Sheet to tiller steering on a Junk?

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  • 29 Nov 2022 02:29
    Reply # 13006049 on 12983243

    Steve and all,

    As John surmised, I've been too busy to check on the forum lately. I'm onboard now though and quite interested in hearing how your version of mizzen self steering goes. If I understand it correctly, your PVC outer mast will rotate around an aluminum inner mast. Hopefully the friction between the two will be minimal.

    As Len says, please post photos and a report as you gain experience with the system.

    Meanwhile, I've been doing a few minor but important upgrades on Minimus II, our catamaran with mizzen self steering. We hope to be heading out on an extended sail in the Gulf of California beginning in February and will post updates then.  


      

  • 15 Nov 2022 11:00
    Reply # 12989500 on 12988463
    Anonymous wrote:

    Please post pictures as you build.

    Some questions:

    • Will this mizzen ever be used to produce power or is it only used as a windvane? (aside from at anchor)
    • Where do the control lines go? You mention sheets. So does that mean the control lines affect the sheets of your main or was the sheet to tiller idea just the starting point?
    • My imagined answer is that the mizzen is effectively a large windvane so that other torque increasing methods like trim tab or servo-paddle are not needed. In which case, is the sail/windvane going to be more rigid/flat than a driving sail to be more sensitive to angle changes?
    • Any bungee cords to adjust trim involved?

    Sorry, Len, I have almost completed the build, and I haven't taken many photos, but it is so simple, a few photos when it's completed will show everything quite well. I should be able to do that tomorrow.

    To your questions:

    This mizzen will be purpose built as a weather-vane self steering system, with the added benefit of being able to weather-cock the boat at anchor or while "hove to". I deliberately made the sail cut flat and taut to enhance the weather vane effect. I don't need the sail to drive the boat under most conditions, with the only exception maybe when on a downwind run, it might add a little driving power, but it would even then probably be best used in it's self-steering mode to avoid accidental gybes.

    A bit of background. I built the boat with a balanced lug as per the plans, and have now retro-fitted a junk sail. I did employ a mizzen with the original sail, mainly as a balancing-driving sail, and to offer weather-cocking when anchored or "hove to". But the junk sail is at least 40% larger in overall sail area than the lug, mainly due to increased height. So I don't need the extra driving power of the mizzen. I like to take multi-day cruises where I may need to hold a course for several hours at a time. I don't anticipate doing any truly blue-water cruising where I am on the sea for days at a time, but several hours is still a long time. I have successfully used bungee-type self steering in the past, but I have never been able to achieve true course-holding self-steering for more than a few minutes to maybe an hour in very steady wind So this system seems to offer a very cheap and easy to build method of approaching what other wind-vane methods do. (Of course this is yet to be proven!)

    Back to the design. On David Omick's design the control lines go from the aft end of the mizzen boom, through blocks either side of the cross piece, then cross over to opposite sides of the cockpit, through blocks, and then to the tiller. So the lines (mizzen sheets) are alternately activated as the mizzen engages due to directional changes viz-a-viz the apparent wind. The sail only acts to engage the tiller to turn the boat opposite to the alteration cause by the increasing and decreasing wind pressure on the sails.

    My version has the control lines starting from the cross-piece, driven directly from the swiveling outer mast. This eliminates a bit of friction by eliminating one set of blocks on the cross piece. It also allows the cross piece to be aligned parallel to the transom virtually regardless of the wind direction using a simple ratchet clamp and a "clutch disk" fixed to the swiveling outer mast.

    Fixing the mizzen to any given angle as a fixed weather-vane can be easily achieved by cleating the mizzen sheets in fixed positions rather than having them freely running.

    I don't anticipate needing any shock cords or bungees etc. in this design, although it would still be possible to use these as part of the system if desired.

  • 14 Nov 2022 16:30
    Reply # 12988463 on 12987344
    Anonymous wrote:The mast will be two part, with a free swivelling pvc sleeve over an inner aluminium mast. The small mizzen sail will be attached to the outer sleeve so that it is able to weathervane freely unhindered. A fixed disk will be situated at the boom. The cross piece will be situated below the disk, and freely rotating around the outer mast. The control lines will be attached to this cross piece,and not run through to the sail. The cross piece will be attached to the disk via simpke clamps like a dog clutch after the sail is allowed to settle at its resting position after the boat is balanced as much as possible. This way the cross piece will always be fairly perpendicular to the transom at all times, avoiding sharp angles with different frictional and leverage forces on both sides of the system. Also, the sail can be set to hold the boat dead into the wind at anchor as for any other mizzen. 

    Please post pictures as you build.

