stepped hulls for trimarans

Discussion in 'Boat Design' started by tugboat, Mar 11, 2009.

  1. Gary Baigent
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    Gary Baigent Senior Member

    "That is just what the steps on aircraft floats are for. Not necessarily to go faster but to break surface tension."

    Ah, hello Tom, what occurs if the seaplane doesn't break tension? It doesn't go fast enough to lift off. The whole concept of stepped hulls is to go faster ... so they can fly.

    Yves Parlier's Hydroplaneur is very interesting, Doug, but it was as hopeless as Greg Ketterman's foiler in light airs. Also it was an absolute ******* in larger seas - and Parlier said sailing the boat was one of the hardest ordeals he'd ever suffered - and he has done some amazing things ... like lifting the broken but self repaired rig on Aquitaine Innovations at Stewart Island, South Island, NZ ... on his own!!!!
    I didn't comment on your spinning stepped float thing ... because it is simply a weird fantasy removed way too far from practicality. How much progress have you made on it?
  2. Doug Lord
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    Doug Lord Flight Ready


    Well, Gary that's interesting-he is a remarkable man. He has also built a new stepped hull prototype using a kite-with the intentions of fitting that on the 60 footer which he has talked positively about in everything I've read that he's written. If you have a link or copy of comments of his to the contrary I'd sure like to see them.
    In his first website on l'hydraplaneur he described that he recognized that some sort of variable geometry was necessary to sail such a design in light air-never saw what he had in mind but it inspired me-my spinning, stepped float thing that you say is impractical and a fantasy and weird. I'll agree maybe weird and currently as much a fantasy as any new design but definitely practical. The "Devils Tail Ama" that you named is a direct descendant of design experiments I did with stepped hulls-sort of a stepped hull w/o the step. I still think the ROH concept is viable for larger tri's-hell, if mono's can cant a keel that is 60% or more of the weight of the boat surely a lightweight ama can be rotated 180 degrees! The current attachment system and hull are much different than the concept model-and better.
    I think you're wrong about stepped hulls-particularly those that are designed with an effective variable geometry system for light air. And so does Parlier....

  3. tom28571
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    tom28571 Senior Member

    I think maybe we are saying the same thing but also think that somewhere in my aviation reading that the steps were the solution to breaking from the surface even though the plane would not lift off at the same speed without steps.

    Anyway steps are not a good thing on a sailboat except for high speed.

  4. Gary Baigent
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    Gary Baigent Senior Member

    Why is it that you are so nauseously condescending ... repeating stuff that I've read earlier, or long time knew about it, as if it is a new, unknown, revelation coming from the Lord's mouth?
    Yes, variable geometry hulls like Hydroptere sp is a way around the major stepped hull disadvantages ... but fixed stepped hulls are a complete and utter disaster.
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