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Thread: standing lug sail yard twist

  1. #1

    Default standing lug sail yard twist

    Howdy forum.

    I am very new to posting on the forum. I have lurked for a few years and gathered a lot of great information. Thanks to many!!!

    I sail a Penobscot 14 with a standing lug/ jib set up.

    here is a link to my build blog: http://penobscot14-sailboat.blogspot.com/

    My mainsheet runs from a cam cleat on the centerboard trunk up to a block on the boom, along the boom aft to a block near the end of the boom, then down to a yoke traveler that is mounted to transom quarter knees.

    For my 67 sq. ft. standing lug, this system works great.

    I have been doing quite of bit internet and forum searching to try and learn more about sail trim and specifically sail twist control using this kind of mainsheet system.

    I have found some info, but not a lot. So far, I have set the yoke at a given length and left it that way. I could shorten the yoke if need be, but not lengthen it much because it will get to close to the end of the boom. To make adjustments to the yoke length, I would need to add a cleat somewhere.

    What adjustments would I make, when would I make them, and what would the effects on the sail twist be with a given adjustment.

    I am having a difficult time understanding how changing the length of yoke affects the leech tension thusly affecting sail twist.

    Part of the reason that I am trying to figure this out is because I have wondered about eliminating the yoke. But after reading forum post on this, I think that the end of boom sheeting is beneficial for sheet and boom loads.

    Thanx,
    Fair Winds,
    Vince

  2. #2
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    Default Re: standing lug sail yard twist

    Here's a few ideas to work through.

    The yard pivots about the halyard attachment point, so you can pull down on the aft fixed main sheet to tighten the leach or you can pull down on the luff, which pulls the end of the yard upwards and hence tightens the leach.

    When you pull down on the leach with the main sheet you are pulling up on the luff and if there is insufficient downhaul in place you will actually raise the front of the yard and get nowhere. You will also be creating a sail which does not open naturally in gusts. You are looking for a stable shape but which is also reactive to gusts.

    So, in our racing lug rigs, we concentrate on a lot of downhaul applied to the luff. We find this is essential in racing performance and makes a huge difference to pointing ability and general speed. Typical downhaul ratio will be 6:1, some even more.

    You will be be please to hear that our local lug rig racing classes all use full transom width horses for the main sheet blocks.

    Hope this helps

    Brian

  3. #3
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    Default Re: standing lug sail yard twist

    First off, you did a beautiful job with this boat. Every detail is stellar. Congrats.

    And here's a shot borrowed from your website. My preference would be to shorten the traveler so that the sheet is free to slide across and follow the boom. If it's high as shown, the thimble is going to get hung up on center and induce more twist than you probably want. If it doesn't slide freely, a larger thimble may be called for, but I doubt this would be necessary.

    -Dave

  4. #4
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    Default Re: standing lug sail yard twist

    This website is a wealth of information regarding Lug sails, it's authored by Michael Storer (Of Goat Island Skiff fame), who has been working on advocating lug-sails for simple and racing craft for a while.

    http://www.storerboatplans.com/GIS/GISRigging.html

  5. #5
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    Default Re: standing lug sail yard twist

    I got distracted in the midst of posting, and asrainox beat me to it. The storer site is worth the read, although the focus is on balanced lugs and I'm not sure how much crosses over to standing lugs.

    You made a stunning boat. I don't allow myself to have things that nice because I'm not considerate enough to give them the quality of respect and care they deserve.
    Last edited by cracked lid; 01-11-2014 at 06:32 PM.

  6. #6
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    Default Re: standing lug sail yard twist

    Lovely boat -
    I have rigged a vang with success on a standing lug rig.

    (A detail about reefing a loose footed sail...
    I don't tie the reefpoints around the boom, but just bundle up the sail.)


  7. #7
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    Default Re: standing lug sail yard twist

    If you had a substantial and effective vang, you could get that sheet and traveller completely out of the way behind you and just sheet with a dinghy style purchase to the aft end of the CB trunk. That's the most handy and least obtrusive way to do it by far.

