Bulkheads & Chainplates

The Islander is a great boat, but over 25 years some potential weak points begin to show themselves. This section has descriptions of problems and solutions.

2/7/2008 - Brigid

In response to an inquiry from Sydney, Australia, Corky Stewart sent this along:

First off, I hope that it works out that can finalize your deal on Ira-Ricarda because the I-36 sails wonderfully. A properly outfitted and maintained I-36 can handle some pretty demanding conditions, keeping her crew comfortable and safe in the process.

Our boat, Brigid, is a 1978 I-36 and we, too, chose to beef up the chain plates for both the upper and lower shrouds on both port and starboard sides. I don't want to over-extend my welcome by jumping right in to give you a full narrative on how our boat mechanic re-engineered the chain plates for the upper shrouds, unless that is the level of detail you are seeking. However, attached are the pictures for how we bolstered the aft lower chain plates with a cable/turnbuckle/pad eye contraption that ties the shroud all the way to the hull. Important feature to note is the ~18-24 inch section of teak laminate that is glassed to the hull. This spreads the load across a wider area and keeps the hull from "oil-canning," as well as eliminating any single point stresses.

Anyway, we sail SF Bay in regular 20+ knot winds and we have strengthened the rig to withstand the rigors. If you would like more detail, I will be glad to provide more. Also, if it would be helpful, I will go down to the boat and take more pictures of the main chain plate hardware and how is is glassed to the hull. In my opinion, you can't "over-build" the strength of your rig, so I would be glad to provide additional information if you want it.

Should you ever find yourself in San Francisco, please look us up and we'll be glad to take you for a sail on SF Bay.

Corky & Anna Stewart, (Removed)

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Port lower extension
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Hull connection
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Starboard lower extension

2007 - Andiamo

These were sent in in 2007 from Tom Embertson, who hails from Wisconsin and sails on Lake Superior.

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andiamo lowers-1
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port chainplate under head sink
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port chainplate under head sink-2
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port chainplate bonded to hull
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port chainplate # 2

At the Fall Meeting 2002, Paul Tara invited us aboard to take pictures of the repairs he made (not a yard) to his starboard main chainplate. This is as bullet-proof a job as those done by a boatyard, so, if you feel up to the task, don't hesitate to contact Paul for more details at mamckinnon@ucsc.edu.

Looking aft into upper locker showing glass and larger chainplate. Fill hose to water tank has been removed. Lower section of main chainplate. Note extra fore and aft piece glassed in to add strength and make a pocket shelf for life jackets.
New access port to reach water tank hose connection and inside glass work. Access port in stbd. setee bunk liner to glass in a new stiffener. Note amount of hollow space behind liner, and extended chainplate.
Stbd. forward lower bulkhead reinforced. Extended main chainplate on port side.
Transfer of partial load from halyard turning blocks on deck to mast with turnbuckles.

September 1999
I36 Mon Ami
Jim Joubert

When I purchased Mon Ami three years ago, the survey determined that some of the bulkhead tabbing needed repair. The port and starboard chain locker bulkhead tabbing and the starboard upper shroud chainplate bulkhead tabbing had all come loose.

Replacing the tabbing with new glass cloth and resin is the usual method of repair. However, it was winter, and I knew it could be a messy job if it wasn't warm enough for the resin to "kick".

I found an alternate repair method in Don Casey's "This Old Boat". Casey pointed out that, typically, the tabbing comes loose from the bulkhead, while the bonding to the hull is still intact. (this was the case on my boat). The repair uses the existing tabbing and reattaches it to the bulkhead with screws and adhesive. Casey didn't provide a lot of detail regarding the actual repair, but here's what I came up with.

I pre-drilled holes for #10x1/2" stainless screws in the tabbing that was loose from the bulkhead. The screws were staggered in two rows 1 inch apart and vertically by 2 inches. After drilling the holes, I vacuumed the debris from the crack between the tabbing and the bulkhead. Swabbed the crack out with a small brush dipped in acetone to clean the surfaces, allowed it to dry, and then squirted 3M#5200 adhesive into the crack. The screws were then inserted into the pre-drilled holes and screwed down.

