Pacific catamaran outboard conversion

Discussion in 'Boat Design' started by WillyOcean, Jan 1, 2026.

  1. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    P Cat is a better candidate for motorizing than some other sailing cats, due to higher flotation in the stern, but is also starting out on the heavy side, which is not great since you are anticipating additional structures as well.
    For putting around in the canal, you can get away with almost anything, but if you’re venturing out of the inlet, design becomes much more important.
     
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  2. WillyOcean
    Joined: Dec 2025
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    Location: Carnation

    WillyOcean Junior Member

    Does anyone know of pictures of a motorized P Cat?
    Would be even better with single center outboard moved back. **** in tbe dark I have to ask

    also interested in someone to weld aluminum in the eastside of Oahu.
    Also interested in some one who does glass work. Thinking it maybe nice to drop the boat off somewhere and get some of the bulk glassing done.
     
  3. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Have you though of splitting her in the centre, where there is basically a "constant" section", and then adding a new bit, around 500mm or more to lengthen the boat, blending the fore and aft sections together smoothly?
    Like so:
    upload_2026-1-5_10-38-10.png

    This adds buoyancy and adds waterline length = lower resistance.
    It also helps with your trimming and slightly better seakeeping too.

    Just a thought...
     
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  4. WillyOcean
    Joined: Dec 2025
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    WillyOcean Junior Member

    I have not really considered that. Kinda scary. I’ll add it to the list of ideas to add float.
     
  5. kapnD
    Joined: Jan 2003
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    kapnD Senior Member

    This catamaran was low on flotation, the “half pipes” were added to both sides of the hulls and faired in.
    Not sure how successful that was, it has not been in service for years.
    upload_2026-1-5_14-1-10.jpeg
     
  6. WillyOcean
    Joined: Dec 2025
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    WillyOcean Junior Member

    I could see that working. That look like it was a cool boat during its time. I wonder what stopped it from going out in the water. Before the jungle made claim.
    Any good parts worth salvage for my project?
     
  7. kapnD
    Joined: Jan 2003
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    kapnD Senior Member

    That was on Craigslist a while back, somewhere in Waimanalo.
    I was impressed by the ingenuity, but have no details, and never got around to looking into it any deeper.
     
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  8. HelmutSheina
    Joined: Dec 2025
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    Location: New South Wales

    HelmutSheina Junior Member

    Gary Dierking the outrigger canoe designer converted an old tornado sailing cat to outboard with something like a flybridge moulding for some shelter at the front. I think this is the one.
     
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  9. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Senior Member

    The most important thing is to keep anything you add as light as possible by using lightweight materials, to keep the boat balanced by offsetting the placement of heavier items, and try to make stuff multi-purpose like cooler as a seat, etc.

    If you are set on moving the motor back, easiest would be an aluminum crossbeam with some clamps with netting filling the area between the current crossbeam and the new aft motor mount crossbeam. Alternatively you could incorporate some drop-in plastic bins in the are between aft beams to store stuff in.

    A great material for small conversions like this that is light and ridged and will hold up well in to our UV is plastic table tops from folding tables, chairs, etc…

    It’s strong enough to use as a platform to stand on with minimal under tubular support, works great for seats, is easy to clean, etc..
     
  10. WillyOcean
    Joined: Dec 2025
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    Location: Carnation

    WillyOcean Junior Member

    This is awesome soo perfect. Thank you for the replay and video. Do you know the length of boat? What length hulls where used? Look like it’s about the size of my P-Cat 18

    do you think the owner/operator like their motor placement?
     
  11. WillyOcean
    Joined: Dec 2025
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    WillyOcean Junior Member

    I love it. that is plan I have netting for the front and back. Buddy has a mast from a hobie that I plan to mound on the bow and stern area that doesn’t have a motor mount.
     
  12. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Senior Member

    Although my conversions have been designed to accomplish tasks that aren’t fishing focused like yours, you might still find some inspiration in them.



     
  13. HelmutSheina
    Joined: Dec 2025
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    Location: New South Wales

    HelmutSheina Junior Member

    Certainly plenty of precedents for that procedure.
    You are most welcome. Pretty sure the hulls are Tornado, an early plywood racing cat.
    TORNADO CATAMARAN - sailboatdata https://sailboatdata.com/sailboat/tornado-catamaran/

    This is Gary's blog, he is eminent in the fields of boat design and building,
    Outrigger Sailing Canoes https://outriggersailingcanoes.blogspot.com/?m=1
     
    Last edited: Jan 26, 2026
  14. WillyOcean
    Joined: Dec 2025
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    Location: Carnation

    WillyOcean Junior Member

    That's whats up. I feel like i have seen both hose videos before and definitely pulled inspiration and drive to not give up on my idea. If the task you build those for was having a good time I would say you accomplished the goal.

    Is the Hobie wave tender still in action?
     
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  15. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Senior Member

    The Hobie Wave is in desperate need of a new trampoline before I can sail it hard like I do during winter, so it’s still setup as a tender but I ended up swapping the Honda 8 for an EPropulsion ELite electric outboard that I can easily remove on the water and transfer over to my Trimaran for getting on and off my mooring and cruising up river.
     
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