making it even more difficult to pull a carriage head through the hull.

Also, don't forget, at the mast the rig is usually fastened to a tang that is held on by 4 pop rivets. We get all anal about how the chainplates are fastened (and we should be) but it only needs to be stronger than the tang at the top.

No one has suggested just glassing in new plates. That's how it's been for 30 years, so no reason to think it's not adequate. Grind out the old ones, smooth everything with 30 grit on an angle grinder, and glass in new ones. On mine, I first filleted in the chainplate with thickened structural epoxy (after pushing the chainplate into a bed of same), then added 5 layers of 9 oz. cloth over them.

For sure you need to grind one out to have a look at what's going on. Can't really make any decisions until one is out.
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Re: Embedded Chain plate maint/replacement

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Originally Posted by SloopJonB View Post
I don't understand the comments about twisting the chains to mount them on a knee - a knee is just a mini-bulkhead so the chains will mount athwartships just like they would if mounted to a bulkhead. The slots in the deck would have to be filled & recut to change the orientation.

A really skookum setup would angle the knees for lower shrouds to put the chains in line with the angle the shrouds form with the mast - angled aft for the forward lowers and forward for the aft lowers....
A knee is not just a mini-bulkhead - its is an essential structural point that needs to be strong enough to support the whole rig!
Angled knees? Much easier said than done. But you hit it on the head by mentioning that the chain plates need to be set at the same angle as the two lowers, but only if they are oriented fore and aft. As you see, the original ones mounted athwartships don't need to be, thus if the plates are bolted to the knees, they need a weld or hot-formed to be aligned with the lowers angle --- now: how do you measure the angle that they should be at?
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