Islander 34 chain plates

[neilsailingrn]

Hello,

Does anyone have info and pictures of Islander 34' chain plates? Mine is a 1968 model. Not the newer model.

Thanks,

Neil

[roverhi]

Don't you have them on the boat already??? If you are looking for a pattern to make new ones, pull off 2 or 3 in different locations to get any possible variation in design and check the others to be sure they fit one of your examples and then machine new ones.


The mast will stay up as long you have all the lowers supporting it or all the uppers or some combination that can include halyards while you pull the chainplates. Just BTDT replacing my chainplates. Ordered 316 stainless sheared to the proper length and a machinist friend drilled the holes and shaped the ends.

[neilsailingrn]

Roverhi, They are in place but they look suspect. I am just getting to the point of looking these over. The side stay is a nice big multi bolted stainless plate that attaches to the main bulkhead. Nice. The other 4 look like the side stay ones till they go below decks and then they are welded to a flat plate about 8" long by 4" wide 3/8" stainless. Seems they would pull the deck up in a bad prolonged blow some where in the middle of the Pacific.

[roverhi]

The problem with chain plates is crevice corrrosion where they pass through the deck. You can't tell if there is a problem without pulling them or the mast falls down.

If I get this right, your cap shrouds are bolted to the main bulkhead and the lowers are supported by a weldment to spread the load to the deck. That's not a design I'm enamored of. Unless they are very close to the hull, there will be a lot of movement of the deck so tuning the shrouds is a constantly moving game. The designer undoubtedly did his homework and designed the plate to spread the load so it won't pull through the deck as long as the deck laminate was done properly. If it makes you nervous, a fix would be laminating knees onto the hull with epoxy so you can use flat bar chain plates like the uppers. YOu could also use a rod welded bolted to the chain plate to take the load somewhere lower down on the hull. Look at a Mk 1 Catalina 36 to see how that can be done.

Anyhow, since Islander is long out of business, you'll have to pull yours to see if they are still in good condition and, if not, use them as patterns.

[neilsailingrn]

Originally Posted by roverhi

The problem with chain plates is crevice corrrosion where they pass through the deck. You can't tell if there is a problem without pulling them or the mast falls down.

If I get this right, your cap shrouds are bolted to the main bulkhead and the lowers are supported by a weldment to spread the load to the deck. That's not a design I'm enamored of. Unless they are very close to the hull, there will be a lot of movement of the deck so tuning the shrouds is a constantly moving game. The designer undoubtedly did his homework and designed the plate to spread the load so it won't pull through the deck as long as the deck laminate was done properly. If it makes you nervous, a fix would be laminating knees onto the hull with epoxy so you can use flat bar chain plates like the uppers. YOu could also use a rod welded bolted to the chain plate to take the load somewhere lower down on the hull. Look at a Mk 1 Catalina 36 to see how that can be done.

Anyhow, since Islander is long out of business, you'll have to pull yours to see if they are still in good condition and, if not, use them as patterns.

Very nice setup on that Catalina. Might go with some sort of configuration along these lines. The anchor point is the mystery but doable.

Thanks,

Neil

[cowelld]

I repaired the chainplates on a '73 Islander 30 and found three things. One, the holes in the plates are square to receive the ends of the stainless carriage bolts. Two, the holes in the main bulkhead had elongated thus allowing the bolts to tip and causing the deck caulking to open. Three, the bulkhead tabbing was breaking loose causing the main cabin door to bind.
Inspection of the main chain plates showed no physical deterioration so I elected to re-use them. The starboard bulkhead was intact and only the port side needed re-tabbing so all stress on the cap-stay was taken off and the bulkhead jacked back into compression with the hull, then re-tabbed with epoxy resin. The original was a single layer of cloth but I chose to increase the filet diameter with multiple layers. The bulkhead was seated in an fairing epoxy mix although some people want to allow that joint to be flexible. The space has to be filled no mater what to prevent rot.
The bulkhead plate hole problem was the real test. Since the chainplates have square holes it was impossible to drill them out and use hex bolts without using a huge bolt. Plus it would take a machine shop to do it. I chose to re-enforce the bulkhead holes with a "bushing" made of stainless washers and fairing epoxy mix. The bulkhead holes were drilled out to exactly the size of the washers and with the plates in place and bolts inserted the washers were buttered with the epoxy and put into the holes creating a Dagwood. You'll have to put a plastic or paper sleeve around the bolt if you don't want it epoxied in place. When the final bushing washer was inserted the fender washer end was put over the mixture and compressed. The extruded epoxy fills all the voids between the wood and the washers and creates a bonded bushing. I tested this before doing it and found it a solid solution which was echoed by Good Old Boat in an article I wrote on the process.
I had the mast un-stepped last summer and re-built the top of the compression post. That is also something to inspect in that part of the boat as long as you're suspect of the rigging. The step plate deteriorates from mast condensate unless it's been drilled for a drain hole. The plate is lag bolted into the top of the compression post and so water can also create the rot problem there.
When re-stepping the mast the yard set the aft shrouds to a minimum tension and the forwards to somewhat less than the caps. This minimizes the stress on the deck on the aft stays (the forward chainplates are set up the same as the caps). Of course they didn't tune the system to ensure the mast was in column but their explanation was that the aft stays don't take any load except in downwind sailing when it's minimum.
Hope this helps.