  8. #8
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    Default Re: standing lug sail yard twist

    I have practically the same set us as you on my Michalak family skiff, though the sheet does not come down to anything except my hand. I do however have a becket block on the rope sheet horse,which gives a small advantage as this tends to flatten the leech when pulled up tight . I may be able to find a picture.

  9. #9
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    Default Re: standing lug sail yard twist

    Howdy, the Goat Island Skiff sailors and OzRacer sailors always shared a lot of information about boat setup and so on.

    However when Brian (Keyhavenpotterer above) rolled up on the forum he kicked us off into a bunch of different directions.

    There are quite a few useful articles on boat setup. Here

    And Follow the links after the short into article Here

    Hope that helps too
    Michael

  10. #10
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    Default Re: standing lug sail yard twist

    I've tried rigging a bendy boom with central boom sheeting and multiple parts to my swivel cam on the centerboard trunk, but I found that it didn't bring in the boom enough for proper upwind sailing. I went to a rope yoke, but now I have another system.:You could replace the yoke with blocks at each quarter, then lead your mainsheet down from the block at the end of the boom to one quarter, across the transom to the other quarter, then up to dead end at the end of the boom.

  11. #11
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    Default Re: standing lug sail yard twist

    This works for me, puts the power where you need it, and slides across when you want it to.
    It really is quite difficult to build an ugly wooden boat.

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  12. #12
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    Default Re: standing lug sail yard twist

    Hi folks...Glad I found this thread though here we are in 2020. Great information on here relevant to my current situation so I’m hoping all you smart builders are still around. (I’ve frequently referred to the well-documented EZ Duzzit blog during my own P.14 build.) “Connie” is just about ready to get her feet wet, though at this self-isolating time she may have to get mounted on the wall instead. I’m just finishing up construction of the spars for my standing lug rig and decisions need to be made. Yesterday I made a really nice little mast collar as shown in the plans for the boom jaws to nudge up against. I didn’t attach it yet and after reading this thread it seems like it may be unnecessary if I rig a down-haul as I intended. True? Another question is whether the masthead halyard sheave run fore/aft or athwartships. Arch Davis suggests a dipping line attached to the heel of the yard and I like that idea. (I have history in the home of Beer Luggers from Devon, U.K. Where the “dipping” lug is traditional, albeit an entirely different kettle of fish so to speak, as the tack is hauled around the mast and re-attached forward.) If I rig the dipping line the halyard will need to fun fore/aft. Any thoughts? Does dipping work well on this small rig?
    Sorry for this long-winded post, but I have time on my hands during the quarantine.
    Thanks all.

  13. #13
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    Default Re: standing lug sail yard twist

    I'll say don't install the collar until you try it without, and try different tensioning / downhaul on the standing lug.
    I'd run the halyard athwartships, but if you have a square mast step you should be able to rotate the mast 45 degrees if desired.
    Got nothing on dipping rigs.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  14. #14
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    Default Re: standing lug sail yard twist

    Quote Originally Posted by johndowney View Post
    Hi folks...Glad I found this thread though here we are in 2020. Great information on here relevant to my current situation so I’m hoping all you smart builders are still around. (I’ve frequently referred to the well-documented EZ Duzzit blog during my own P.14 build.) “Connie” is just about ready to get her feet wet, though at this self-isolating time she may have to get mounted on the wall instead. I’m just finishing up construction of the spars for my standing lug rig and decisions need to be made. Yesterday I made a really nice little mast collar as shown in the plans for the boom jaws to nudge up against. I didn’t attach it yet and after reading this thread it seems like it may be unnecessary if I rig a down-haul as I intended. True?
    You need both. Take the tack downhaul through the boom, to keep it down, but fit the collar to support it when reefing.
    Another question is whether the masthead halyard sheave runs fore/aft or athwartships.
    Iether, it does not really matter
    Arch Davis suggests a dipping line attached to the heel of the yard and I like that idea. (I have history in the home of Beer Luggers from Devon, U.K. Where the “dipping” lug is traditional, albeit an entirely different kettle of fish so to speak, as the tack is hauled around the mast and re-attached forward.) If I rig the dipping line the halyard will need to fun fore/aft. Any thoughts? Does dipping work well on this small rig?
    No, the whole point of a STANDING lug is that you do not dip it. Unless you create slack somewhere in the sail, and with a boomed sail the only way to do that is with the halyard the yard will not dip.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: standing lug sail yard twist

