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Thread: wooden mast spreader end fittings

  1. #1
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    Default wooden mast spreader end fittings

    Gentleman,
    One of my projects is creating a mast for a 1940's Arrowhead 21 sloop. The 1925 solid fir mast, from another boat, that will be planed down, has two sets of oak spreader arms. These arms have small bronze fittings that slide over the wood tips and have a slot and a set screw to lock the wire stay in place. Is this a good idea? Should the stays have the option of some movement? Or should they be locked in place? Will the bronze set screw damage the wire? Thanks for any help.

  2. #2
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    Default Re: wooden mast spreader end fittings

    They are usually locked in place vertically, but their are two basic designs, swinging (fore and aft) and fixed spreaders. Both have specific reasons. I would use the as-designed arrangement.

  3. #3
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    Default Re: wooden mast spreader end fittings

    Ideally you'll cock the spreaders such that they exactly bisect the angle they create in the stays. Then the down pressure is reduced to zip. It never hurts to seize the stay in the area where it lands.

    I like it when spreaders can move fore and aft a bit. When the stay is taught, the spreader is forced to its best place so having allowable flex there cannot hurt. Since masts pump and things on boats move - like the alignment of the stay will change if you rake or unrake the mast in tuning - having the spreader to mast attachment rigid can only induce stress that really can lead to spreader failure.

    G'luck

  4. #4
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    Default Re: wooden mast spreader end fittings

    Excellent info. Thanks

  5. #5
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    Default Re: wooden mast spreader end fittings

    I guess bronze is softer than stainless.

  6. #6
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    Default Re: wooden mast spreader end fittings

    Herrehoff advocated using a serving above and below the spreader tip to keep it on the right angle with a metal tip cover. Mine have a fine copper inner liner on the tips as well. Marlin is good to use as it soakes up the black artists acrylic paint making a water barrier on the serving.
    Jay

  7. #7
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    Default Re: wooden mast spreader end fittings


  8. #8
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    Default Re: wooden mast spreader end fittings

    Looks good. Mine are much smaller; 24' x3"x3" mast with 1/8" wire. I don't see damage from the bronze set screws on the stainless wire, so I might just make sure the end of the screw is nice and flat & not over-tighten them. Also seems like there is an advantage to having the for and aft pivot at the mast/spreader connection point.
    As usual, thanks for the help.

  9. #9
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    Default Re: wooden mast spreader end fittings

    The ability of a spreader to pivot at its heel makes it self aligning for load direction as the boat pitches and gyrates.
    It also eliminates the nasty habit of having the spreaders torque out the fastenings at the heel. Note the copper liner on the inside of the groove for the wire here. Helps prevent splitting and chafe.
    Jay

  10. #10
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    Default Re: wooden mast spreader end fittings

    Looks like your system keeps the outer end of the spreader in place but not as rigid as the set screw on mine. I'm wondering if my smaller mast with the double sets of spreaders will be stiff enough to maybe not move much nor result in damage from the set screws. ??????

  11. #11
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    Default Re: wooden mast spreader end fittings

    How about posting a picture of your set screw set up? I really can't comment on what is not a clear description.
    Jay

  12. #12
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    Default Re: wooden mast spreader end fittings

    Good advice from Ian and Jay on having some fore and aft movement on the heel of the spreader. Here's a spruce spar that collapsed with no warning.



    A friend who is a rigger showed me what he figured was the culprit. As well as not moving(by design), it looks like somebody over-did an epoxy plug. Sure the plug is strong, but not the little bit of spruce that was left around it.

    Hard to say if the heel couldn't move fore and aft or the added stress (a spinnaker in high winds I think) simply collapsed the spreader connection, under the compression.


  13. #13
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    Default Re: wooden mast spreader end fittings

    No Bueno! The epoxy acted as a wedge and destroyed the wood around it. Joining two materials of a different modulus of elasticity usually ends up doing that. This is why plywood, classically de-laminates. Sorry to see that! The person that did that work didn't have a clue!
    Jay

  14. #14
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    Default Re: wooden mast spreader end fittings

    Here are some photos of the bronze end fittings in question. They can be seen here: http://imgur.com/a/wpC9o Thanks all.

  15. #15
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    Default Re: wooden mast spreader end fittings

    Those spreader tip fittings look to be well thought out. If the machine screws are bronze, you should have no chafing problems. A bit of loc-tite 567 will prevent the screw from backing out but is easily removed when needed.
    Jay

  16. #16
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    Default Re: wooden mast spreader end fittings

    Sounds good. The mast is from a 1925 sailboat. I didn't see any wear or damage to the stays from the screws. Other than polishing the ends of the screws flat, I think I'll use them as is. The mast/spreader connection is a single, vertical bolt that allows some forward/aft movement of the spreader. Appreciate the help and opinions. Thanks

  17. #17
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    Default Re: wooden mast spreader end fittings

    If the existing screws are stainless steel, you won't see any scaring on the wire but, it will polish a reduced area on the rigging wire.
    For that reason, I would still suggest you use bronze machine screws as they are softer than the wire and won't wear on it.
    Jay

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