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Replacing bulkhead bolted chainplates with deck bolted with a wire strut

8K views 40 replies 4 participants last post by  MAnDaRIn 
#1 ·
My double chainplates are bolted to the bulkhead and have dry rott. previous owner moved it over a couple inches and raised it with teak boards and bolted thru again(see pic1and 2). I have removed the bulkhead and want to replace the chainplates with double deck bolted ones that connect to a wire strut attached to the hull(see 3 and 4 double with out that other attachment to the chainplate cover). Where can i buy this kind of chainplate?
 

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#2 ·
While most machine shops could make them for you, I wouldn't recommend doing that without consulting a marine architect. Your boat was designed to have its rig in a certain position and moving it may cause serious issues.

I'd point out that the bulkhead in question is clearly structural, and needs to be replaced before you can use the boat.

It would help if you said what kind of boat you had, since there may be a known fix for the boat that other owners have come up with.
 
#4 ·
While most machine shops could make them for you, I wouldn't recommend doing that without consulting a marine architect. Your boat was designed to have its rig in a certain position and moving it may cause serious issues.

I'd point out that the bulkhead in question is clearly structural, and needs to be replaced before you can use the boat.

It would help if you said what kind of boat you had, since there may be a known fix for the boat that other owners have come up with.
i know what happens when you move the chainplate around. I'm talking about putting it in the same place, same hole through the deck. bulkhead is not structural some previous owner glassed it in with polyester resin when i removed it most of the cloth wasn't stuck to the bulkhead.they aren't glassed in on other boats of the same make. before I had it hauled out I sailed thru a gail or two with out incident but they look to be pulling out from the look of the bolts angle. There is a aluminum vertical compression post that replaced the original horizontal wood one that rode on the bulkheads.
I know i can have someone fabricate them, I'm wondering any companies makes them or if get some that are made for another boat.
 
#3 ·
I agree with dog. While the chainplate in pics 3 & 4 looks good, the original method used on your boat is probably stronger with a solid bulkhead properly glassed in as it spreads the load over a wider area. Most manufacturers use a method like this because of its strength. Usually they only vary it when the accomodations don't allow it.
As dog said the bulkhead requires proper replacement regardless.
 
#7 ·
Manufacturers seldom use an off the shelf chainplate, most are custom for each model. You might be able to find one similar but probably not exactly what you want. The hole has to be the correct size for the toggle or turnbuckle your rig uses. A hole too large is a problem. What boat do you have? Maybe someone here could help more if we knew.
 
#9 ·
You're saying there isn't any specific brands of chainplates that people tend to favor like Harken or Schaefer. I thought maybe someone knew one, that is pretty much what I was asking. The holes being the correct size and thickness is a given. already asked the group for the boat but my rig is a custom job very different from the originals.
 
#8 ·
Well, I am guessing that the bulkhead is structural... it has to be if the chainplates are TIED TO IT. If the bulkhead isn't structural, they would never have tied the chainplates to it. :rolleyes:

Again, it would help if you said what kind of boat you had, since there may be a known fix for the boat that other owners have come up with.
 
#13 ·
The bulkhead attaches to the molded interior via screws at the bottom and screws to a headboard that is not glassed in, it runs to the other bulkhead and connects with screws. The headboard is kinda just wedged in and screwed to the bulkheads. I already said that most of the glassing wasn't stuck to the bulkhead like not glassed on(not done by the manufacturer). Ive been sailing it like that for a year on the bay, some times in heavy winds with no reefs. so basically the only thing keeping the rig up was bulkheads attached with screws being pulled tight against the cabin top. When you said the bulkhead needs to be replaced before i can use the boat did you mean that the bulkhead does more the hold the chainplate? because i pretty much explained that its not glassed in at all. When I un-stepped the mast both bulkheads and headboard could be move back and forth freely by definition(permanently fixed) It is NOT STRUCTURAL. :rolleyes: and originally(from the manufacturer) the chainplates were attached to the cabin top but someone beefed up the rig and decided to bolt new chainplates to the bulkheads, so you really jumped the gun on your I know everything and your a greenhorn speech, just because i just signed up on sailnet doesn't mean i don't know stem from stern only that i haven't owned a computer in a few years!!!:chainsaw
 
#10 · (Edited)
Schaefer makes chainplates but they are all basic stainless chainplates and not what you are after. Here's the link to their chainplate page.
Schaefer Marine Hardware - Product Catalog

Harken is a very innovative company. But chainplates are not really an innovative type of product. They do not make them. Not in my catalog or their online catalog. They are also boat specific so the market would not be worthwhile. The chainplates that come with the boat will last decades if not the life of the boat. Every boat design has different requirements and other than a straight bar type of chainplate which Schaefer has there probably isn't one available to fit your needs. Every rig has different angles and hole sizes and every deck design is different as far as angle is concerned.

Your best bet is to draw exactly what you want, go to a good metal shop specializing in stainless steel and having them custom made. Use 316 and get them electro-polished for the best corrosion resistance. Anyone I know who has either built or restored a boat and needs chainplates, unless they are simple bar stock, gets them custom made as I have in the past.
 