    I found that my own standing lug sailed closer to the wind on the "bad tack" This was hard to accept at first but continued experiments over a year or so on the same one mile course irrevocably proved it. We have a pretty steady "trade wind" here.
    The sail in spite of the added windage of the mast, set flatter.

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    Default Re: standing lug sail yard twist

    Quote Originally Posted by Canoeyawl View Post
    I found that my own standing lug sailed closer to the wind on the "bad tack" This was hard to accept at first but continued experiments over a year or so on the same one mile course irrevocably proved it. We have a pretty steady "trade wind" here.
    The sail in spite of the added windage of the mast, set flatter.
    All the sail experts I respect say pretty much the same thing.
    David G
    Harbor Woodworks
    https://www.facebook.com/HarborWoodworks/

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

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    Default Re: standing lug sail yard twist

    I found that my halyard ran more smoothly when I set the mast athwartships. I agree about a big down purchase downhaul. I leave it slack, take the yard up and then haul down on both my standing luggers. Neither has a boom so these are easy to rig. Both have full battens and have very high aspect ratios. On RANTAN the oar and sail boat I had the sail cut to provide some vanging.
    Ben Fuller
    Ran Tan, Liten Kuhling, Tipsy, Tippy, Josef W., Merry Mouth, Imp, Macavity, Look Far, Flash and a quiver of other 'yaks.
    "Bound fast is boatless man."

  18. #18
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    Default Re: standing lug sail yard twist

    I also have my halyard block athwartship and found it works better for me. Along with the double downhaul made very tight. For me I am liking not having a traveler, my sheet runs up to the end of the boom from a fixed central point, I like that I can center the boom more easily. This works since I have a push-pull-tiller.

    I have a question and am looking for input on how I am currently running my halyard. I don’t remember where exactly now, but I started noticing in a old illustrations of small lug sails the halyard running from the top of the mast to the bow then back to the mast base or cockpit. Becoming a forestay. I have started doing this and am liking it. The halyard/forestay gives me a nice strong force to set the sail to when I am beating. It is working great, I am out pointing many boats and the sail is setting quite well. One tricky part of it is when raising the sail I have to be careful to to over tension the halyard. As soon as the sail is up, the angled halyard/forestay starts to pull the mast too far forward. But set just right it is good.

    what is your opinion of this type of halyard running?
    "Yeah, well, that's just, like your opinion man"
    -The Dude-

  19. #19
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    Default Re: standing lug sail yard twist

    I also have my halyard block athwartship and found it works better for me. Along with the double downhaul made very tight. For me I am liking not having a traveler, my sheet runs up to the end of the boom from a fixed central point, I like that I can center the boom more easily. This works since I have a push-pull-tiller. I am talking about a canoe, so this is not a direct translation to a wider boat.

    I have a question and am looking for input on how I am currently running my halyard. I don’t remember where exactly now, but I started noticing in a old illustrations of small lug sails the halyard running from the top of the mast to the bow then back to the mast base or cockpit. Becoming a forestay. I have started doing this and am liking it. The halyard/forestay gives me a nice strong force to set the sail to when I am beating. It is working great, I am out pointing many boats and the sail is setting quite well. One tricky part of it is when raising the sail I have to be careful to to over tension the halyard. As soon as the sail is up, the angled halyard/forestay starts to pull the mast too far forward. It is a fine line, but set just right it is good.

