soliciting opinions about overly tall rudder design

Discussion in 'Boat Design' started by souljour2000, Aug 25, 2009.

  1. souljour2000
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    souljour2000 Senior Member

    I am toying with the idea of turning my lowly Hunter 20 into something similar to a 23-foot Buckler of which many photos have been posted on this site lately(motorsailer forum).
    Besides the obvious major hull additions there are a few serious rudder considerations...basically...I want tiller steering but wheel steering for the outboard motor...other factors include desire for coastal sailing in Gulf of Mexico....
    So this design entails a cockpit that would be above the aft cabin ..visibility forward would be great...but making a sturdy rudder that holds up with all that leverage force in a heavy sea would be a challenge..anyways...
    carbon fiber/epoxy over balsa rudder body?...stainless steel post and struts for sure...kickup rudder still a possibilty?..
    As for the rig we can address that later.. guess it would be rigged similar to Buckler 23... ...but really just want anyone's input on rudder feasibilty for now.click on my project "sketch" below....link to pic of Buckler 23 in ...the blue-colored areas are existing hull minus cabin that currently exists...white colored area is project area...motor would be outboard attached to transom..electric-controlled via steering/instrument console at fore of cockpit...sounds feasible with ALOT of the right engineering...what are your thoughts....hmmm?


    Buckler 23 pic: http://sites.google.com/site/meinbuckler/

    Hunter 20 pic: www.sailboatdata.com/imagehelper.asp?FILE_id=1270
     

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  2. PAR
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    PAR Yacht Designer/Builder

    Considering your experience, based on questions and observations of your previous posts, I'd strongly recommend you leave this as a dream and move on. It's fraught with many difficult issues, no small one being the gross differences in hull volume between the two boats you've listed. In a nut shell the Hunter 20 hull just isn't big enough. The 22.5 might be, but not very likely.

    About the rudder, if you can't see the issue with this, then you really shouldn't be fooling with it (yep, it's that obvious).
     
  3. lewisboats
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    lewisboats Obsessed Member

    Minor understatement
     
  4. souljour2000
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    souljour2000 Senior Member

    I respect your observations PAR...but I think there are some ways it could still work though it would probably involve failure and trial until I got it right. In the new illustration below I think I have gotten the rudder length down under 6 feet to reduce leverage and the fact that there is an ample skeg should help taking some of the turning pressure (sorry..I'm sure there may be standard engineering terms for this).
    The new rudder design would be more like the cockpit sole tillers that sink into the cockpit floor like you see on the 1970's smaller Irwins,i.e., and the tiller handle would have travel via a wide transom slot that came flush all the way down to the deck.
    As far as the boat not having enough displacement I think my boat would not be able to match the Buckler inch for inch/or pound for pound... but could be a scaled down version.
     

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  5. lewisboats
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    lewisboats Obsessed Member

    It has nothing to do with the rudder length except as a symptom of the major problem...consider the location of yourself, the superstructure you are proposing and the locations thereof in relation to the rest of the boat and ask...AM I AND THE EXTRA WEIGHT I PROPOSE TOO DANG HIGH FOR THIS HULL/DISPLACEMENT/BALLAST COMBINATION?

    In other words...It won't work without some VERY serious rework.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Easy Steve, go easy, lest we scare them off.

    Honestly Souljour2000, this is way out of your current scope of comprehension.

    Consider another hull with sufficient volume aft. Again, a Hunter 20 doesn't have it. Hell, it squats with four people in the cockpit, let alone encumbered your contrivances.
     
  7. lewisboats
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    lewisboats Obsessed Member

    OK...Scare into reconsidering...try not to scare off...got it!
     
  8. souljour2000
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    souljour2000 Senior Member

    Hee ..lol....I don't scare that easy...afterall...I spent a few months on Sailnet in the off-topic politics forum..and I wasn't rooting for McCain..though he DOES seem a bit more appealing these days..oops..sorry... to inject any nasty political vibes into the pristine waters of this forum...seriously...as for the ballast problem..maybe I can incorporate some lead into the design of the skeg. I would only be sailing with my 220 lbs and one or maybe both of my kids...probably 450 lbs..true...that is alot of weight up high...the original Hunter 20 displacement is 1700 lbs...I'm thinking of adding chine runners if I were to do this to help with stability...the swingkeel is 400 lb of iron minus all the existing rusty indentations....I'd probably have to have the keel down with anyone more than myself up there though...
     
  9. PAR
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    PAR Yacht Designer/Builder

    More simply put, you don't have the the skills necessary to attempt such an endeavor. You just don't have the grasp on the concepts, principles, engineering and math to approach from a reasonable perspective.

    This isn't to say you couldn't take a saws-all to the deck cap and liner of a Hunter 20, then tack this "burden" onto the yacht. But it is to say, you don't understand why this particular hull form, is so poorly suited for this and because of this lack of understanding, it's very likely people will get hurt, if you venture into water more then knee deep. BTW chine runners will not do a damn thing for you stability and again this is the point, you really don't have the necessary understanding of the principles involved, to have the slightest hope of success.

    Stick with you day job . . .
     
  10. rwatson
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    rwatson Senior Member

    Of course it can be done Soljour!!!!

    Sell the Hunter, Buy a Buckler - sooooo easy, and much cheaper than the conversion plan.

    God Bless you Par - another two, possibly three lives saved. Good "second banana" there LB, you make a good "bad cop".
     
  11. mwatts
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    mwatts Martin

    Maybe an illustration would help him understand our point better :D :

    [​IMG]

    Not intended to be offensive (so please don't feel so). See it as just a lighthearted way to express our concerns. ;)
     
  12. souljour2000
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    souljour2000 Senior Member

    Well...you guys have had some fun...and I have gained some valuable insights.....Nothing is free...
     

  13. mwatts
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    mwatts Martin

    Hope you don't mind... ;)

    It's just too much weight too high up. Even if she would stay afloat you wouldn't be able to sail her...

    But please keep on posting your ideas here. I'm sure this experience has outweighed doing hours of hard labour and putting your beloved ones at risk just to find out it wasn't a very good idea... ;)
     
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