#15 ·
I know Harken doesn't make them. just saying a reputable brand like Harken. Your right about every rig being different. I was already thinking 316 SS, Is Electro better than hand for corrosion resistance? What about a reputable shop that i could send specs and and orignals?
 
#12 ·
MARC makes a good point as well. On boats I have seen with that type of chainplate (Peterson 34 being one) the attachment point on the hull is either a beam that ties into the keel structure or a fairly large stainless weldment that is incorporated into the hull during layup. Quite often spanning a distance of several feet fore and aft to spread the load. It does have to withstand a few thousand pounds of force. A secondary bond, even if using epoxy and expertly done, would not have the strength of original construction of this type of attachment. And that is why most builders and designers favor the attachment to either the main bulkhead or a secondary bulkhead wherever possible. The cap shroud when heeled in a good breeze exerts a lot of force on any chainplate attachment. If you wish a change best to consult a naval architect to make sure it will work.
 
#17 ·
Yes electropolishing is better as it passivates the stainless and prevents corrosion. Every major area has a shop that works in stainless. I know a good one locally I have used for 20 years but there should be one close to you wherever you are.

I do not know of a current boat with the chainplates bolted to the cabintop. The Bayliner Bucaneers were done that way though in the 70s.
 
#18 ·
If the original chain plates only attached to the deck, then the bulkhead may not be structural, but the boat can't be all that big, and is poorly designed IMHO. If the chain plates had been attached to the bulkhead by the manufacturer, they would have to be structural. It is a pretty stupid idea to attach chainplates to the "lid" of a box rather than the bottom of the box. If there's a problem with the hull-deck join, the chainplates fail by default.

I'd note that you never said the chainplates had been modified and that the attachment to the bulkhead was done by the previous owner. Having chainplates attached to a bulkhead is a pretty standard thing and it is very unusual to have them only attached to the cabintop. Must be a pretty small POS boat to have them that way.
 
#19 ·
If the original chain plates only attached to the deck, then the bulkhead may not be structural, but the boat can't be all that big, and is poorly designed IMHO. If the chain plates had been attached to the bulkhead by the manufacturer, they would have to be structural. It is a pretty stupid idea to attach chainplates to the "lid" of a box rather than the bottom of the box. If there's a problem with the hull-deck join, the chainplates fail by default.

I'd note that you never said the chainplates had been modified and that the attachment to the bulkhead was done by the previous owner. Having chainplates attached to a bulkhead is a pretty standard thing and it is very unusual to have them only attached to the cabintop. Must be a pretty small POS boat to have them that way.
I confirmed with the group that the bulkheads were never glassed in only screwed in like I said. But the headboard attached to the horizontal compression post and the original chainplates attached to part of the headboard/compression post and part of the bulkhead. Its a Coronado 25 KIT boat that was built for racing from the start nothing special by most peoples standards. allot of modifications were put into it its been down the west coast and back a few times. I think it went to Hawaii which is where i wanna take it.
 
#20 ·
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.
 
#21 ·
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
 
#22 ·
George Benson? I thought he was a jazz musician.:D

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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#23 ·
George Benson? I thought he was a jazz musician.:D

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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#24 ·
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.
 
#25 ·
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.
 
#26 ·
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.
 
#27 ·
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.
 
#28 ·
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?
 
#30 ·
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.
 
#34 ·
Not for wetting out the biax. It should never be wetted out with thickened epoxy. Here's a link to West's Fiberglass Repair Manual. You can download this and it is full of good advice for using their products or really any other companies epoxy products. Fiberglass Boat Repair and Restoration
The link to the manual is at the top of the page and the articles below are worth reading as well.
 
#36 ·
Buy biaxial tape long enough to do the tabbing you need in as many layers you wish. You won't need a lot of resin so I'd start with the 32 oz size and the matching 7oz of 206 hardener. If you need more you can get another. I think the next size up is a gallon and you shouldn't need that much unless you are going to be using it for other things. The 404 comes in a container about 4" in diameter and 11" high. That should do the job. Disposable brushes as it's not worth trying to clean them and a 3" basic roller with a few extra sleeves. Latex gloves and acetone to clean up.
 
#38 ·
For a structural bulkhead of any kind I would use 2 at least, maybe 3. Fillet the corner first with thickened epoxy by using a piece of plastic or wood that has a round corner. This stops the biax from having to take a corner and leaves it in a gentle curve. You might find it easier to cut the biax into easy to manage strips about 2' long or so and wetting them out before putting them on. Do this on a piece of plywood covered with thick plastic wrapped over the edges and stapled or taped underneath. Wet the biax thoroughly but make sure there is no excess resin as it adds nothing. Use the roller to squeeze out any bubbles. Overlap the biax, first to one side and then the other and finish up with a layer down the middle. Or use several widths of biax, starting with the narrowest and then the thicker ones.

ps You have used the quote button more in this post than I have in over 2000 posts.:D
 
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