Discussion in 'Boat Design' started by PsiPhi, Jun 12, 2009.

  1. PsiPhi
    Joined: May 2007
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    PsiPhi Newbie

    Looking around, trying to decide what I really want, and I find a variety of catboats that look appealing.

    I was looking at the Charles Wittholtz designs (15ft & 17ft) that would be about the size I would want.

    One thing is that they are all v-bottom and >12inch draft. There are places around here (that I would like to sail) where the water is only 8~10 inches.

    Are there any flat-bottom designs?

    Yes, I've seen some, all open boats, I was looking to have a small cabin for overnighting.
    Could you add a cabin to these without disrupting the design?

    I did look at Jim Michalak's FatCat2 - looks like a quick and simple design to build, just not sure how it would perform compared to something like the Wittholz ones.
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Are there any flat-bottom designs?

    Sure BUT , when sailing the chine may be beyond your draft limit , so you would have to sail very underpowered , and might not be able to go to windward in thin water, without dragging mud.

  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Catboat Book
    by John M. Leavens, Howard Irving. Chapelle
    Chapelle, Howard I. American Small Sailing Craft
    Shock, Edison Irwin. "How I Took Pinkletink's Lines." In The Catboat Book, ed. John M. Leavens, 38-41. Camden, Me.: International Marine Publishing Co. for the Catboat Association, 1973.
  4. sunsburydotcom
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    sunsburydotcom Junior Member

    I'm in the same boat

    I have been looking for about 2 months for the same thing. So I decided to come up with my owne. A combanation of a lot of difrent boats I have looked at. I have posted my design. look for flat bottom catamaran. Not sure how it will work but I will know by next summer. I going to build it this winter. I'm not to concerned with the sailing as I want a river drifter for a 112mile float trip for the summer. I do have a 30 ft mass I will be installing. LOL I have never been on a sail boat. But I did stay at a Holiday Inn. I wanted the wide flat bottom. I'm caculating it will draft about 6" to 8" loaded.
  5. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Yeah, a catboat will sail like any sailboat, most of the time heeled to some point somewhere between 5 and 15 degrees. When heeled, any shallow vee bottom (which is typical of most Cape Cod catboat hulls) will stiffen up a lot when the bottom becomes flat---- by lying at the angle of the deadrise.
    You can build a dead flat bottom boat for very shoal waters (Elver for example), but sailng under such conditions becomes limited to downwind only as leeway will be extreme.
    A flat bottom that's also very wide (catboats have extreme length to beam ratios---- sometimes up to 2:1) can stand up to a huge press of sail, but it will also need a lot of sail to go. The hull shape is extremely inefficient except at very low speeds.
    I have what was originally a catboat, converted to sloop. However, it has five feet of beam on fifteen feet of length. I can sail in 20" with full keel. Not bad---- it's not 6" but I have rarely touched bottom, and when I did, I shoved off easily.
    A Wittholz cat would be a heavy boat. It would be a lot easier to make a lighter boat with less draft. You could build a wholesome 16 footer with only 6" of draft even with a vee bottom--- half the weight. It could be narrower and still very stable. It would require a lot less sail area and a much lighter mast. Easier to shove off a shoal as well.
    Traditional Cape Cod cats have their place---- the area south off Cape Cod where a rugged yet shoal sailboat can carry a big payload across unmapped sand shoals that can rise overnight from wave action.
    For most sailing for pleasure, keep the simplicity of the rig, but narrow the beam down and lighten up the boat and you'll save a lot of money (a true 15-17 ft Wittholz or similar catboat is as much work to build as any other boat of 20-22 ft). I'd go for the longer (faster) boat any day.
  6. PsiPhi
    Joined: May 2007
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    Location: Queensland

    PsiPhi Newbie


    Thanks for a good and complete response, some things there I hadn't thought about.
    I had thought, like others, of creating my own custom design, or maybe taking an existing design like the Wittholz and making the deadrise shallower and adapting the construction for more modern methodologies. I'm just a bit reluctant to mess with a good designers work as am sure I would be more likely to degrade it rather improve it.

    The catboat appeals as my interest at the moment is in family cruising and you get a good amount of cockpit space in these.
    I'm not concerned much about speed or racing etc.

    I'd be interested in what you consider a "wholesome 16 footer".

  7. alan white
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    alan white Senior Member

    A wholesome 16 footer is going to be a good family boat with somewhat robust construction, a boat that is built for any nearshore conditions, one that will get you home in a blow. It will have comfortable accomodations, meaning good seating and a small storage locker or cuddy would be nice too.
    The hardware will be strong and the rigging on the heavy side of average.
    The Haven 12 1/2 is such a boat. Not a shoal boat however. A wittholz cat would definitely be considered wholesome. There are many many others. A wholesome boat is seldom built for a special purpose such as racing or to be easily trailered by a small car (though most 16 footers could be trailered by a small car). It is a dependable boat that does most everything well without any extremes.
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