What Wood To Make A Rudder Out Of?

Discussion in 'Sunfish Talk' started by andyatos, Jan 4, 2017.

  1. andyatos

    andyatos Active Member

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    I'm going to make a vertically oriented rudder for my Sunfish. The standard for wood rudders seems to be mahogany but I'm guessing that any tight grained, strong wood would do, right?

    Anyone ever make a Sunfish rudder out of something other than (more expensive) mahogany?

    Thanks,

    - Andy
     
  2. fhhuber

    fhhuber Member

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    Mahogany is used because it is resistant to rot, meaning you don't have to replace the rudder blade as often.

    Regardless of what treatment and finish process you use on the wood, it eventually gets moisture inside and will rot out. Poplar would work fine for a while, but won't have the 30+ year life in active use that a mahogany rudder would have.
     
  3. Alan S. Glos

    Alan S. Glos Active Member

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    I agree. Mahogany is the wood of choice, light, strong, rot resistant and "takes tools" nicely.

    Alan Glos L1020371.JPG
     
  4. Webfoot1

    Webfoot1 Active Member

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    Any hardwood will work however White Oak is the most commonly used
    nautical wood for sailing ships of yore. Check out you big box store and see
    what sizes they have. I've used White Oak and Mahogany with no problems. If you
    keep a nice thick coat of spar varnish on and store in a dry place your rudder
    should last almost indefinitely. I guess you could use a figured-hardwood if
    cost is no object. It you want something to brag about you could make one
    out of Teak although it would take some real effort to shape it.
     
  5. andyatos

    andyatos Active Member

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    Thanks guys!

    - Andy
     
  6. Wavedancer

    Wavedancer Upside down? Staff Member

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    Not sure if this is relevant, but about ten years ago, the Class had a long 'discussion' about introducing a more vertical rudder blade. A few test blades were made and passed around among Class members. Many liked the more vertical blade because it made the boat easier to handle in heavy breeze. Ultimately though, the new design was not approved because of the cost. The class officials really wanted to keep the cost of Sunfish racing to a minimum.
    The discussion was on this Forum, but is currently 'hidden', I think.
     
  7. andyatos

    andyatos Active Member

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    Yup, that's exactly why I'm doing it. I did the same thing 30 years ago to an old, beat up Sunfish I had back east. Made a huge difference.

    I also made my current Laser rudder vertical.

    - Andy
     
  8. Webfoot1

    Webfoot1 Active Member

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    You might be able to get the same benefits by simply making the rudder a few inches
    longer. It would allow you to use the same mounting bracket with no changes.
     
  9. Roller

    Roller Member

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    The Laser rudder foil/profile is no doubt more efficient than the Sunfish rudder--although, of course, not Sunfish Class legal. rudder_w_laser_dimensions.jpg
     
  10. fhhuber

    fhhuber Member

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    You do know that just drilling another pivot hole, closer to the leading edge of the rudder would allow it to swing more vertically...

    If you have a stock wooden rudder you could add a piece to the top front corner and cut it appropriately for the desired angle and new hole location. Just need a small piece of wood and a couple of dowels.
     
  11. chris williams

    chris williams Member

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    These pictures show where to drill holes to make the stock blade much more vertical. This would have been a possible route to a more vertical rudder instead of coming up with a totally new blade. The red arrows point to the existing holes in a normal blade, whereas the blue holes point to the holes to be drilled to make the blade more vertical. The other pix show the rudder cheeks in position for the new more vertical setting and in position for the "current" setting.

    The vertical blade that was proposed was based on using a piece of wood similar to the current sized piece. It failed to get support from the class due to the expense, with the Central and South American countries being particularly opposed. The blade also had a serious, unexpected problem. That is, when sailing in weedy conditions in a breeze, the weeds wrapped around the blade and did not shed. The problem was they caused so much drag that the rudder popped up. To make the vertical blade work in weedy waters, the springs would have needed to be changed. The manufacturer of the boat didn't want to mess with success, as the boat has been successful since the '50s with the swept back rudder, and the expense of fixing the "popup" issue was unknown. The 2013 NAs at Brant Beach and upcoming Worlds in 2017 could not have been sailed at Brant Beach with the vertical rudder unless the springs were revised. It is a weedy, windy venue - and one of the most fun places I have ever sailed.

