Biplane Planing Hull?

Discussion in 'Boat Design' started by Rurudyne, Apr 2, 2015.

  1. Rurudyne
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    Rurudyne Senior Member

    On a complete lark I was cruising through some old magazines and I came across a reference to a "biplane planing hull" plans in an old Polular Science: https://books.google.com/books?id=XSgDAAAAMBAJ&lpg=nl&pg=PA76#v=onepage&q&f=true

    A quick description from the article:
    On encountering this thing I had two principal thoughts: firstly that the intent here seems to be for a hull that stays more or less level when on plane; second that it reminded me, on account of the claim of relieving pressure, of modern designs which provide for air cushion amidships ... not that that was the intent of this thing but that it is principally separated from them mainly by the addition of pushing pressurized air under the hull.

    And of course if anyone still writes about this kind of hull it isn't showing up with google as "biplane" anything (though I did learn the Italians built a 9-wing flying boat in 1921).

    So in hopes of learning something, and maybe sparking a little discussion about the perceived merits/demerits of such a hull, I want to ask what the type may be known as at this time and also to inquire of opinions about the likely characteristics, from either literature or opinions from folks based on them looking at the plans in the above link.
     
  2. tom28571
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    tom28571 Senior Member

    I use a similar kind of hull design although I keep the keel level so that there is no hollow involved. The idea is to hold the bow down to promote early planing as well as increase longitudinal stability. It is a three point lifting surface comprised by the usual high lift forward sections and the aft wide chines having a positive angle longitudinally and negative angle laterally. Walt Schultz has his inverted V hull that is also very similar. He has a patent on it but I don't know what the patent claims are since the basic principle was used earlier by me and now find that others did it long ago. The biplane label is kind of odd.

    I think that low speed drag might be an issue with the one in this post. Weston Farmer is responsible for me getting my ideas with his Trumpet design which looks somewhat hogged like the posted design but is not really hogged at all.

    Thanks for the post. Lots of good stuff that has been forgotten; often because the material or power was not available to make it successful at the time.
     
  3. Rurudyne
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    Rurudyne Senior Member

    Here's a thought.

    It seems that Newcomb Leonarde was professional contemporary of Bruno Beckhard who was mentioned by Weston Farmer in the description of Trumpet.

    Among Mr.Leonarde's contributions to magazines that I found included an article about Outboard Racing Secrets, https://books.google.com/books?id=c...wAw#v=onepage&q=newcomb leonarde boat&f=false , as well as this one about handholds for carrying small boats, https://books.google.com/books?id=0...wBA#v=onepage&q=newcomb leonarde boat&f=false , that give his address as Mystic, Conn.

    I know it's probably not wise to go by an artists interpretation of a boat in motion, like the one found for the plan I linked to earlier, as it could easily run differently (can't assume the designer was responsible for it, can we?), still considering what you wrote maybe Mr. Leonard was thinking "sea sled" with his design if it actually did lift the bow clear at speed?

    Does the rendering in the article seems at odds with the description (as relieving pressure) to you?
     
  4. tom28571
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    tom28571 Senior Member

    I think the rendering is just an artists interpretation and shows the boat in the attitude most people expected a fast boat to take at the time. Its probably not an attitude that would be stable. At the speeds available, I doubt that there was appreciable lift under the hollowed out hull sections so that was probably not a big consideration. I have not spent a lot of time going over these old magazines lately but did so in the past. Older "MotorBoating" magazines are a treasure. Nothing even remotely like them around today.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Rurudyne, can you point me to some examples of "modern designs which provide for air cushion amidships" ? Getting back to this "biplane" boat, my initial thought is getting the bow to rise when the boat is pushed into the back of a wave, could be a challenge. I would expect it to plough, somewhat more than if the hollow had been omitted. But it will probably pop on plane more easily. It may even ride a little more gently, but be wetter.
     
  6. Rurudyne
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    Rurudyne Senior Member

    I think they're called air supported vessel or air step hull. Link ... ah, Bently Yachts ( which it won't let me link to for some reason ) calls it air cavity.

    Basically have a cavity below your hull and pressurize air to fill it.

    Since, IIRC, wave formation is the major player drag wise I'm not sure how much it nets you. Absolutely no idea for planing.

    Hope that helps.
     
  7. Easy Rider
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    Easy Rider Senior Member

    There was in the 70s (about) a group of boat plans that had the same kind of bottom design as this "biplane" boat. They were planing broad (squarish) stern boats that are often called "semi-Dories."

    The plans were by "Captian Bill Orell" in Texas and he called his boats "Texas Dories". Only 15 to 20% were of the hooked bottom design.
     

  8. Rurudyne
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    Rurudyne Senior Member

    Did a quick search. Turns out Peyson bought the rights to the Orrell collection, including designs by Atkins and Bolger.

    One funny thing: whilst poking about I came across a typo in an old post about a skiff with 28' of headroom. One respondant assured folks that even Texans didn't have swelled up noggins that big. :)

    Another guy said he'd told someone, who apparently had made the matching typo, that while he had a 16' wide skiff (presumably to part with) it was only 3' long.
     
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