    Some questions:

    • Will this mizzen ever be used to produce power or is it only used as a windvane? (aside from at anchor)
    • Where do the control lines go? You mention sheets. So does that mean the control lines affect the sheets of your main or was the sheet to tiller idea just the starting point?
    • My imagined answer is that the mizzen is effectively a large windvane so that other torque increasing methods like trim tab or servo-paddle are not needed. In which case, is the sail/windvane going to be more rigid/flat than a driving sail to be more sensitive to angle changes?
    • Any bungee cords to adjust trim involved?
  • 13 Nov 2022 05:53
    Reply # 12987344 on 12983243

    Some of the discussions on various self steering systems are very technical with lots of jargon that I am not familiar with, even after sailing for quite a few years. I understand most of the various methods of sheet to tiller steering, and I have managed to achieve this at times, but it has been a bit hit and miss on my little boat. What appeals to me about David Omick's method is its simplicity and ease of deployment regardless of the point of sail. And I think my adaptation may make it even more simple.

    The mast will be two part, with a free swivelling pvc sleeve over an inner aluminium mast. The small mizzen sail will be attached to the outer sleeve so that it is able to weathervane freely unhindered. A fixed disk will be situated at the boom. The cross piece will be situated below the disk, and freely rotating around the outer mast. The control lines will be attached to this cross piece,and not run through to the sail. The cross piece will be attached to the disk via simpke clamps like a dog clutch after the sail is allowed to settle at its resting position after the boat is balanced as much as possible. This way the cross piece will always be fairly perpendicular to the transom at all times, avoiding sharp angles with different frictional and leverage forces on both sides of the system. Also, the sail can be set to hold the boat dead into the wind at anchor as for any other mizzen. 

    I haven't been able to do any more on it today after a severe storm came through our city yesterday and I now have our daughter and family staying with us for a few days after losing power. 



  • 11 Nov 2022 17:13
    Reply # 12986069 on 12985689
    Anonymous wrote:

    So, today I started my own version of the wind sail self steering system. It's pretty much the same idea, with a couple of customisations. I'll probably have it finished tomorrow, then I'll post some pics.

    and there’s more relevant discussion on the forums a couple of years back 

    https://www.junkrigassociation.org/technical_forum/1493031

  • 11 Nov 2022 09:21
    Reply # 12985689 on 12983243

    So, today I started my own version of the wind sail self steering system. It's pretty much the same idea, with a couple of customisations. I'll probably have it finished tomorrow, then I'll post some pics.

  • 10 Nov 2022 19:21
    Reply # 12984888 on 12984471
    Anonymous wrote:

    Steve,

    I refer you to the discussion on the Technical Forum between 2 and 13 Feb 2022. I am happy with the method I discussed there, but I have been wondering if anyone has heard from David Omick on the subject. He was going to try my idea with one of his sails. I have two possible answers for his lack of feedback. 1. He is too busy having fun. or 2. It did not work for him and he is being polite in not canning it.

    I am happy to discuss it in more detail if it would help.

    John Pennefather


    I spent a few hours last night reading David's instruction guide and getting my head around the concept and details, and I think I understand the principle well enough, and I have some concepts forming as to how to adapt it to my boat. I think I should be able to knock one up, but it's nice to know that the method has some following here. 
  • 10 Nov 2022 09:01
    Reply # 12984487 on 12983243

    A YouTube search turned up a series of videos by David Omick on his wind vane self steering system. I obviously didn't know you were behind it, but it looks like a very good system for junk rigs, especially because of the more complex sheeting arrangement on junks making it a bit harder to set up a more standard system. I have printed out a detailed set of guide notes he has published that shows the system in great detail. I intend to study those over the next week or so and will probably build a similar system for my boat. I already have a demountable mizzen but it isn't really positioned ideally for use as a wind vane, but it would be quite easy to replace. 

    http://omick.net/adventure/mizzen_self_steering/mizzen_self_steering.html


  • 10 Nov 2022 07:51
    Reply # 12984471 on 12983243

    Steve,

    I refer you to the discussion on the Technical Forum between 2 and 13 Feb 2022. I am happy with the method I discussed there, but I have been wondering if anyone has heard from David Omick on the subject. He was going to try my idea with one of his sails. I have two possible answers for his lack of feedback. 1. He is too busy having fun. or 2. It did not work for him and he is being polite in not canning it.

    I am happy to discuss it in more detail if it would help.

    John Pennefather


  • 10 Nov 2022 06:43
    Reply # 12984444 on 12984071
    Anonymous wrote:

    Not an answer to your question, but I would LOVE to hear more about your Michalak junk conversion. I'm thinking about converting a similar length boat (Dave Carnell's Nutmeg) and I'd love to hear how it has gone.

    If you are on Facebook, search for Michalak Blobster group. I have posted some info there. 
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