Small asymmetric power cat

Discussion in 'Boat Design' started by rosbullterrier, Jan 21, 2010.

  1. rosbullterrier
    Joined: Feb 2005
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    Location: Cornwall, UK

    rosbullterrier Junior Member

    I'm building a 4mtre cat for small twin Seagull engines. The deadrise is shaped to rise in the water but not plane.
    After reading possibly every opinion reg the virtues of flat vertical inside hull sides, I still have not found what this configuration would do to the steering or speed and what the hull spacing should be - for this application.
    Would there not be any bow wave between the hulls?
    Thanks gents . . .
    ps the motors are to be situated mid (through) hull, behind each crew.
     
    Last edited: Jan 24, 2010
  2. jonr
    Joined: Sep 2008
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    jonr Senior Member

    I'd think in terms of two racing sculls connected together at whatever the min recommended width is. Isn't it 19.5 degrees off the bow?
     
  3. rosbullterrier
    Joined: Feb 2005
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    Location: Cornwall, UK

    rosbullterrier Junior Member

    Oh dear ,nobody interested - I did put it in the catamaran department - it got moved!

    Does it fall between stools - not big enough as a power boat and unlikely for Seagull racing . . .

    All I need to know chaps is whether there are bow waves at speed up to say, 15mph, between the hulls if they are straight vertical sided.
    Certainly I can, and will , build it and experiment, I'm just trying not reinvent a wheel or have to repeat your valuable experience!
    If it were a planing boat it wouldn't matter; its the possible wave resistance to determine the possible benefit of vertical inner hulls . . .
     
  4. Jeff
    Joined: Jun 2001
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    Jeff Moderator

    I'm sorry - we currently have one powerboat forum and then the sailboat forum divided into monohulls (sailboats forum) and sailing multihulls (multihulls forum) - but we don't yet have a separate forum for power catamarans. I saw outboards, and thought powerboat, but you're right, not quite the right place for it to be noticed. Let me move this thread one more time to the boat design forum and see if we can get some better response for you.
     
  5. sabahcat
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    Location: australia

    sabahcat Senior Member


  6. rosbullterrier
    Joined: Feb 2005
    Posts: 83
    Likes: 2, Points: 8, Legacy Rep: 21
    Location: Cornwall, UK

    rosbullterrier Junior Member

    Sabahcat - the very man - I was just about to find how to send you an email.

    I was very impressed with your duflex 10', 'small powercat dinghy'. It would appear exactly what will work for me, you were inspired. I am very embarrassed to have copied the assembly without paying you - most others want money for their designs . . .

    Would it be a cheek to ask you the very question for which I'm searching - what is the advantage of the flat straight hull side in your asymmetric design? You've made and tried it, does it remove the bow wave and allow the hulls to be closer together?

    Yes, thats the Seagull engine. Shiney one you've got there.
    I'm placing the Seagulls through the hull floors half way back. The steering will be interesting . . .
     
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