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  #21  
Old 07-03-2010
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Quote:
Originally Posted by mitiempo View Post
If you want to take a boat like yours that is built for coastal at most to Hawaii the strongest solution would be to glass the bulkhead in and attach the chainplates to them or place the chainplates outboard on the hull and lose a bit of pointing ability. Nothing else you can do will be as strong.
I appreciate Your input on this so please correct me if i'm off but Why is attaching them outboard on the hull different from the cabin top with a wire strut attached to the molded interior(where the bulkhead was attached) or to what the compression post sits on. I think the cabin top is the same thickness as the hull, being built in the late sixties when epoxy was cheaper and they didnt know how thick or thick to make them, I think its the previous
owner adding wood and glassing on top too. if the deck to hull joints are good. Have you heard of George Benson he cruises all around in a rebuilt Coronado 25. what about contessa 26
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George Benson? I thought he was a jazz musician.

They didn't use epoxy, but polyester for your hull and deck, as with most boats even today.
The Contessa 26 is in my and many others opinion a better built boat. But its chainplates are bolted to knees that are heavily glassed to the hull, a very good solution if there are no bulkheads in the correct location. This could be done but will require good glasswork. Pic of Contessa chainplates below.

I doubt your cabin top is as thick as the hull.
If the chainplates are attached to a bulkhead, even one not glassed in, it still spreads the loads around a bit and the bulkhead is not likely to pull through the cabin top and deck. Especially as they were originally also bolted through the athwartships beam under the deck. Glassed bulkhead is of course better.
The hull type of attachment is in shear. The hull is also the strongest part of the boat. The cabintop for the most part is flat and there is not much to stop the plates from either pulling through, distorting the cabintop, or putting a lot of stress on the hull/deck joint.
How are you planning to attach the strut? And to which part of the boat as the liner isn't a good attachment point? The original chainplates in a Coronado are well attached for the type of sailing the boat is designed for. 2nd pic.
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Replacing bulkhead bolted chainplates with deck bolted with a wire strut-contessa2.jpg   Replacing bulkhead bolted chainplates with deck bolted with a wire strut-coronado.jpg  
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Quote:
Originally Posted by mitiempo View Post
George Benson? I thought he was a jazz musician.

They didn't use epoxy, but polyester for your hull and deck, as with most boats even today.
The Contessa 26 is in my and many others opinion a better built boat. But its chainplates are bolted to knees that are heavily glassed to the hull, a very good solution if there are no bulkheads in the correct location. This could be done but will require good glasswork. Pic of Contessa chainplates below.

I doubt your cabin top is as thick as the hull.
If the chainplates are attached to a bulkhead, even one not glassed in, it still spreads the loads around a bit and the bulkhead is not likely to pull through the cabin top and deck. Especially as they were originally also bolted through the athwartships beam under the deck. Glassed bulkhead is of course better.
The hull type of attachment is in shear. The hull is also the strongest part of the boat. The cabintop for the most part is flat and there is not much to stop the plates from either pulling through, distorting the cabintop, or putting a lot of stress on the hull/deck joint.
How are you planning to attach the strut? And to which part of the boat as the liner isn't a good attachment point? The original chainplates in a Coronado are well attached for the type of sailing the boat is designed for. 2nd pic.
They referred to him a couple times in latitude 38.
My boat doesnt have that athwartships beam under the deck that supports the mast on normal coronados, just a 1/2 inch board screwed into the bulkheads and nothing else. The mast is supported by a aluminum compression post. What about to whatever the compression post sits on?
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Replacing bulkhead bolted chainplates with deck bolted with a wire strut-dsc00912.jpg   Replacing bulkhead bolted chainplates with deck bolted with a wire strut-dsc00937.jpg  
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The compression post is sitting on the cabin sole. I guess there is a structure under the sole that goes to the bottom of the hull on top of the keel. How would you transfer the upwards load of the chainplates to that?
I think the best way to do that is to use the bulkhead. I would replace the beam on the side of the bulkhead opposite the compression post and more or less duplicate the original design. Or I would move them outboard a few inches and use the hull itself. Bolt the chainplates through the hull afer first beefing up the area by glassing, with epoxy and biaxial cloth, a thick pad on the hull inside to spread the load. The pad should probably extend about 18" down from the hull/deck join and a ways fore and aft. This will transfer the loads to a much wider area.
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Quote:
Originally Posted by mitiempo View Post
The compression post is sitting on the cabin sole. I guess there is a structure under the sole that goes to the bottom of the hull on top of the keel. How would you transfer the upwards load of the chainplates to that?
I think the best way to do that is to use the bulkhead. I would replace the beam on the side of the bulkhead opposite the compression post and more or less duplicate the original design. Or I would move them outboard a few inches and use the hull itself. Bolt the chainplates through the hull afer first beefing up the area by glassing, with epoxy and biaxial cloth, a thick pad on the hull inside to spread the load. The pad should probably extend about 18" down from the hull/deck join and a ways fore and aft. This will transfer the loads to a much wider area.
whats a good way to repair the bulkhead without replacing the entire piece of ply. Someone took the chainplate out of the original holes and moved it over a inch and bolted it again, I want it in its original spot. I don't see or feel any rot when i prod it with a screw driver in the original holes and its not laminating. I'm going to sand it down and I was thinking I could epoxy both sets of holes and build up a epoxy pad where the chainplate would go.
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That should work. You could also add a doubler on the other side of the bulkhead, epoxied to the bulkhead for added strength. It will have to be on the other side as if in the main cabin it would cause the chainplate to be moved aft by its thickness.
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Quote:
Originally Posted by mitiempo View Post
That should work. You could also add a doubler on the other side of the bulkhead, epoxied to the bulkhead for added strength. It will have to be on the other side as if in the main cabin it would cause the chainplate to be moved aft by its thickness.
those pieces of wood in between the bulkhead and the chainplate in the picture arent supposed to be there the other owner added them and cut a new hole in the deck for the chainplate because he raised it of the bulkhead. I want it back against the bulkhead though the original hole.
what about sleeves in the bulkhead that are a little shorter than the bulkhead thickness, so when they are tightened down they compress the wood until they hit the sleeve? nilock bolts too.
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I would repair the holes with thickened epoxy and redrill for the bolts after it sets. There should be a backing plate and not just washers on the opposite side of the bulkhead to spread the load. Are the chainplates on the forward or aft side of the bulkhead?
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Originally Posted by mitiempo View Post
I would repair the holes with thickened epoxy and redrill for the bolts after it sets. There should be a backing plate and not just washers on the opposite side of the bulkhead to spread the load. Are the chainplates on the forward or aft side of the bulkhead?
forward of the bulkhead. If I went with west systems which hardener, thickener, and resin would be best suited for it?
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Hardener either 205 or 206 which will give you more working time. Brush the holes with the liquid epoxy before mixing the colloidal silica in until it is about as thick as peanut butter. Place tape like duct tape over the holes on one side. Fill the holes with the thickened epoxy and tape over the remaining side until it is set. This will prevent sagging. I sometimes tape a piece of plastic over holes as the epoxy doesn't stick to it and when set it will leave a finish that requires little sanding.
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