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Y26 rig tuning advice

Discussion in 'Yamaha' started by hoosgow, Mar 8, 2018. Add this thread to a FAQ

  1. hoosgow

    hoosgow

    Joined Apr 12, 2017
    5 posts, 3 likes
    Yamaha 26
    US Bellingham
    I was hoping to get some feedback/advice regarding tuning the standing rigging on a Y-26 tall rig (fractional). The original Yamaha manual specifies a method for stepping the mast and then tensioning the shrouds but they do not give either the recommended tensions or the percent of breaking strain. It specifies an amount of deflection of the shroud when side loaded a certain height above the deck.
    Here's my issues: doing a bit of calculation it is fairly simple to convert their recommendations to a tension and/or strain value and their recommendations come out very low: ~5% breaking strain, much less than the 20-25% value that most rig tuning guides recommend. I'm planning on playing around with a tighter setup to see if I can improve pointing as well as high wind performance (when the leeward shrouds can go slack when set to the factory specs).
    Does anyone have experience they could share regarding the tuning this or a similar rig? Was Yamaha just being overly conservative in their manual? Is there something else I'm missing?

    Thanks.
     


  2. kampuniform

    kampuniform

    Joined Jan 20, 2017
    53 posts, 14 likes
    Yamaha 33
    Ca Vancouver
    If it’s any help, the recommendation I’ve read suggests that 1x19 cap shrouds are optimized at 15-20% of breaking load. 1mm stretch per 2m of 1x19 wire is equivalent to 5%of the breaking load, irrespective of the diameter of the wire.

    Stainless wire returns to its original length when a load is removed; however, a grp hull does not.

    This is entirely speculative, but perhaps Yamaha’s suggestion is due to permanently reduced hull performance when loading exceeds their recommendation. Viz. the Y26 was never designed to accommodate high cap shroud tension?
     


  3. DrJudyB

    DrJudyB

    Joined Jun 25, 2004
    185 posts, 116 likes
    Corsair F24 Mk1
    003 US San Francisco Bay, CA


  4. hoosgow

    hoosgow

    Joined Apr 12, 2017
    5 posts, 3 likes
    Yamaha 26
    US Bellingham
    Thanks guys.

    Kamp, I am not too worried about the hull strength as this little Yamaha seems to be built much more solidly than most similar boats its size. I am much more concern about improving performance. That said, I don't just want to tighten things up willy-nilly and risky a failure.

    Judy, the Selden document is one of several I have read that pointed towards the use of much higher tensions than Yamaha outlined.

    I ended up buying a spinlock rig-sense tension gauge so I'll be able to make some real measurements on tension vs. performance. Now I'll be able to go changes to rig tension and how they effect performance. Racing season starts this weekend, so I can start experimenting in earnest.
     


  5. Syntonos

    Syntonos

    Joined Jan 4, 2008
    137 posts, 1 likes
    Yamaha Y25 mkII
    US Long Beach, Ca.
    Hello Hoosgow,
    I have a Y25. I've attached the Y25 manual that has a good tuning section that works for me. I figure the basics are similar to the Y26. I have Dyform rigging so shroud tension # are irrelevant. I rely more on mast performance in various conditions. I use rig tension to insure consistent set up and performance port/starboard. The previous owner had the rig board stiff. I run my rigging loose (per Y25 manual) to allow fore/aft mast bend as well as masthead to fall off (slack shroud) as wind speed increases . An easy test is to push on the mast at aboutt 5ft above deck and see if it flexes easily. If it does your in the ball park. You should be able to easily induce aft mast bent with the back stay on. I also have fresh Ullmans that make sail/mast tuning much more telling as they respond to the changes being made . Hope this helps
     

    Attached Files:



  6. hoosgow

    hoosgow

    Joined Apr 12, 2017
    5 posts, 3 likes
    Yamaha 26
    US Bellingham
    Thanks Syntonos. The big difference between the Y25 and the Y26 is that the 25 is a masthead while the 26 ifs a fractional rig. Thus, on the 25, headstay tension is primarily controlled by the backstay while on the 26, its the shrouds and the sweptback spreaders which put the initial load into the headstay. The backstay only increases headstay marginally and instead bends the upper half of the mast.
     


  7. Syntonos

    Syntonos

    Joined Jan 4, 2008
    137 posts, 1 likes
    Yamaha Y25 mkII
    US Long Beach, Ca.
    Your correct on the mast head vs. fractional. I just wanted to make the point looser seems to work better than stiff on my boats performance. You may want want to look up a Thistle one design tuning guide , as well as others, that use a fractional rig. Thats where I cut my jib back in the day and applied the same tuning principles , just different tools to adjust mast bend / flex. Once I did that the boat began responding well . Have you looked in the Archives of this forum. Seem to me someone was campaigning a Y26 in San Francisco quite a while back. There may be some clues there. We Yamaha guys have limited resources...... this is the best one I've found by far.
    Cheers - have fun
     



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