Skinny microcruiser thoughts?

Discussion in 'Boat Design' started by Cedric Oberman, Dec 4, 2023.

  1. Cedric Oberman
    Joined: Nov 2020
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    Location: uk

    Cedric Oberman Junior Member

    Hello All,

    I'm blessed with a small, convenient, warm-ish and, most importantly, cost free build space, and I'm toying with building a ply boat in it, but it has serious access limitations. A 76cm doorway and a tricky dog-leg, so anything coming out of there needs to be less than 76cm x 480cm.

    A multihull I hear you chorus. And of course you're right But I already built a badly executed Dierking style proa in there, which was fun, but wet and cold (I live in England fer crissakes!) , also there's so much duplication in such a build. Certainly a multihull is the only sane course. But, if only for the mental exercise; what about the insane course?

    I'm no expert, but I know many of you are, so perhaps you could tell me if I've got the gist of this:

    Looking at Matt Leydon's Elusion and Sven Yrvind's, Exlex boat/capsules, it seems that 100cm beam is the skinniest practical b.o.a. for a microcruiser. I assume that little cruisers want the form stability that beam gives, to avoid needing to put so much ballast on board to stand up to the sail, that it would make the boat dog slow if it indeed had the buoyancy to stay afloat. And I suppose that kind of craft doesn't really want to have a deep keel because you lose a lot of the practicality of a small boat if you can't land and launch from a beach. So, does this definitively mean that a hull 76cm wide is a non-starter for a sea-worthy micro cruiser, or can it be designed around? There would be no effective vertical limit, so it could have bags of freeboard and be a full, high prismatic hull with a deep vee at the bow and a bit of flair, but fairly slab sided amidships I would have thought. Maybe a long keel with internal lead ballast so it can still be beached and handle a bit of a sea without rolling around, but the c.o.g. would be comparatively low beneath the c.o.b. so it could take the sail it would need to shift it. I suppose it would look a bit like a fish for being strangely proportioned, or like one of John Welsford's tiny cruisers but viewed in a curved mirror. My hunch is, it isn't worth the compromises involved, but on the off-chance that you disagree, or better yet, you know of a set of plans that I've missed, for a comically slender one man cabin cruiser sailboat boat like a fearful hybrid halibut/nano-submarine, I just thought I'd ask.

    Season's greetings
     
  2. Milehog
    Joined: Aug 2006
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    Milehog Clever Quip

    Can you bring the boat through the door on its side?
     
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  3. Cedric Oberman
    Joined: Nov 2020
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    Location: uk

    Cedric Oberman Junior Member

    Yes, but it would need to be very flat like a punt as it has to go down a passage.
     
  4. Robert Biegler
    Joined: Jun 2017
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    Robert Biegler Senior Member

    You know that question is catnip, don't you? Expect some excited pouncing, and people taking you at your word. I certainly intend to, but I'll lead up to it gradually, starting with the most orthodox proposal.

    1) Build two halves with generous flanges down the centreline, glue them together once they are out of your workshop.

    2) Keep it narrow, have two canting keels, either hinged at the bilge like the Defline 19, or hinged at the deck, with a little recess in the side of the hull so that the side is smooth when a keel is not canted. Leave the leeward keel down, cant the windward keel as necessary. Cant both for shallow draft when beaching the boat.
    [​IMG]

    3) Build an amaran or triscaph:


    4) Keep it narrow, and stabilise it with a hinged Bruce foil:
    [​IMG]
    More information at Hinged Bruce foiler - Amateur Yacht Research Society https://www.ayrs.org/phpbb/viewtopic.php?f=19&p=4429#p4429 That will need a much better foil than the one I built. However, I want to save some weight and put the foil on a string, leading me to

    5) Join me on the dark side, keep your boat upright with a foil on a string, like so:

    That is a boat that only sails on one tack, and trying to retrieve one paravane and deploy the other in a tack or gybe is a bit of a bother (meaning I tried and failed), and having a reversible paravane but tack the boat would mean you couldn't gybe

    so make the boat a proa. A short, monohull proa, but still a proa (I plan to use a folding canoe I've got lying around). Roughly like this, only not with that deep V hull that prevented me from steering the boat by shifting the paravane:
    [​IMG]
    On the AYRS site, Theo Schmidt announced a while ago that Roger Glencross has a few paravanes of the type shown below that he can no longer use due to age. If they haven't been taken yet, you could get them for free:Hapas free to a good home - Amateur Yacht Research Society https://www.ayrs.org/phpbb/viewtopic.php?f=34&p=4425#p4425 I am too far away to pick them up. Anyway, you would shunt, like this guy, only with a hull:


    6) Who needs a hull when you can fly (see above).
     
  5. gonzo
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    gonzo Senior Member

    What is the maximum length possible?
     
  6. Cedric Oberman
    Joined: Nov 2020
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    Cedric Oberman Junior Member

    Thanks Robert, Excellent ideas all. That tripod type boat is outrageous! Like something you'd toy with as an idea and dismiss as impractical. But it works pretty well eh? Hmm. much thinking to do.
     
  7. Cedric Oberman
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    Cedric Oberman Junior Member

    16ft
     
  8. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    One would be Whissocks Design I think 077 at 15'7" , would be designed for your area
     
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  9. Milehog
    Joined: Aug 2006
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    Milehog Clever Quip

    How permanent are the passage walls? Are they both structural?
     
  10. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Just as you could build your cruiser in two halves, You could also build a topside and a bottom half separately, take them out, as has already been suggested, sideways, and assemble the parts directly on the trailer. Set the bolt on keel under the bottom, fit the deck and cabin on top, after fitting the interior out. Pretty much how many production boats are assembled.

    This could give you a hull that is 16' loa x 6'4". Lots of form stability, especially if you design her flat bottomed, like a sharpie.

    -Will
     
    Last edited: Dec 5, 2023
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  11. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    My 16ft sailing canoe had more beam than that, and a cockpit that could be slept in. See: Chautauqua (gentrycustomboats.com) which you could take out on its edge, being thinner keel to deck than it is beam. Quicker and cheaper to build than a plywood boat, unless you go simpleton like a Bolger June Bug, with the option of a canvas or lightweight deck to keep water out. The hull is well proven, so that is where i would start, its as much "box" for the material as you are going to get; modify everything else to your needs.

    [​IMG]
     

  12. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    upload_2023-12-5_12-15-17.png

    Bolger Otter. I was looking to build a CLC nesting dinghy

    [​IMG]

    but it was too deep to get in the back of my car, so i built the sail canoe instead.....which got a lot of use just because it was so easy.
     
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