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Thread: Barndoor Rudder Conversion

  1. #1
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    Default Barndoor Rudder Conversion

    Hi,

    I have a 13 ft. Sharpie (Fisher Drake 13) which I am considering a change of rudder for. It currently has the "barndoor" rudder as per plans. I like how the barndoor does not have to kick up to beach the boat as well as its natural anti-weed-catching function. However, the boat is slow to come about at times and I think that is due to the inefficiency of the long shallow rudder.

    Therefore I am considering building a new high-aspect rudder with a weighted kick-up feature.

    My questions are:

    1. Do you think this new rudder will be an improvement?
    2. Do the size, shape, and angle look about right?
    3. This rudder is about 7" wide fore-aft. I'd like to shape a real foil profile, how thick would you suggest to make the blade? 3/4"?

    thanks in advance,

    John
    Attached Images Attached Images

  2. #2
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    Default Re: Barndoor Rudder Conversion

    A high aspect rudder has the advantave of less helm pressure. But before you go through all that work:

    There are many ways to come about: High aspect boats, especially of serious displacement and deep hull, lose little way in a tack. If tacked slowly they can actually gain a boatlength or two to weather just coasting through the wind's eye.

    Many heavy catboats and light cat rigged skiffs, on the other hand, lose way quickly without the sail's power. I mostly sailed boats that liked a slow tack and had a real problem with Marmalade, often getting caught in irons and having to back my way out of a missed tack. Marmalade finally taught me that she wanted to be slammed around. Emphasis on the HARD in "hard alee".

    I think the higher aspect rudder will reduce helm pressure you feel on the tiller but will do nothing to improve tacking.

    So, unless your heart is set on this winter project, get her on the water and try really slamming her from one tack to the other. Might be the very thing.

  3. #3
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    Feb 2006
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    Default Re: Barndoor Rudder Conversion

    Before you make a new rudder, just put an endplate on the existing one. It will make a big difference. About 10 of 12 inches wide will do it , and you'll still have shoal draft.
    -Dave

  4. #4
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    Default Re: Barndoor Rudder Conversion

    I would do it...

    (lift is better than drag)

  5. #5
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    Default Re: Barndoor Rudder Conversion

    It will affect balance by moving the CLR forward a tad.
    End plates will increase lift without changing anything else.
    It really is quite difficult to build an ugly wooden boat.

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  6. #6
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    Default Re: Barndoor Rudder Conversion

    I built a kick up rudder on my melonseed as the boat was not very responsive with the barndoor built per plan. The kick up rudder worked but would annoyingly bind on occasion, possibly because of my build. So to get rid of the moving parts, keeping it simple, I went back to the original design and added a 3" wedge. Been happy with it ever since, boat tacks great, there's nothing to bind and it looks like it belongs there.
    Steve B
    Sjogin IIIa
    PAYTON 13' Pea Pod

    RIVUS 16' Melonseed


    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  7. #7
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    Default Re: Barndoor Rudder Conversion

    Sharpie form boats are notoriously poor tacking. The wish to navigate in ultra shallow water led to the design which works well as it was intended. As a fun daysailing boat the sharpie has disadvantages. The long rather narrow hull has a lot of chine immersed in the water which gives it good course holding ability while the single sailor does his work without worrying about the boat, but it also makes the boat slow to respond to the rudder. These boats are unbalasted but depend on being built heavily for stability. The shallow rudder does not help slow tacking either. Most local sharpies have a jib or are the cat ketch variety, both of which help with tacking. A kick up rudder also helps but is not the full solution.

    In short, nothing is going to make a true traditional sharpie tack as well as most other boats.
    Tom L

  8. #8
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    Default Re: Barndoor Rudder Conversion

    All just thoughts below, not an expert on this.