    What is your opinion of this type of halyard running?
    "Yeah, well, that's just, like your opinion man"
    -The Dude-

  20. #20
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    Default Re: standing lug sail yard twist

    Quote Originally Posted by Matt young View Post
    I also have my halyard block athwartship and found it works better for me. Along with the double downhaul made very tight. For me I am liking not having a traveler, my sheet runs up to the end of the boom from a fixed central point, I like that I can center the boom more easily. This works since I have a push-pull-tiller. I am talking about a canoe, so this is not a direct translation to a wider boat.

    I have a question and am looking for input on how I am currently running my halyard. I don’t remember where exactly now, but I started noticing in a old illustrations of small lug sails the halyard running from the top of the mast to the bow then back to the mast base or cockpit. Becoming a forestay. I have started doing this and am liking it. The halyard/forestay gives me a nice strong force to set the sail to when I am beating. It is working great, I am out pointing many boats and the sail is setting quite well. One tricky part of it is when raising the sail I have to be careful to to over tension the halyard. As soon as the sail is up, the angled halyard/forestay starts to pull the mast too far forward. It is a fine line, but set just right it is good.

    What is your opinion of this type of halyard running?
    I think that it might be one of the many Victorian experiments. No reason why it should not work if the yard does not project far enough forward to foul it when coming about.
    It really is quite difficult to build an ugly wooden boat.

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  21. #21
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    Default Re: standing lug sail yard twist

    A couple of observations:
    The 'dipping line' is something that appears on the International 12 (see Small Boats Annual 2016) and is actually two lines with trapeze handles on the ends. A quick pull after tacking, moves the heel of the yard from one side of mast to the other. Much simpler than handling a full blown dipping lug.
    The halyard led to the stem head, as a forestay, is exactly the arrangement described in Swallows and Amazons, as the Walkers rig Swallow for the first time. If a mast is bending forward with halyard tension, and aft with that of the sheet, then maybe a stiffer mast is required. On our balanced lug rigged Welsford Truant, we have a carbon fibre mast, which is extremely stiff. The depowering flex in the rig, comes about through the yard.
    Dave

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    Default Re: standing lug sail yard twist

    Yes Dave me 2 piece wooden mast is pretty bendy. Maybe at some point I’ll make a new one??
    Nick yeah no problem with the yard fouling on the halyard.
    thanks guys
    "Yeah, well, that's just, like your opinion man"
    -The Dude-

  23. #23
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    Default Re: standing lug sail yard twist

    Thank you all for your wisdom. Sounds like my best path is to keep the options open and try different set-ups. I'll start with halyard running athwartships and forget the dipping for now.

  24. #24

    Default Re: standing lug sail yard twist

    Quote Originally Posted by johndowney View Post
    Hi folks...Glad I found this thread though here we are in 2020. Great information on here relevant to my current situation so I’m hoping all you smart builders are still around. (I’ve frequently referred to the well-documented EZ Duzzit blog during my own P.14 build.) “Connie” is just about ready to get her feet wet, though at this self-isolating time she may have to get mounted on the wall instead. I’m just finishing up construction of the spars for my standing lug rig and decisions need to be made. Yesterday I made a really nice little mast collar as shown in the plans for the boom jaws to nudge up against. I didn’t attach it yet and after reading this thread it seems like it may be unnecessary if I rig a down-haul as I intended. True? Another question is whether the masthead halyard sheave run fore/aft or athwartships. Arch Davis suggests a dipping line attached to the heel of the yard and I like that idea. (I have history in the home of Beer Luggers from Devon, U.K. Where the “dipping” lug is traditional, albeit an entirely different kettle of fish so to speak, as the tack is hauled around the mast and re-attached forward.) If I rig the dipping line the halyard will need to fun fore/aft. Any thoughts? Does dipping work well on this small rig?
    Sorry for this long-winded post, but I have time on my hands during the quarantine.
    Thanks all.
    You are correct. With a good downhaul you will not need that boom jaw stop.

  25. #25
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    Default Re: standing lug sail yard twist

    Quote Originally Posted by johndowney View Post
    Thank you all for your wisdom. Sounds like my best path is to keep the options open and try different set-ups. I'll start with halyard running athwartships and forget the dipping for now.
    You can forget the dipping for ever. Tests have shown that a standing lug is as efficient on both tacks with the sail "aback" or not.
    It really is quite difficult to build an ugly wooden boat.

