The chainplates on my 1972 Islander 36 are weak - bolted to a bulkhead that is not bonded to the hull. I understand this is common on early models and not safe for off shore sailing. Has anyone modified their chainplates? Please tell me how you did this. Thanks.
Strengthing chain plates Islander 36
- Thread starter Bill Crysler
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On an Islander 30
1968 design the upper shroud chain plates penetrated the deck and bolted to the bulkhead, the lowers were flat plates with a lug welded to the plate and stuck up through the deck and held in place by a couple of small screws. I took them out entirely and made new chain plates that I installed outboard on the hull. For this I purchased enough 316 stainless steel bar stock. Marked the angle of the shrouds on the hull and bent the bars to conform to the shape and curve of the hull. I drilled each one for four bolts and the toggle below the turnbuckle .After that I repaired the holes in the deck left by the original plates. Since I was doing a complete refit I also reinforced the hull in the way of the new chain plates.
1968 design the upper shroud chain plates penetrated the deck and bolted to the bulkhead, the lowers were flat plates with a lug welded to the plate and stuck up through the deck and held in place by a couple of small screws. I took them out entirely and made new chain plates that I installed outboard on the hull. For this I purchased enough 316 stainless steel bar stock. Marked the angle of the shrouds on the hull and bent the bars to conform to the shape and curve of the hull. I drilled each one for four bolts and the toggle below the turnbuckle .After that I repaired the holes in the deck left by the original plates. Since I was doing a complete refit I also reinforced the hull in the way of the new chain plates.
Chainplates
Thanks Ross. Your solution sounds strong and the way I wish they were positioned in the first place. While perhaps not as strong as your solution, I was wondering about tabbing the bulkhead to the hull. What do you think of that? But you've inspired me to think of the outboard option. Thanks again. Bill
Thanks Ross. Your solution sounds strong and the way I wish they were positioned in the first place. While perhaps not as strong as your solution, I was wondering about tabbing the bulkhead to the hull. What do you think of that? But you've inspired me to think of the outboard option. Thanks again. Bill
Going Outside
I have a 1971 Ericson 29 and I want to replace all of the rigging. I don't feel this would be complete without probably replacing the chainplates which are embedded in the hull. Makes it impossible to inspect them. If I have brand new rigging but the chainplates can still be a source of concern does not do me much good. I considered doing the same thing as Ross and am glad to hear someone else did it. I had the same feeling, moving these outboard and through bolting to the hull would give me new steel strongly attached to the boat and much easier to inspect etc. My only question is what do you use to bend and shape the stainless steel? Do you make a form out of wood and bend it over this? Figure I could go to a machine shop and have them do it too.
I have a 1971 Ericson 29 and I want to replace all of the rigging. I don't feel this would be complete without probably replacing the chainplates which are embedded in the hull. Makes it impossible to inspect them. If I have brand new rigging but the chainplates can still be a source of concern does not do me much good. I considered doing the same thing as Ross and am glad to hear someone else did it. I had the same feeling, moving these outboard and through bolting to the hull would give me new steel strongly attached to the boat and much easier to inspect etc. My only question is what do you use to bend and shape the stainless steel? Do you make a form out of wood and bend it over this? Figure I could go to a machine shop and have them do it too.
In my case that wasn't
an option. The bulkhead was rotted. I discovered that the bulkhead was tabbed below the cabinets but it had let go. Mostly the failure was tabs to the wood but in some places the failure was glass to glass. I bedded my chain plates in high grade caulk instead of the usual putty type bedding compound. I never expect to remove them. There was one thing that I did that I haven't seen recommended. I have a large countersink and I used it to chamfer the bolt holes in the hull. So that when the bolts were drawn up tight some of the caulk would form a ring around the bolt shank and not all be squeezed out. If your shrouds are still good, plan to make the chain plates long enough to attach to the shrouds. AND ONLY LOOSEN ONE SHROUD AT A TIME and then back that one with a halyard.
an option. The bulkhead was rotted. I discovered that the bulkhead was tabbed below the cabinets but it had let go. Mostly the failure was tabs to the wood but in some places the failure was glass to glass. I bedded my chain plates in high grade caulk instead of the usual putty type bedding compound. I never expect to remove them. There was one thing that I did that I haven't seen recommended. I have a large countersink and I used it to chamfer the bolt holes in the hull. So that when the bolts were drawn up tight some of the caulk would form a ring around the bolt shank and not all be squeezed out. If your shrouds are still good, plan to make the chain plates long enough to attach to the shrouds. AND ONLY LOOSEN ONE SHROUD AT A TIME and then back that one with a halyard.
