Low powered. planing tinny copy

Discussion in 'Boat Design' started by Horsley-Anarak, Aug 17, 2014.

  1. lewisboats
    Joined: Oct 2002
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    lewisboats Obsessed Member

    1/4" ? Sure... it flexed like a drum head. Never caused any problems though. I didn't put any stringers or strakes on the bottom and those would probably have stiffened it up a bit. Still, that thin of material is going to flex when you start pounding on it. Yours does look nicer... especially as mine is land fill material :(
     
  2. Horsley-Anarak
    Joined: Jan 2009
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    Horsley-Anarak Junior Member

    Sorry I did not intend to be rude.:eek:

    I found that a couple of 7/8" stringers/strakes took a lot of the rippling out of the floor.

    H-A
     

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  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Steve can you post some photos of your boat up on plane at speed? It's performance is about as I've been suggesting for this one, but I'd like to see it's trim angle.

    Flexing isn't a bad thing, unless you let it get out of control. Look at it this way, would you rather get a whipping by a baseball bat or a Nerf baseball bat.
     
  4. lewisboats
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    lewisboats Obsessed Member

    Sorry... I never got any pictures of it up on plane. I do remember that it really flattened out after it came out of its hole. With all that weight in the back (that full seating area, the motor, 6 gallon metal tank and 190 lb me0, it trimmed down by the stern quite a bit at rest but actually seemed to be less so at speed.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Steve was yous warped or pretty much monohedren? It looks like you maintained the deadrise as best as you could, but I'm guessing.

    Warped bottoms tend to rise up more, climbing out, while monohedrens tend to start with more squat and rise uniformly, though there can be a transition point, which you might have just described, but I'll bet it was just the static CG being so far aft, which sorted out once your contact patch settled down. This isn't always the case. You can design a monohedren to take a set, then hold it throughout most of it's operation range. At the very top end it starts to bow up again, but you're on the edge of longitudinal instability at this point anyway. My 30' mono racer does exactly this, taking a 3 degree set and holding this until about 85 MPH, where she starts to rise. I worked the chine hard to get this particular attribute.
     
  6. lewisboats
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    lewisboats Obsessed Member

    The aft 5/8 or better of the boat was all the same deadrise of 10 degrees. It increased slightly the rest of the way forward to give a slight keel advance/chin. Once it got going the slight warp up front was taken out of the picture. If I had known then what I know now I would have put a 1/2" hook into about 4 ft long ending about 4" forward of the bottom of the transom. Sort of a slight trim tab built into the hull. It might have knocked a mile an hour off the top end but I think it would have helped with acceleration a bit and gotten the bow down quicker.
     

  7. Horsley-Anarak
    Joined: Jan 2009
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    Horsley-Anarak Junior Member

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