Voyaging Micro Yaschts

Discussion in 'Sailboats' started by sharpii2, May 13, 2013.

  1. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    Hi, everybody.

    I recently finished reading Serge Testa’s book “500 DAYS” about his circumnavigation in a 12ft boat, which he designed and built himself. (see attachments below)

    I thought it might be interesting to discuss the idea of micro voyaging boats and the problems and challenges of designing a successful one.

    My proposed FOOTBALL concept was drawn before I read the book and saw the specs on Serge’s boat, ACROHC AUSTRAILIS. The comparison may be interesting or at least entertaining.

    FOOTBALL was conceived to break Serge’s record of the smallest (shortest) boat to circumnavigate the planet. It’s 10ft ( 3.05m) length is the shortest length I would consider, if I were going, myself. This accounts for my 6ft minus height and allows barely 2ft on either end.

    Now that Sven Yrvin is already building a 10ft boat for the same purpose, my fantasy of a record attempt is pretty much doomed.

    However, a 10ft voyaging boat is at least interesting, if not all together practical (it may have virtues of its own).

    ACROHC was designed with Weatherly performance as a priority. Its deep ballast (see attachments), tall mast head rig, and large Genoa jib, compared to a small main, all clearly point out its designer’s intentions. According to his book, ACROHC turned out to be quite Weatherly.

    FOOTBALL is conceived to have mediocre, but adequate windward performance, with moderate draft and down wind directional stability being the priority. The tiny jib is intended only for down wind sailing (it’s supposed to produce a substantial lee helm when set). I also went for a pram like hull form, so I could have more balanced ends for the same reason. ACROHC had a wind vane. FOOTBALL will not have one.

    Although Serge went for a tall rig, he made sure it was quite strong. Notice that he went with double spreaders when he might have been able to get away with just a single set. Indeed ACROHC was never dismasted, even when sailing through tropical cyclones.

    With FOOTBALL, I have a similar philosophy. Instead of a tall rig with spreaders, I went with a much shorter mast (measured from the deck), and a gaff rig with three over sized stays.

    ACROHC was quite stiff, with here deep ballast. Indeed, ACROHC was never capsized, though she ran aground at least four times during the voyage.

    FOOTBALL will be much more tender, though she should still have absolute stability. She will be easier to knock down than ACROHC, though I’m not sure she will be any easier to capsize, but I wouldn’t be surprised if she was.

    Below, I have the specs I have been able to noodle out of Serge’s book, compared with those of my proposed design.

    ACROHC AUSTRAILIS------------------------------FOOTBALL
    Designed by---------------------------------------Proposed by
    Serge Testa---------------------------------------Sharpii2

    Length = 11ft 10 in (3.61m)------------------------Length = 10ft (3.05m)
    Beam = 4ft 11in (1.5m)-----------------------------Beam = 4ft 6in (1.37m)
    Draft = 4ft 11in (1.5m)-----------------------------Draft = 2ft 9in (0.84m)
    Displ. = 1530 lbs (695kg) ---------------------------Displ. = 1700lbs (773kg)
    (likely, based on descriptions in book---------(Based on preliminary estimates,
    and some estimates, fully loaded)------------fully loaded)
    Sail Area = 111sf (10.3sm)--------------------------Sail Area = 107sf -----------------------------------------------------(9.95sm)
    D/L = 392 (avg. displ. of 1170lbs (532kg))------------D/L = 612
    -------------------------------------------(avg. displ. of 1350lbs (614kg))
    S/D = 16 (avg. displ.)-------------------------------S/D = 13.9 (avg. displ.)
     

    Attached Files:

  2. MikeJohns
    Joined: Aug 2004
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    MikeJohns Senior Member

    Here's a few pics I took of the boat Serge used. Note the pitch damping plate on the bottom of the rudder and the effective roll damping keel. I have them in high res somewhere if anyone wants them.

    http://www.boatdesign.net/forums/boat-design/acrohc-12ft-boat-around-world-12443.html#post95558

    You want a 'very' seaworthy design in an ocean crossing small monohull. And you will lose your rig if you get rolled. I think I'd be opting for very heavy displacement a large wetted surface area and a deep keel. ie a powerful little ship with good weight tolerance. Interview with serge worth listening to here: http://furledsails.com/article.php3?article=759
     
  3. Skyak
    Joined: Jul 2012
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    Location: United States

    Skyak Senior Member

    I have mixed feelings about these records that directly defy reason and safety like the youngest, shortest... I think they give mainstream media just what they want at the expense of sailing's image. On the other hand I love to see what is kept when the cost to carry is so high.

    I don't understand what is accomplished with the long keel with the hole in it. I would prefer a deeper higher aspect keel with a plate at the bottom. For damping I always wonder why a flywheel is not used to generate power from pitch and roll.

    The bow sprit is not counted toward length? If not, I would have a big beautiful articulating bow spit, given that this is basically a downwind run.

    My preference would be to have a competition with specific limits -who can go around the world in a 12ft boat better? Faster, Safer, more comfortably...
    And how about the record for the lightest boat to circumnavigate? Another great aspect of this type of boat is the low cost of the campaign. Maybe we could do a class for great lakes circumnavigation.
     
  4. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    Thanks for the pictures, Mike.

    Generally, I'd agree with you.

    In most circumstances, getting rolled does come at the cost of losing the rig.

    But there are notable exceptions.

    Sven Yrvin's original BRIS was rolled so many times, while sailing in the southern high latitudes, that he started designing later boats with the presumption that they'd get rolled as well.

    BRIS never lost her rig, though the main sail did get torn in one of her capsizes.

    I think there is a delicate balancing act between making a boat that can stand up to the wind and sea, and one that can roll with the punches.

    My personal preference, based on my readings, is a boat with a small working sail area and a and a very sturdy rig that can stand terrific punishment.

    Such a rig can drag along a limited amount of whetted area at a reasonable speed, in reasonable winds, so any cutting at the top has to be matched, to some extent, with cutting from the bottom.
     
    Last edited: May 18, 2013

  5. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    I would agree that half past ridiculous is within easy reach. As I stated in my original post, 10ft is the shortest I'd go.

    What is interesting about these boats is how effectively they can mangle common perceptions on what makes a 'seaworthy' boat. They also tend to demonstrate that it is much easier (cheaper) to push an unreasonably large load at a reasonable speed, than it is to push a reasonably small one at an unreasonable speed.

    I wouldn't favor a contest for the lightest boat, for this reason, as that would become an expensive, high tech extravaganza, with all kinds of expensive gizmos, such as solar powered water makers, egg shell carbon fiber hulls, and MRE's. Such boats would almost certainly end up being double outriggers, or even single ones, which wouldn't necessarily be all that short (a fast passage needs less stores than a slow one). I can see how such a contest could become very expen$ive. Shooting from my hip, I guess such a boat and provisions could come in at 500 lbs or less.
     
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