When I bent
The steel for the new chain plates I use a large vise, a bar clamp, a two pound hammer and a heavy block of wood ( actually a piece of fire wood that hadn't been split. When the tree cutters are working in my neighborhood I beg a piece about two feet long). I made a few marks on the blank with a felt pen to show where the curves ended. There are some offsets that were a little tricky. I just worked slowly and checkeed often. It helped that I had the boat right next to the house and all of my tools. But for bending a gentle curve in a steel bar lay it flat on the block of wood put a glove on the hand that doesn't hold the hammer and and start striking the bar along the section where you want the curve. You want many light to medium force blows not a few heavy ones. Gradually the bar will take on the curve that you want. When is starts to look like it is close lay it in place and check. Sharper bends use the vise and the clanp. The clamp lets you apply the bending effort to the bar between the vise jaws and the clamp jaws and you can in this manner bend a fairly tight radius. If you find that the curves are right but there is a twist , then clamp the work in the vise and using the bar clamp like a wrench twist the work into shape. I can say more if you need.
The steel for the new chain plates I use a large vise, a bar clamp, a two pound hammer and a heavy block of wood ( actually a piece of fire wood that hadn't been split. When the tree cutters are working in my neighborhood I beg a piece about two feet long). I made a few marks on the blank with a felt pen to show where the curves ended. There are some offsets that were a little tricky. I just worked slowly and checkeed often. It helped that I had the boat right next to the house and all of my tools. But for bending a gentle curve in a steel bar lay it flat on the block of wood put a glove on the hand that doesn't hold the hammer and and start striking the bar along the section where you want the curve. You want many light to medium force blows not a few heavy ones. Gradually the bar will take on the curve that you want. When is starts to look like it is close lay it in place and check. Sharper bends use the vise and the clanp. The clamp lets you apply the bending effort to the bar between the vise jaws and the clamp jaws and you can in this manner bend a fairly tight radius. If you find that the curves are right but there is a twist , then clamp the work in the vise and using the bar clamp like a wrench twist the work into shape. I can say more if you need.
Chainplate Replacement (Islander 40)
Regarding Chainplates: If the bulkheads are rotting, you must replace them lest you want to experience a lack of torsional rigidity. You can scarf a new piece in or replace the whole damn thing. If not rotting, but not taped to the hull stringer, tape it using foam and 3 layers of epoxy wetted glass 17 oz Knytex or similar is what I used. If you are still uncertain, attach new chainplates to the stringer (fabricate longer plates). Chainplates on my boat were a combination of Aluminum and Stainless which led to corrosion, I replaced them after a dismasting with all 316 stainless at a cost of $450 US in 1998. Today I would fabricate Carbon chainplates going overboard on the stength specifications so that I would not have to do it again. If there are any rust stains on your chainplates you should vigorously clean it to find the crack that is waiting to cause your next dismasting. Good luck.
Regarding Chainplates: If the bulkheads are rotting, you must replace them lest you want to experience a lack of torsional rigidity. You can scarf a new piece in or replace the whole damn thing. If not rotting, but not taped to the hull stringer, tape it using foam and 3 layers of epoxy wetted glass 17 oz Knytex or similar is what I used. If you are still uncertain, attach new chainplates to the stringer (fabricate longer plates). Chainplates on my boat were a combination of Aluminum and Stainless which led to corrosion, I replaced them after a dismasting with all 316 stainless at a cost of $450 US in 1998. Today I would fabricate Carbon chainplates going overboard on the stength specifications so that I would not have to do it again. If there are any rust stains on your chainplates you should vigorously clean it to find the crack that is waiting to cause your next dismasting. Good luck.
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