Power cat with sail hulls

Discussion in 'Multihulls' started by 2farnorth, Dec 18, 2008.

  1. 2farnorth
    Joined: Oct 2008
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    2farnorth Junior Member

    Hi to all,
    Is it feasible to use the hulls of a sailing cat in a power application? I do not want to plane, but was wondering about weight distribution and such. I assume I would just want to keep the weight centered and just aft of amidships? I want to build a trawler type cat, nothing fancy, just simple and reliable. Or is this a stupid question and I should just go back to my room.
     
  2. Manie B
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    Manie B Senior Member

    What size?
    aplication?
    power / speed requirements?

    maybe we can get a better idea of what you are planning:D
     
  3. 2farnorth
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    2farnorth Junior Member

    36-40 foot, electric propulsion with a large solar array (see "SUN21") with a generator backup, 6-8 knot cruising speed, liveaboard for my wife and I.
     
  4. sabahcat
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    sabahcat Senior Member

    Yep, that should work as it should have worked when it had a mast on it (assuming the original hulls would motor at around 6-8 knots)


    This is, I believe, what Gen 1 French powercats basically were from the big production yards as they already had the moulds.

    I am doing a similar thing with diesels, and in the last 15% of the hull, started pulling the underwatershape down so as to have a horizontal flat about 200mm underwater in the last 5 feet of boatlength to help prevent any tendency to squat in the 10-14 knot (max) range
     
  5. 2farnorth
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    2farnorth Junior Member

     
  6. sabahcat
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    sabahcat Senior Member

    Ermmm, I found low speed powercats that were in production with similar hulls and displacement, that worked, then errmm, massaged their styling and cabin/ bulkhead positions somewhat to suit what I want.

    I justified the moving the cabin Forward, 400mm from original sailing position, to be balanced by the slightly heavier engines.

    I justified the extra cabin, engine and diesel weight by the lack of rig and winches and making boat 24 feet wide instead of the 28ft in sail format
     
  7. 2farnorth
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    2farnorth Junior Member

    sabahcat, sounds like if I justify everything in my head, she should float right on her lines:D No, I know what you mean. I think maybe I am over thinking this whole deal....I just need to build it and be done with it.
     
  8. Nolan Clark
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    Nolan Clark Junior Member

  9. Steve W
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    Steve W Senior Member

    What sailing cat hulls do you have in mind? I assume you are thinking of using some existing hulls.If you go to Malcom Tennants website and read some of his articles you will find that he uses sailing cat hull shapes for powercats under about 10 meters. I see you just a few hours away from me.
    Steve.
     
  10. 2farnorth
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    2farnorth Junior Member

    Nolan, thanks for the link, very informative. Those hulls would work perfect for the next 10 years as we will be restricted to week-end and short vacation cruising on the rivers up here in Minnesota/Wisconsin.

    Steve W, I was looking at K-Design 860 because of the price of the plans and hoping to be able lengthen the hulls.
     
  11. MarboMan
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    MarboMan Junior Member

    Check out PDQ Yachts.

    The main problem that you will run into is in rough to moderately rough conditions, the props will be lifted out of the water.
     
  12. sabahcat
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    sabahcat Senior Member


    This ?

    http://www.ckdboats.co.za/kd860.asp

    I'd be inclined to something like the pic if it was me (this is a KD860)
     

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  13. Ernie Travers
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    Ernie Travers Junior Member

    Hello 2farnorth,
    basically the answer is "NO"
    A lot of professional builders have done that with disastrous results, although they never realise it.
    If you want to go over 11 knots, you should have planing hulls. Then you get efficiency. Displacement hulls only work on big long power catamarans.
    Light weight good design is critical. Then you experience pleasure.
     
  14. 2farnorth
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    2farnorth Junior Member

    Hey Ernie, thanks for the reply, I ahve been off the thread for a while. I am not looking to go fast, If I got 10 knots out of a twin electric motor setup I would be happy. Does that change your opinion?
     

  15. PortTacker
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    PortTacker Junior Member

    Im my opinion not a good example. The hulls are very flat aft and at any speed just dig and squat.
     
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