Wind steering bow rudder?

Discussion in 'Boat Design' started by Qmaran, Sep 16, 2021.

  1. Qmaran
    Joined: Oct 2019
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    Location: Thailand

    Qmaran Junior Member

    I am working on a center cockpit trimaran design with a sugar scoop back and a dinghy garage under the deck. So nothing can block the stern. All space is needed to launch or retrieve the dinghy.

    Wind steering is something I really need but there simply is no space to put it.

    Unless I move it to the bow and mount it like a kind of leeboard. Obvious advantages would be less blocking of the wind and no need to reverse the movement with gears. The vane could be directly linked to a balanced spade rudder. The Trimaran will be fairly light weight and easy to get sailing balanced so I hope I will not need very strong steering corrections.

    I did a search online and couldn't find any examples or even mentions of similar ideas. So maybe this is a very bad idea. If so I would like to know why?

    I realize vertical movement will be less at the stern which is obviously better but I don't think that disqualifies the idea. Also bow steering makes the rudder more vulnerable but since it is only auxiliary steering that wouldn't really bother me. And a bow rudder is not completely unheard of either. Kayaks, some giant cargo ships and fast proas have them.
     
  2. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    A drawing of what the stern of the central hull is like would help us all to find solutions.
     
  3. clmanges
    Joined: Jul 2008
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    clmanges Senior Member

    A kayak with a bow rudder?! Never seen or heard of that. There is a paddling technique called 'bow rudder', used on 'yaks and canoes. As hardware, though? You're gonna have to show me that. Proas have rudders at both ends because they don't turn around; they shunt, and they pull up the one at the 'front' when reversing direction. Some old junks and a few other sailboats had forward-mounted dagger-boards, but they weren't for steering. Push-barges. Submarines (as diving planes). On big freighters, they're only used when reversing.
     
  4. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Mount the wind vane on one of the cross beams or either one of the outside floats.
     
  5. Qmaran
    Joined: Oct 2019
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    Location: Thailand

    Qmaran Junior Member

    My bad, I stand corrected. An actual bow rudder on a kayak would indeed be quite stupid.
     
  6. Qmaran
    Joined: Oct 2019
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    Location: Thailand

    Qmaran Junior Member

    The cross beam is very high above the water so the forces on the attachment points would be huge due to lever effect. On the ama is getting complicated. Harder to access and you would need two systems because one ama is usually lifted out of the water.

    Instead of finding a solution I would first like to know if there is a problem. The question stands, is wind steering close to the bow mounted on the side of the hull a good or bad idea and why?
     
  7. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    Wind vane steering systems don't work on fast boats. They are non-starters if you want to sail faster than about 7 or 8 knots. And you generally have to design the entire boat around that idea if you plan on using it. It takes priority over everything else. On a nice double ender with a full keel that weighs 20 tons, it can work just fine. On a trimaran, you are going to need a serious programable autopilot and a slew of sensors like the racers use. The yaw forces associated with the amas dipping and rising just can't be handled by normal pilots. You also have to deal with control reversal with gust response. You point down in a gust in a tri. You point up if its a wind shift. The vane steering system can't tell the difference between the two.
     

  8. Qmaran
    Joined: Oct 2019
    Posts: 29
    Likes: 1, Points: 3
    Location: Thailand

    Qmaran Junior Member

    Thanks for the heads up, I wasn't aware of this. Did some quick reading on this and there doesn't seem to be complete consensus. There is consensus that most wind vanes will not work properly. Others say that only vertical axis vanes with trim tab rudder work and still others say that these work in most conditions but sometimes you need to put a reef in to take the edge of or pull a small drogue. I guess I would just have to try. I will have a autopilot for backup anyway so maybe a well tuned vane can do the job most of the time and in some situations where it struggles I can use the autopilot.
     
    Last edited: Sep 17, 2021
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