Horizontal paddle at front of hull?

Discussion in 'Multihulls' started by InetRoadkill, Jul 20, 2019.

  1. InetRoadkill
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    InetRoadkill Junior Member

    I can't find an example pic, but I remember seeing some Polynesian outriggers with horizontal spade paddles on the bow. They were pitched up with the apparent intent to lift the bow when deeply piercing a wave. I'm curious why this feature doesn't appear on modern multihulls, or perhaps as a modified strake form.
     
  2. Manfred.pech
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    Manfred.pech Senior Member

  3. InetRoadkill
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    InetRoadkill Junior Member

    That's the same idea, but a different culture than I remember. I've been sitting here thinking about and I'm guessing the same effect can be achieved with a chined hull. But it would be nice to have a fine entry. One concern I had about having a spoon is that if you pitched down and really buried the bow, the spoon might act more as a brake rather than lift and aggravate a pitchpoll situation. Though I suspect if you did bury that hard, you're already in trouble.
     
  4. upchurchmr
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    upchurchmr Senior Member

    That paddle or spoon will help if you bury the nose exactly the right amount.
    If you get more "dive" its going to force the bow down more than if you just had the bow.
    If you really think you will get enough force to submerge the bow, the next worse thing you can have is an open bow.
    At least with a deck, some of the water is going to shed off the sides.

    I don't know enough about "native" style boats, but if you were on a small daysailing catamaran, I think the very best is a narrow deck with a rounded top.
    Of course not too narrow or you loose the bouyancy to save you when you are just on the edge of diving. Everything is a trade off of course.
     
  5. Clarkey
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    Clarkey Senior Member

    The Proa 'Cheers' fitted 'anti dive plates in an attempt to reduce bow burying. I don't know how effective they were.

    [​IMG]
     
  6. upchurchmr
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    upchurchmr Senior Member

    Obviously Cheers needed some help with the strakes and then the plate.
    The book Cheers talked about concerns due to the very low freeboard forward.
    But apparently during the OSTAR race the conditions never caused it to be necessary. And the conservatism of the sailor.
     
  7. trip the light fandango
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    trip the light fandango Senior Member

    I think W17 Designer showed a picture of a set of upward angled plates on the inside bows of a 1950's cat. I've been toying with the idea of making a set similar[outside bows with an eye painted under each lid..err] that were hinged[and sprung..?] so that any downward force on the plate could close the flap. But the water pressure under the flap /plate would have to be less for it to work. It wouldn't be hard to make, testing it on the other hand could be a little problematic,..ha .
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Commonly seen on competition surf skis...….
    surfski.jpg
     
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  9. upchurchmr
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    upchurchmr Senior Member

    The Shark catamaran had angled strakes on the bows - that was designed around the 60's.
    [​IMG]
     
  10. InetRoadkill
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    InetRoadkill Junior Member

    The anti-dive paddle seems good at first, but as mentioned earlier it might work against you depending on the angle of attack against the water. Strakes might suffer the same problem. I could see the cat in the picture above with the flat deck doing bad things if the bow dipped below the surface. (Of course, I don't think that particular boat was really intended for rougher water.)

    The design I'm playing with for grins uses an axe hull up front with a deep chine on the outside. The forward top 1/3 of the ama is peaked and narrow on the deck to slip thru the water to reduce plowing should it enter a wave at a bad angle. The trick I see is to balance enough reserve buoyancy up front to keep the bow above water without a lot of unwanted pitching.
     
  11. upchurchmr
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    upchurchmr Senior Member

    If you are on a daysail catamaran, the way to keep the bow out of the waves is to move your weight back.
    Might not work well on the boat initially shown, since the biggest problem might be waves when comming into a beach or harbor.
    What do I know.
     
  12. InetRoadkill
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    InetRoadkill Junior Member

    Actually, I'm thinking just a bit bigger. (45ft +/-)
     
  13. Manfred.pech
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    Manfred.pech Senior Member

    IR, I´ve tried hard to find anything with "horizontal spade paddles" in CANOES OF OCEANIA (three volumes) from Haddon and Hornell, POLYNESIAN SEAFARING from Edward Dodd and some more. But I didn`t succeed.
    Can you please help me and make a small sketch or tell me, where I can find more? Thanks in anticipation.
     
  14. upchurchmr
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    upchurchmr Senior Member

    Are you going to put enough sail area on this boat idea for you to need something like the "paddle"?
    Do you have any information that that size boat has a problem with pitchpoling?

    I'm not aware of an issue, but I'm not looking to build something that big - so I haven't looked.

    Perhaps I missed it, but what kind of a boat are you wanting to build?
    Catamaran, Trimaran, Proa, or monohull?
     

  15. InetRoadkill
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    InetRoadkill Junior Member

    The picture posted above of the kayak-style boat posted above is a good example.

    The boat I'm sketching is a modified blue-water trimaran form somewhere in the neighborhood of 45 feet. The bow paddle was just a thought and I was curious why they are not common. I came to the conclusion that the same effect could be accomplished via strategically placed chines which would have the advantage of not working against you should the nose get buried deeply into a wave at a terrible angle. I'm not really too terribly concerned about pitchpolling since this is not a racing boat concept. But it would be a nice safety feature easily incorporated.
     
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