I wonder about whether the lamination in the transom is sufficiently strong to take the load of the backstay without reinforcement. Perhaps someone who has done this will comment. It would seem to be a simple matter to glass in a set of reinforcement panels on the inside of the transom to accommodate a split backstay, but this would increase both the cost and complexity of the modification if such reinforcement were required.
I opted for two more bolts through the knee and a new thicker single backstay chainplate. I figure that if the original lasted 37 years this one ought to last awhile. I do have a turnbuckle type backstay adjustment device, that in it's current location requires backstay adjustment wrench that I made out of PVC pipe and a few miscellaneous pieces of hardware, but it all works just fine.
Also I like the look of the nice clean transom sans external chainplates. See photo
As I recall, extra reinforcement was added to Gene's backstay mounting knee when the backstay was replaced (see photo of blue painted backstay above). I need to take a look the next time I'm aboard his boat (#312).
I apologize for being other than clear. When I referred to reinforcement of the transom in my lasty post, I was referring to reinforcement for a split backstay. The manual already refers to the need to reinforce the knee for an externally mounted single backstay if one is installed.
There are a couple of boats out there with split backstay setups. One local boat has the chainplates externally mounted on the transome and through bolted to major backing plates.
The second boat of which I'm thinking, has internally mounted chainplates that protrude in the same manner as the stock single chainplate arrangement. How this setup is fastened, etc., I have no idea as I've only seen a photo. Not sure where the boat is located. May have been a photo on our forum . .
Ebb's planned installation has externally mounted chainplates at the outer edges of the transome. The shape of the chainplates matches the curve of the hull and then sweeps up behind the end of the toe rail. Very impressive looking. Ebb plans to install very substantial backing plates, one side of which will be curved to fit the shape of the hull. At least I think that's the plan
External manganese bronze (East Coast) plates - w a y out on the edge so that the tangs come up aft of the end of the toe rail. You'll hardly know they are there.
Because the hull "falls away" from the transom there is plenty of space inside for the washers and nuts to seat well - especially if you create a pad of mishmash (epoxy, chopped strand, cabosil) and mold it in with a piece of plywood with mylar stuck to it (two sided carpet tape sticks it.) You want to have the build up parallel to the outside of the transom.
I'll reply if anyone's interested how to acheive this miracle. By the way I can get one arm and a head up in 338's OB well from outside to work on the inside of the lazarette - no grease and no mirrors. There is a West Coast patent on this process.
Ebb
Of course we want to see it! I mean, a grown man hanging out of the bottom of a boat? Who in their right mind wouldn't?
All humor aside, when you say ' build up parallel to the outside of the transom' are you implying an even thickness of laminated backing material(epoxy, chopped strand, carbosil in your case)that would be parallel to the chainplate and perpendicular to the mounting hardware? Or is there some inherently quasi-nautical, planer geometric engineering religious thing here I'm not gettin here. Are your chainplates going to be square to the transom or will they be square or with the line created by the back stay running from the mast head to the chainplate? Which brings up another question-two separate back stays running from mast head to chainplate kind of like a running back stay or one that is split into two somewhere along its length? Can they even do that? Around here we have to use a couple of pieces of bailing twine knotted together to make a back stay. Sorry to read about the tent mishap. We hope it doesn't set you back. Tony G
wait wait wait a minnit Tony....
Parallel in my speak means only that the mishmash pad is of one thickness and in the same plane as the transom. Like a piece of plywood or mahogany. The chainplate holes are drilled thru the transom and epoxy pad allowing the washers to seat flat against the pad. It's just that no wood is used. It isn't a place that can be easily inspected.
The plates are tangs that are bent inward over the toerail ends and twisted slightly more inward so that the split single backstay triangle plate is about 5 feet off the deck. Twin backstays are frowned upon on the West Coast, mainly up in Pot Townsend
On the knee in the lazarette where the single backstay chainplate goes, I think the plywood is susceptible to water damage. The top end of the plywood is open. If the chainplate cover is not well bedded, water can leak down straight into the plywood. Can also run down into the screw holes.
Not something that you would notice happening.
Mine was good. But I still sealed up the top of the plywood with epoxy. I also ground off the paint on and around the knee and added four or five overlapping layers of biaxial tape and cloth, out to about 6 inches on each side.
Very interesting article on split backstays. Guess what I'm considering is a "forked" backstay. The article indicated that the forked backstay is not held in such low esteem as the split backstay, but nothing further was said. My question therfore becomes, should we use a single backstay with an(expensive) adjuster, or fork the backstay with a (inexpensive) backstay adjuster?
Carl Alberg and a pretty good idea. He was a designer to whom we all trust our lives. The question is how long did he intend the knee and chainplate to last before replacement, reinforcement etc?
maybe the point got smoothed over with the aquavit and beer chasers they toasted our sweet little boat with? Maybe that i/2aft knee and strap backstay anchor point was an afterthought that they never thought about again. After. Just too far 1/2aft.
I would like to hear you SAILORS go a few rounds over the forked block arrangement or the single backstay wheel johnny. And I'm not even a racer. What are the pros and cons here?
(by the way, if you are interested in the split backstay idea (NOT the dual) Bill's first photo on the ebb gallery page shows the two cast manganese tangs (chain plates) that I had been trying to carpet tape to the transom to get a look at these things just received.....when Bill arrived that day with his forensic camera.)
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