It was really a pretty simple repair, although the 5200 ozing out of the crack can me a little messy! (have a lot of paper towels around to wipe up the 5200!) I believe this repair it is probably stronger than the original because it uses mechanical as well as adhesive bonding to attach the tabbing to the bulkhead. The adhesive qualities of 3M #5200 are well known. It is probably as strong or stronger than the original bond. I used 1/2 inch screws as I was concerned about poking through the chain locker bulkhead into the cabin. 3/4" screws could be used on the upper shroud chainplate bulkhead if desired, but the load is mostly in shear, so the 1/2" screws are probably just as good.

This repair has seen two seasons of sailing and seems to be holding up very well.

Bulkhead Tabbing on Mon Ami (click to enlarge)

I36 Mon Ami
Jim Joubert
Mail Jim

From: Mark Wyatt[SMTP:MarkBWyatt@compuserve.com] Sent: Thursday, December 18, 1997 9:24 PM To: Gary Salvo Subject: Islander 36 Repair Question

Hi Gary!

I'm a Non-Resident Member in Southern California, and need some advice on a repair problem that's come up. I've looked over the SF Bay Message Group and surfed the Web no luck. My Islander 36 has had the port forward lower shroud chainplate support delaminate where it's tabbed to the hull. This failure occurred in the last few months, probably during a 4 hour race in 25 knot winds while beam reaching on port with some pretty nasty beam seas slamming the hull in that area repeatedly. I ain't complaining, other boats lost masts that day. I figure you 'Frisco guys have run into this type of failure and might have a good fix for it.

This part is a steel knee (triangular shaped thing) in the head cabinet which transfers the load from the shroud to the inside of the hull. The glass has failed and the knee moves up and down 1/8" when somebody jumps on the deck. The shroud was set up tight at 1250lbs static, now tension, um, varies.

Two shipyards have looked at it and their fix is to grind back the glass covering the flange and rebuild up the covering glass. I question whether I'll be facing fixing it again if that's all they do.

Could you forward this around the Association and see if someone's had this failure and how they fixed it? They can E-Mail me at MarkBWyatt@compuserve.com, or give me a buzz @714-727-7099 days 714-293-2905 home.

Mucho Thanks,

Mark Wyatt

Commodore's Reply

I had this same problem when the main port shroud let go in 1996, ripping the forward lower chain plate from the hull. It was originally repaired with "fiberglass", and it did indeed start to work loose about 2 months after it was done. The job was done a second time with a different epoxy and covered about a full foot on either side and below the chain plate. It has held up fine ever since. You can call Craig Page at San Francisco Boat Works for more details - 415-626-3275.

Also, shortly after I first got the boat in 1978 in Chicago, water leakage down the main starboard chain plate led to rot and that bulkhead replacement. In the process the yard welded a small piece of stainless angle to the chain plate just below the deck and through bolted the deck to the angle. This tied the deck rigidly to the chain plate and the bulkhead, eliminating the movement which had broken the caulk seal. The angle was also added to the port main chain plate.

Finally, the aft lowers in the older boats terminate in a plate that is only held by the deck, not the hull. I have had the deck stiffened by adding 1" thick oak strips athwartships just forward and aft of the steel plate under the headliner. I think this was changed to a hull-fastened chainplate on later model boats (mine is a '73) which don't have the upper bunk on the starboard side.

Greetings from Alaska. Glad to hear Mark is on his way to solving his problems, and great information from the members. Happy Holidays from your farthest north member. Pj (Paul Johnston)

Forward Chain Locker Bulkhead:

We had another similar problem - the tabbing on the port side of the forward chainlocker bulkhead pulled away from the hull. Again, lots of sanding and heavy glass did the trick. After 25 years at sea or so, this seems like a modest series of reinforcements.

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