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Thread: Mast tuning and raise lower 25+

  1. #1
    Junior Member
    Join Date
    Jun 2019
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    Michigan
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    9

    Mast tuning and raise lower 25+

    Tuning Mast:
    I have a 25 plus with a twist near the top of the mast. I followed the tuning directions from Ericson to a tee and didn't seem to improve the twist?
    My friend suggested checking the spreader lengths and angles. Any other thoughts?

    I also noticed that the chain plate for the upper and lower stays are about even (Bow & Stern) with the base of the mast. This really surprises me as the Ericson's directions say the aft stay does not increase forestay tension and to keep the rear lowers loose. (Then what counters the forestay tension?)

    Raise & Lower Mast:
    The only thing I can think of why they have the chain plate for the upper & lower stays located even with the center of the mast base is for use of a Gin pole to raise and lower the mast with the lower side stays still attached, but loosened. Any Experience with this practice?

    Thanks
    Last edited by Stringert; 09-08-2019 at 07:22 PM.

  2. #2
    Contributing Member III
    Join Date
    Feb 2001
    Location
    Newburyport,Ma.
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    59
    can you send a couple of pictures looking up main sail track ??

  3. #3
    Principal Partner
    Join Date
    Oct 2003
    Location
    Chicago, IL
    Posts
    1,835
    The location of the chainplates has nothing to do with the use of a gin pole. The arangement was very typical of the time, and the mast has a set of upper shrouds, and forward and aft lowers. The backstay DOES increase headstay tension (you might be misreading something), but since the rig is fractional, it is not as directly effective for headstay tension as with a masthead rigged boat. The forward lowers both help keep the mast in column sideways, and can also be set to induce some mast bend (pulling the middle section of the mast forward), which can be useful in flattening the mansail, if desired, in heavier winds. The at lowers of curse restrict mast bend, and also the "pumping" movement of the mast as you hit waves. The correct setting depends on conditions, how full or flat the mainsail is from the sailmaker, and whether or not you have a backstay adjuster. If the mainsail is very full and you sail in a windy area, you will want tighter fwd lowers and looser aft lowers. If the mainsail is flat, you will want them generally equal so that mast does not bend (but never bends backward). If you still have too much headstay sag for your liking, tighten the headstay turnbuckle . Search this site for other posts on mast tuning-there is a lot. Cheers

    Quote Originally Posted by Stringert View Post
    Tuning Mast:
    I have a 25 plus with a twist near the top of the mast. I followed the tuning directions from Ericson to a tee and didn't seem to improve the twist?
    My friend suggested checking the spreader lengths and angles. Any other thoughts?

    I also noticed that the chain plate for the upper and lower stays are about even (Bow & Stern) with the base of the mast. This really surprises me as the Ericson's directions say the aft stay does not increase forestay tension and to keep the rear lowers loose. (Then what counters the forestay tension?)

    Raise & Lower Mast:
    The only thing I can think of why they have the chain plate for the upper & lower stays located even with the center of the mast base is for use of a Gin pole to raise and lower the mast with the lower side stays still attached, but loosened. Any Experience with this practice?

    Thanks

  4. #4
    Principal Partner
    Join Date
    Sep 2013
    Location
    Port Angeles, WA
    Posts
    891
    I am a little confused by the description "twisted mast" Do you mean it twists a little like a corkscrew does or do you mean it bends in a fore and aft manner? If it twists, that is bad. If it bends, that is good. The masthead rig is stronger. The fractional rig allows much more bend which pulls the fullness out of the main in windier weather. In lighter air, you ease the tension on the backstay and the mast straightens. When the wind blows harder, you tighten the backstay and the mast bends pulling the sail flatter for better performance.

    When raising or lowering the mast the lower shroud opposite the way the mast is going to swing down is removed is loosened and removed, then The forestay is loosened and removed. Be sure the gin pole is set up and the jib halyard are attached first. I have a line rigged from the block on the bow back to the primary winch that is used to attach to the gin pole to raise and lower the mas on the SJ26. That allows the primary winch to be used to raise the mast. I also use the same line as a downhaul by snapping it to the ring at the top of the sail. so I can pull it down from the cockpit and fasten it so it can't climb back up the forestay. I made the gin pole a spinnaker pole to make it long enough to be a good lever.

    I got to the point that I could rig the boat and be in the water in 35 minutes with an experienced helper and in 45 minutes by myself. So it can be done but it takes practice. My first try took 2 1/2 hours with Three experienced helpers.

    That ability to yank the boat out of the water add travel 1200 miles on the freeway to a new cruising area is invaluable not to mention winter storage beside the garage.
    Last edited by supersailor; 10-30-2019 at 02:56 PM.
    Bob Morrison
    1987 E-34 Hull #15
    "Terra Nova"

  5. #5
    Principal Partner
    Join Date
    Sep 2013
    Location
    Port Angeles, WA
    Posts
    891
    Taking a little closer look at the 25+, you have an aft lower and a center lower. There is no foreward lower, That makes mast raising and lowering easier. You do not have to loosen and detach any of the shrouds to lower the mast. The gin pole attaches at the bottom of the mast and the shrouds stabilize the mast on the way up. I have a system that makes the whole thing easier should you ever decide trailering is your thing.

    The aft shroud determines how much bend is allowed in the mast. The backstay takes the load as the shroud tighens up during the bending process. The backstay tension should be released when the boat is not being used. Your mast is probably still under tension at rest so it would be bent.

    It would really be helpful to hook up with an experienced sailor in your area that understands mast bend and how to use it.
    Last edited by supersailor; 10-30-2019 at 04:49 PM.
    Bob Morrison
    1987 E-34 Hull #15
    "Terra Nova"

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