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  26. #26
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    Default Re: standing lug sail yard twist

    The Int 12 guys dip their yards, and if the most popular lug class is doing the wrong thing it would be interesting to know it.
    Last edited by Chris249; 12-02-2020 at 01:58 AM.

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    Default Re: standing lug sail yard twist

    Quote Originally Posted by Chris249 View Post
    The Int 12 guys dip their yards, and if the most popular lug class is doing the wrong thing it would be interesting to know it.
    They are overthinking it and are not aware of the data that I found.
    The observation is supported by some work done on why a fly's wing works. The wing of a fly gains its strength from each alternate vein being either above or below the chord line of the wing. That means that the wing is corrugated, and is not a smooth curve. However, the air flows over it as though it were a smooth curved surface, each valley being filled with dead air. It is most likely that the air flow over the sail, creased by the mast, is the same.
    It really is quite difficult to build an ugly wooden boat.

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  28. #28
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    Default Re: standing lug sail yard twist

    Well, my first version of the post started with "What data?" but it sounded too peremptory. Whether a fly's wing is similar in operation to a sail would seem to be an interesting question; the reynolds numbers (about 10 versus up to 10 to the 7th power for sails as I understand it), angle of attack (35 degrees for insects versus something like 19 for sails normally) and consistency of flow (intermittent with hysterisis versus fairly constant) seem to be very different.

    It's quite possible that there is very little difference with the yard dipped each tack; for the top Int 12/12 Voetsjoel/12 Foot Dinghy sailors, even a couple of metres over a mile may be critical and that is difference is unlikely to be demonstrated in many tests. Of interest, though, WB Sails' CFD predictions show that an Optimist sprit on the leeward side reduces drive (lift) by 5%.

    One would think it unlikely that the thousands of Int 12 sailors who have used tripping lines (aka "reins", tacking lines or tweakers) are ignorant people who are "overthinking it". Whether that means that dipping is important for leisure sailors is another issue, but I'd be reluctant to criticise the knowledge evolved in over a century of experience in the world's most popular class. Of course, it could be that the members of the biggest standing-lug class have used tripping lines for over a century for no good reason, but personally I think more of them than that.
    Last edited by Chris249; 12-02-2020 at 11:01 PM.

  29. #29
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    Default Re: standing lug sail yard twist

    Nick, I think Chris is right
    In The Netherlands the International 12, here we call it the Twaalfvoets Jol, is an active racing class and they all dip their yards with the tripline.
    But Rob Bouma found with the Tirrik, with a balanced lugsail, that she sails better with the yard at the luff side of the mast. His explanation is that the sail twists better then. Perhaps I should build more twist in his sail, but I hesitate to experiment here. You can see the boat sail via his site. www.jachtwerfdezeeg.nl. Frank
    www.oarandsail.nl

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    Default Re: standing lug sail yard twist

    Quote Originally Posted by FF View Post
    Nick, I think Chris is right
    In The Netherlands the International 12, here we call it the Twaalfvoets Jol, is an active racing class and they all dip their yards with the tripline.
    But Rob Bouma found with the Tirrik, with a balanced lugsail, that she sails better with the yard at the luff side of the mast. His explanation is that the sail twists better then. Perhaps I should build more twist in his sail, but I hesitate to experiment here. You can see the boat sail via his site. www.jachtwerfdezeeg.nl. Frank
    www.oarandsail.nl
    The thread is about standing lugs, not balanced lugs that have a significant amount of sail forward of the mast.
    It occurs to me that the psychology of racing might mean that crews dare not be different from their competitors, just in case.
    It would be easy to set up a test with modern accurate GPS.

    Looking at that sail plan, i am really surprised that dipping gives any benefit, but a jerk on a line would trip the throat with ease.
    It really is quite difficult to build an ugly wooden boat.

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