Big MAC Cat or Tri?

Discussion in 'Multihulls' started by RHough, Apr 21, 2006.

  1. RHough
    Joined: Nov 2005
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    RHough Retro Dude

    All the talk about making multi-hulls from one or more mono-hulls has gotten me thinking ... (dangerous I know) :)

    How about using boats that no one likes?

    Two possibilities spring to mind. Using two MAC65's to make a 65ft cruising cat. Keep both rigs and lose the keels. Add daggerboards in each hull instead. The connecting structure could be pretty massive and still be lighter than the two keels. No need to build a centre cockpit or accomodation, just beams and a cat walk so you could walk to the windward steering station.

    The other idea would be to take a MAC65 and two MAC26's and build a trimaran. One of the knocks on the 65 is small living space for a 65 footer. The 26 has lots of space for a 26 footer. The owners stateroom would be in the main hull, and the two amas would be guest cabins. I figure that the L/B ratio of the 26's wouldn't be a problem as I would expect them to plane (as designed). For long periods of trade wind sailing, the windward hull would carry water ballast to increase the RM. With a little bit of planning the boat could have three steering stations ... one in each hull ...

    I'm leaning toward the big cat idea over the tri with planing amas because the biplane rig (I love biplanes) of the cat would give it a huge SA/D advantage in light air. Having a 150HP engine in each hull should double the under power cruising speed and range too.

    If I can't find two matching 65's to build the cat from and have to go with the trimaran concept, how much bigger would the rig have to be to get good performance? To keep the mast height down, would a cat ketch rig or schooner be a good choice?
  2. frosh
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    frosh Senior Member

    Hi Retro Dude, You said this was dangerous and I definitely agree; I'm sure that you have read the recent postings in this type of scheme.
    However the biplane rig idea is really good for cruising and I will direct you to web site you may not be aware of looking at a much smaller new cat with biplane rig by Schionning, a well respected multihull designer.
    Make sure you also click on the two links at the bottom left of the opening page. Radical Bay sailing, and Radical Bay article 2
    Have a chat to a naval architect, and I wouldn't be surprised if he was to start running as fast as possible!
  3. RHough
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    RHough Retro Dude

    I should have fleshed out the ideas a bit more and saved the post for next April 1st. :D

    It seems obvious to me that any kluged together multi-hull will be a worse boat than a boat designed for the purpose. On the other hand, a long shinny hull like the Mac 65 is closer to the proportions of a catamaran ama than most mono-hulls. From a practical engineering standpoint for the idea to work, the total displacement of the new "boat" would have to equal the combined displacement of the two monos if you want the hulls to end up on their lines. Some of the weight of the keels would go to the bridge deck structure and the rest could go to extra tankage and a big genset. With the biplane rig, the bridge deck could be a huge sunbathing platform during the day and with the big genset you could have a live band and dancing at night. :)

    There is no way that I'm even remotely serious about this, the flight of fancy was prompted by the other threads and the thought that a Mac 65 looks a lot like half a catamaran. :)
  4. Tad
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    Tad Boat Designer


    It's all been done before, sorry :D

    I attach a drawing of two Mac 65's made into a cat. This was done by Vince Bartolone at least 15 years ago when hulls were available from the Mac factory. Vince was the great artist/stylist behind the sucess of the CSK (Choy, Seaman, Kumalae) design office.

  5. RHough
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    RHough Retro Dude

    LMAO! The idea was not so far off after all! Too funny! :)

  6. marshmat
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    marshmat Senior Member

    Wow... what living space on such a thing! The perfect anchor queen indeed! (Since I certainly wouldn't trust a single 65 in real waters, let alone two;) )
    Having said that.. I like tris. I actually have a few sketches floating around of big motor tris where the amas are used as very private guest staterooms. What would be needed to hold two mac26s to a 65.... hmm.... again, an anchor queen since the marina fees will be horrendous as would the seaworthiness, but it's an entertaining thought.
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