    In thinking about shifting the role of a sharpie from it origin as a workboat to a dayboat. Originally I wonder if it needed to track well while the crew worked, maybe they would set-up up wind and work downwind? Not the back and forth, up and down, pointing high, and general play we do now. I wonder about the skeg, what about cutting it down, more like a modern sailing dingy and switch to a high aspect rudder. Most likely you would need to be on on the tiller constantly, but that's ok. I also wonder about where you weight is, if the stern of this little sharpie is deep in the water when you are tacking.
    "Yeah, well, that's just, like your opinion man"
    -The Dude-

  9. #9
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    Default Re: Barndoor Rudder Conversion

    Quote Originally Posted by Tom Lathrop View Post
    Most local sharpies have a jib or are the cat ketch variety, both of which help with tacking.
    In short, nothing is going to make a true traditional sharpie tack as well as most other boats.
    This. Boats evolved as a complete package, rig and hull together.

    John, have you tried bearing off to pick up speed and then snapping her through the tack? As Matt says, try moving forward a bit, but be careful in case she trips over her forefoot.
    It really is quite difficult to build an ugly wooden boat.

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  10. #10
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    Default Re: Barndoor Rudder Conversion

    You might also consider changing her trim a little with inside ballast. My canoe tacks better with some weight forward, my ketch too.

  11. #11
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    Default Re: Barndoor Rudder Conversion

    Tradition apart,the barndoor rudder isn't the greatest thing.They often have to operate in the swirling eddies leaving the deadwood and don't have much more fairing than a small radius on the corners.The proposed replacement will be a bit skinny with a seven inch chord and I would think nine inches would be more useful.The better foll sections aren't too hard to locate and will determine the actual thickness.something like a NACA 0012 ought to work and unlike the example in post #6 I would tend to keep the leading edge parallel to the gudgeon and pintle to ease the loads.

  12. #12
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    Default Re: Barndoor Rudder Conversion

    Quote Originally Posted by John Meachen View Post
    I would tend to keep the leading edge parallel to the gudgeon and pintle to ease the loads.
    That really will move the CLR forward.
    It is not a coble we are discussing.
    It really is quite difficult to build an ugly wooden boat.

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  13. #13
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    Default Re: Barndoor Rudder Conversion

    Ledger probably knows a thing or two about barn door rudders. Jim?
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  14. #14
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    Default Re: Barndoor Rudder Conversion

    lightning_drawing.jpg

    Here is the Lightning, a good hard chined boat. The skeg is almost gone, the rudder with its swept back positioning might give close to the same CLR as a barndoor. And you can make it kick up.
    Last edited by Matt young; 01-05-2020 at 07:18 AM.
    "Yeah, well, that's just, like your opinion man"
    -The Dude-

  15. #15
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    Default Re: Barndoor Rudder Conversion

    I foiled the barndoor rudder on my Reuel Parker 18' Sharpie. The helm is much firmer and more powerful. And no noise!
    Last edited by leaotis; 01-05-2020 at 03:55 AM.
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  16. #16
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    Default Re: Barndoor Rudder Conversion

    Quote Originally Posted by SBrookman View Post
    I built a kick up rudder on my melonseed as the boat was not very responsive with the barndoor built per plan. The kick up rudder worked but would annoyingly bind on occasion, possibly because of my build. So to get rid of the moving parts, keeping it simple, I went back to the original design and added a 3" wedge. Been happy with it ever since, boat tacks great, there's nothing to bind and it looks like it belongs there.
    I added a wedge to the bottom of a shallow rudder on a traditionally built sharpie (with a jib) and it increased the depth at the leading edge by a few inches. It really improved the feel of the helm, especially when the boat heeled in puffs.

  17. #17
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    Default Re: Barndoor Rudder Conversion

    I would love to see a picture or description of how you did that.

  18. #18
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    Default Re: Barndoor Rudder Conversion

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    When we remember we are all mad, the mysteries disappear and life stands explained.

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  19. #19
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    Default Re: Barndoor Rudder Conversion

    Quote Originally Posted by leaotis View Post
    Very cool Powerpoint. Thank you!

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