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Thread: Backstay Chainplate Discussions [pg 152 in Manual]

  1. #1
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    Backstay Chainplate Discussions [pg 152 in Manual]

    I'm having a few parts made, including an new backstay chainplate, and on page 152 of the manual I can't read the bend angle. It didn't copy too well. Someone with a better copy able to read it? Thanks!
    Kent

  2. #2
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    We must have the antiquated first edition here for there is no page 152 in this beat-up and tattered manual. There is, however, a spec sheet that has an angle of 57 degrees and 113's back stay chain plate was fashioned to that angle and seems to have worked for the previous owner and will suit my needs I suspect. Tony G.

  3. #3
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    57degrees sounds right

    Thanks.

    I looked really hard and it appears the second number is a seven! Thanks for the first number.
    Kent

  4. #4
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    If you're replacing the backstay chainplate, I'd recommend using thicker stock than Pearson used. They seem to bend a bit. Here are a couple of examples:
    Attached Images  
    Last edited by Bill; 01-16-2003 at 07:49 PM.

  5. #5
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    Or, this one:
    Attached Images  
    Last edited by Bill; 01-16-2003 at 07:56 PM.

  6. #6
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    The 2nd chainplate came out of #76. I had no idea it was anything other than perfectly straight, until I tried to remove it. Could not understand why it would not pull straight down . .

    The first chainplate came from #312. It got that shape because of a collision with a piling! The sudden stop pulled the backstay chainplate half way through the lazeratte hatch!

    Additional anchoring bolts near the top of the chainplate would appear to be in order. Or, do as Ebb is planning and go to a split backstay.
    Last edited by Bill; 01-16-2003 at 07:57 PM.

  7. #7
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    Good night!! 113 had a couple of boxes of 'junk' that the previous owner threw in with the deal and the original chain plates were among the parts and pieces. They looked pretty thin but that scares me! 'Sure am glad he replaced them with 1/4" and moved the backstay over the stern. I can deal with a little stainless showing better than mangled boat parts. Now I'm gonna have to look at the chain plates on my other boats just outta paranoia.

  8. #8
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    Super Size it--- OK

    Bill,

    Your photos have convinced me to go with a thicker piece of stainless. As they say, a picture is worth a thousand words. Very convincing!!
    Kent

  9. #9
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    IMPORTANT DISCOVERY

    Today, as we were measuring for a replacement backstay chainplate, my machinest friend and I discovered that the "bent" original may have come that way from the factory

    It seems that the knee to which the chainplate is attached, is located dead center of the boat. To get the chainplate centered so the backstay would be centered, it appears Pearson gave it the double bend shown in the above photo of the chainplate from #76. We varified this by peeking through the chainplate slot in the deck.

    Given the way these boats were put together, your results may differ :

  10. #10
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    OK, I give up. I thought I knew what I was doing. My brand new 304 stainless steel extra-thick backstay chainplate backstay chainplate fits flat against the knee, and slides ever so nicely up through the slot in the deck. It was made by the same shop that made an identical chainplate, using the original very thin and very tired original backstay chainplate on hull #330 as a model. I did not use the earlier version made by that shop since my contractor subsequently drilled some extra holes in it that in my opinion made it less than sound.

    The contractor removed and disposed of my old chainplate, so I never saw it out of the boat. I do know that before it was removed, the original factory-installed chainplate showed sings of metal fatigue at the very top from twisting by the backstay tension adjuster, but I do not recall a bend.

    I have been sailing around in the ocean all fall happily with my new staright-as-an-arrow backstay chainplate installed, and it seems to work just fine. I did add a couple of extra bolts through the knee above the three factory-drilled bolt holes. I cannot conceive of why one would need to bend the backstay chainplate, since the backstay chainplate slides right up through the deck slot, and bolts securely to and flat against the knee, and since the backstay wire rises ever so nicely from the top of the chainplate at the center of the transom to the mast head.

    My last boat, a Catalina 22 had a single backstay that was tied to a chainplate set deliberately off center to keep it out of the way of the transom-mounted traveler. Bending the backstay chainplate seems less structurally sound than an ever-so-slightly off center backstay attachment point.

    So my question is: Why bend the thing at all?
    Scott

  11. #11
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    Scott, good question Our analysis may be faulty and it may be just happenstance that the bend in ours takes the cp through an out-of-line hole above the knee. Your extra thick, 304 ss chainplate sounds good to me. I think I better take another look through that hole in the deck . . .

  12. #12
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    Holding OUT!

    Bill,

    If you would make your eagle eye inspection and post what you think is going on I'd appreciate it! I haven't had anything fabricated yet--- this is one of those things that has three chapters to it, and by my count, we're probably at chapter two, one more to go to get sanity!
    Kent

  13. #13
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    SIGHTING FOR . . .

    Ok, took another sighting down the chainplate hole today and saw the knee filling in the view, but not all of it

    Next, used a straight edge poked down the hole, and yes, it did fit . . .

    So, I guess you should ignore my original post, although I still think Pearson bent my chainplate a little to fit . . .

    Ebb has the right idea, go to a split backstay . . .

  14. #14
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    Too much ching?

    Bill
    I've been watching the backstay chainplate story unfold. I believe you when you say Pearson bent your chainplate. I'm young but I've seen weirder things done on the job and maybe that's why I choose to be self employed and away from that sort of time clock mentality. But I am interested in why you think that a split backstay is the way to go. Is it more performance that you're seeking by tuning the mast? Or maybe it's the additional security of spreading the stress over a larger area? If it's tuning why not go to a hydrolic adjuster? Tell me anything other than it's just deep pockets of west coast money
    Tony G

  15. #15
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    Yikes, talk about cost. An hydraulic adjuster runs about $1,000 so it's not a consideration. A wheel adjuster runs about $325 and a turnbuckle adjuster about $185 for our wire size. A split backstay adjuster, however, is only $30

    My reason for going to a split backstay is primarily race related - makes adjusting the backstay easy and is cost effective (see above). The shrouds are due for replacement (1988) so the marginal cost of splitting the backstay cable will be low relative to the total. The "only" added expense is getting the chainplates fabricated and installed.

    A secondary consideration is what appears to me to be the under engineered backstay attachement (that little knee in the lazarette). It's lasted only 40 years, but still . . .

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