    Multiple holes with labels (2).JPG Multiple Holes set for Current 3.jpg Multiple Holes set for New (2).JPG
     
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  12. fhhuber

    fhhuber Member

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    If you just want to "play with it" ... you can just use plywood and treat it with 2 parts mineral spirits, 1 part linseed oil, 1 part spar varnish. Apply heavily and keep applying more every hour or so until the wood quits absorbing it.

    It will last a couple of years.
     
  13. Light and Variable Winds

    Light and Variable Winds Well-Known Member

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    Plywood is kind of "bendy". Epoxy resin (instead of varnish and linseed oil) might make for a lot stronger rudder alternative.

    Is the trouble and expense with plywood "worth the effort" over the "tried and true" mahogany?
     
  14. fhhuber

    fhhuber Member

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    The point of the plywood is to be cheap to see how the different rudder works... you can get a big enough scrap for a couple of bucks. Not intended to last like the mahogany one.

    There were some cheap Snark boats (advertising Kool, Budweiser...) that had ply rudders. Neither the boat or rudder lasted long.
     
  15. Roller

    Roller Member

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    Chris--
    Thank you very much for posting the rudder photos and the accompanying info. Using your pics, stock and rehung rudder angles are compared here (very roughly!). The leading edge of the rehung rudder is about 20° from vertical (as measured in the photo). The LE of a Laser rudder is about 22° from vertical:

    rehung_rudder_compared.jpg
     
    Last edited: Jan 7, 2017
  16. Charles Howard

    Charles Howard Member

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    Andyatos - how strong are the winds you are sailing in?
     
  17. Webfoot1

    Webfoot1 Active Member

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    Being that were are dealing with a lack of surface area in contact with the water,
    angling the rudder may help but be short of optimum. It appears the Laser Rudder has
    both increased cord and an actual airfoil shape. Andy seems to be starting from scratch
    so perhaps adapting the Laser Rudder would be a much better choice. Since the Daggerboard
    is also short of optimum length a later lengthening of the racing Daggerboard might be in order.
    The result would be interesting when put against a race equipped Sunfish.
     
  18. andyatos

    andyatos Active Member

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    Anything from ghosting along in mirrored water to 25+.

    Got a 28" by 3/4" by 7+1/4" piece of mahogany today. $13 at Home Depot. When I'm finished the rudder will be vertical with 21 inches below the lower gundgeon on the stern. Almost exactly the same as my vertical Laser rudder.

    BTW, I sail with a 46 inch GRP Racing daggerboard. What a difference from the wooden daggerboards I've sailed in the past. Particularly with the GRP firmly held in the daggerboard case with looped velcro shims. Absolutely zero vibration or hum at any speed.

    Thanks for all the input! :)

    - Andy
     
  19. beldar boathead

    beldar boathead Well-Known Member

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    There is no issue with lack of rudder surface area. Sunfish turn just fine. The idea of a more vertical rudder is to reduce weather helm. However that can mostly be achieved by moving the gooseneck back. Chris W also points out the vertical rudder had a weed collecting problem. Glad someone thought of testing that out!
     
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  20. Webfoot1

    Webfoot1 Active Member

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    My thought was that a larger surface area would reduce rudder deflection
    needed when close-hauled and therefore reduce drag. At some point increasing
    the size of the rudder ever larger would no longer decrease deflection and again
    start to add drag. The key is to find the optimum size while I believe the factory
    was interested in a trade-off between manufacturing cost vs. effectiveness. You
    could still keep the anti-weed rudder angle by increasing the cord and/or aspect ratio.
     

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