Good luck,
Dave

[roverhi]

If I read your post right, you filled the area between the bulkhead and hull with a non compressible fairing compound. That's not reccomended. The load of the bulkhead should be taken by the tabbing so it is spread over a larger area of the hull. With the bulkhead directly against the hull, you create a hard point that stresses the hull and can cause the bulkhead to 'print' through and show on the outside of the hull. There should be no rot problems with a gap between the hull and bulkhead. It may be even more rot resistant if the bulkhead is standing off the hull by a short distance. Any water entering can run down the hull and not soak the end grain of the plywood.

Some people make up compressable foam strips to fill the gap between the hull and bulkhead before glassing the bulkhead to the hull. I've found that putting temporary spacers in a few places to keep the space between the bulkhead and hull work just fine. Glass one side of the bulkhead with multiple layers of cloth and epoxy, remove the spacers and do the other side. Factory tabbing is usually just that, minimal glass to hold the bulkhead in place till the furniture is attached. Two or three layers of glass the full length of a bulkhead makes for a really strong reinforcement

[Cheechako]

...or you could look at it that the area filled is just distributing the load over a larger area yet along with the tabbing.....?

[neilsailingrn]

Roverhi ….I have used weather stripping in other boats for the gap between the bulkhead and the hull. Keeps the gap even. Like you said….tab one side then remove the gapping material, then tab the other side. And I use at least 3 layers of mat 6 oz. Very strong indeed. an comforting to know it is stronger than the original. Cheers, Neil

[HogGravynChtlns]

Neil, how is this chainplate project coming? I have a long list of things that need attention, While some items are more pressing I am certain that the chainplates are original and dread the thought of ripping out teak cabinetry to get in there, thanks.
Sean

[neilsailingrn]

Originally Posted by HogGravynChtlns

Neil, how is this chainplate project coming? I have a long list of things that need attention, While some items are more pressing I am certain that the chainplates are original and dread the thought of ripping out teak cabinetry to get in there, thanks.
Sean

HogGravynChtlns….I haven't gotten that far yet. I was ejected 2 weeks prior to my storage date by the good folks at Sunset Marina in South Portland Maine. "We need your space for parking" was their excuse. Seems some of the boats that have been there for at least 2 years are still there. Not nice people to deal with. So after spending about $1000 to get her to another marina and sit on a mooring for 2 weeks ($300) I finally get to put the boat on dry land again and finish my Prelauch stuff….new through hulls, cutlass bearing, 3 blade prop. All stuff that could have been done at the original location. I write this in the hopes of others spreading the word and not being subjected to this sort of treatment by these people.

Chain plates…. The main ones I'll take out and reinforce the bulkhead they are attached to and reinstall in their original locations. The forward and aft of the main one are going have a rod attached to them and secured lower in the boat. Much like the Catalina 36 setup. It's easier than trying to attach some structural member to the hull. And inspection should be easier also. So keep checking in and I'll try to keep you abreast of the latest.
Thanks, Neil

[HogGravynChtlns]

Well that was a nasty stunt they pulled on you, it's hard enough getting work done without that kind of crap, Hopefully things will go smoothly in the new location. I will anxiously follow your progress. I am assuming much of your interior in that area is disassembled? I know I would have to remove my holding tank, some plumbing, cabinetry, and too much other stuff to list just to access that bulkhead. Hopefully you can get some pictures? Thanks. Sean

[spason]

Howdy everyone. So, first I would like to publicly thank neilsailingrn, the previous owner of this boat for being AWESOME. He decided to sell this Islander 34', and my girlfriend and I are the proud new owners. We can't thank him enough!

That being said, I would love this thread to continue, as the chainplates still need to be replaced, as does the main bulkhead- it is totally rotten. I am an able carpenter, and familiar with fiberglass, but don't know nearly as much as Neil and all of you about how this should be done properly. Neil already had the plates fabricated, and they are on the boat, which is making it's way (without us- stupid work!) up the Maine coast.

My understanding is that I will cut the tabbed fiberglass that holds the rotten bulkhead completely out, make a new bulkhead, and then tab it back in. Does this just mean strips of fiberglass forming an L from the hull to the new bulkhead? Any and all advice is welcome!!

Thanks,
spason

[spason]

I almost forgot- we all love pictures don't we?

Here are both sides of the bulkhead, the chainplate in the main cabin and then the other side of the bolts in the head- 3rd pictures is the floor area at the end of the bulkhead- all quite wet and in need of replacement. My first time trying to attach pictures, bear with me- is there an easier way?

[roverhi]

The new bulkhead should stand off the hull by about a haf inch or so. You don't want the bulkhead to be a hard point. Tabbing is a bit of a misnomer. For max strength, lay up several layers of Biax cloth/Matt & epoxy resin extending six inches or more on the hull and bulkhead all the way along both sides. Polyester resin doesn't bond very well to old laminate which is why I only use epoxy.


That chainplate looks very stout.