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  #31  
Old 10-17-2013
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Re: Embedded Chain plate maint/replacement

davidpm's solution sounds awfully good. It sounds like it puts the stresses pretty much where they were before, without embedding parts that get wet above deck and without messing with the outside of the hull or taking up huge amounts of interior.
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  #32  
Old 10-17-2013
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Re: Embedded Chain plate maint/replacement

David's idea is interesting but would not be as strong as the original. Instead of the large chainplate glassed in solidly the vertical plate's strength would only be as good as the bolts used. If you are going to put 4 or 5 large bolts through the hull to make it strong enough you may as well install the plate outside for easier inspection. This will also eliminate the hole through the deck that exists currently.
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  #33  
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Re: Embedded Chain plate maint/replacement

With David's idea, I don't believe the bolts were going through the hull, just through the chainplate into the cross plates. Doesn't it pretty much always come down to the bolts? I guess it did with my last boat, a Pearson 28-2, where I believe the chainplates were fastened to a knee in the hull with 3 (I think) bolts.
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Old 10-18-2013
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Re: Embedded Chain plate maint/replacement

Quote:
Originally Posted by chucklesR View Post
FWIW I spent a lot of time discussing the plates and how to fix or re=-install with both Maine Sail and Jeff_H, neither of which is a lightweight when it comes to stuff like this.

Neither of them had knowledge of the shape of the plates prior to today - all I could tell them was that a horizontal band/tab was involved, but no through bolts etc.

Titanium is one of the the things I'm looking at, the could be thinner in all dimensions.
Science has moved on since 1987, I have a LOT more options than "drill through the existing and bolt new ones on the outside" - that's the first and last option according to the Irwin 'expert' - a Mr. Gene Gammon.
I prefer taking advice from someone that does not tell me to leave the possibly rusting old ones in place as backing plates.

I'm still thinking- I might go with a hybrid inner/outer.
I have to rebuild the 'furniture', i.e. book shelves, I do not have to rebuild them they way they were.
If you're going to replicate the original method, then titanium seems a good way to go.

AllThumbs had a good idea, about leaving weep holes. Not only would it prevent freeze damage, but it would also provide an indicator of trouble when you start seeing water stains.

People are also right when they point out that this system lasted 25 or 30 years. If you do it right, you'll probably never worry about it again in your lifetime.

I guess I kind of overreacted when I said to just bolt them to the hull.
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Re: Embedded Chain plate maint/replacement

Subscribing. This'll be interesting.

What about going ahead and drilling a couple small holes in the bottom of the glassed in area now just to see what happens?
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Re: Embedded Chain plate maint/replacement

Let's see if I can describe this well - I don't have a good drawing tool that is easy to use.

1) make some knees out of g-10 - laminate to a 1 inch thickness. Put them in - one per plate with epoxy, fillets and heavy glass (maybe CF, double layer). Smooth, fair, paint.
2) turn the plates 90 degrees, bolt through the knees, backed on the other side.
3) build joinery back where and how I like.

I'd have inspectable plates, be able to see any leaks and rectify and I 'think' just as strong. The knees would run from the deck to the core area, really don't need to be much more than the width of the plate as it's more about spreading the load - and that's on the fillets and fiber glass tabs and tapes.

BTW - let's call the discussion on 'it's on the bolts' pretty much done. The bolts can pretty much hold the entire weight separately - look up the tensile and sheer strengths.
The shrouds are rated about 9k SWL - bolts pretty much better than that.
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Re: Embedded Chain plate maint/replacement

Quote:
Originally Posted by mitiempo View Post
David's idea is interesting but would not be as strong as the original. Instead of the large chainplate glassed in solidly the vertical plate's strength would only be as good as the bolts used. If you are going to put 4 or 5 large bolts through the hull to make it strong enough you may as well install the plate outside for easier inspection. This will also eliminate the hole through the deck that exists currently.
At the risk of starting something I'm not prepared to finish.

This is a little like the difference between some anchors. Some are welded some are bolted. As long as the numbers work out from a strength point of view it probably don't matter.

All you have to do is make sure the bolts are about 10 times stronger than the piece of wire connected to the plate and I suspect it doesn't matter any more.


My idea was that the bolts thread into the vertical plate and do not go through the hull.

The width and thickness of the plate below the cap rail, it can be doubled for more thickness and/or wider for more room to space bolts, can be adjusted until the strength and the number of bolts is as strong as needed.
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Last edited by davidpm; 10-18-2013 at 12:26 PM.
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Re: Embedded Chain plate maint/replacement

Quote:
Originally Posted by chucklesR View Post
1) make some knees out of g-10 - laminate to a 1 inch thickness. Put them in - one per plate with epoxy, fillets and heavy glass (maybe CF, double layer). Smooth, fair, paint.
2) turn the plates 90 degrees, bolt through the knees, backed on the other side.
3) build joinery back where and how I like.

BTW - let's call the discussion on 'it's on the bolts' pretty much done. The bolts can pretty much hold the entire weight separately - look up the tensile and sheer strengths.
The shrouds are rated about 9k SWL - bolts pretty much better than that.
That would work strength wise but I was trying to save the guy the significant hassle of redoing the joinery.
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Re: Embedded Chain plate maint/replacement

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Originally Posted by Faster View Post
Second the Fein for cutting over a zip-cut/angle grinder.
All of them!

I'll also plug for Milwaukee. The M12 line has a lot of tools which have been indispensable for me on the boat - Multi-Tool (which also sands), Rotary Tool (Dremel) and compact right-angle drill in particular.

They all share batteries so when I'm upside down somewhere and one battery dies I can swap it with whatever is in the tool nearby. And I have have several tools on hand without several power cords.
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Re: Embedded Chain plate maint/replacement

Quote:
Originally Posted by chucklesR View Post
...
1) make some knees out of g-10 - laminate to a 1 inch thickness. Put them in - one per plate with epoxy, fillets and heavy glass (maybe CF, double layer). Smooth, fair, paint.
2) turn the plates 90 degrees, bolt through the knees, backed on the other side.
3) build joinery back where and how I like.

...
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.
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