Why don't lots more people sail multis..???

Discussion in 'Multihulls' started by buzzman, Aug 14, 2013.

  1. oldsailor7
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    oldsailor7 Senior Member

    Bregalad.
    Sorry I duplicated your post. :eek:

    Yes the Nugget mast was built exactly as Piver specified it.
    10ft pieces of 2" x 6" Douglas Fir (Oregon) were chamfered and epoxied together, to stiffen the mast --but also reduce the cost of one very long piece of straight grained Fir. (If you could find one without knots). The resultant plank was then shaped to a symetrical streamlined section, in effect a wing mast. Mounting it on a trailer ball allowed it to pivot, but the degree of rotation had to be limited by stops ---because the very thin mast was held in line by three sets of cross trees and diamond wire braces. This ensured the mast could handle the loads in compression with little or no bending loads.
    The rear side of the mast had a narrow flat on it on which a sail track was screwed. This proved to be very efficient as the rotation of the mast ensured that the cross trees didn't interfere with the mainsail when sheeted out.
     
  2. El_Guero

    El_Guero Previous Member

    OK, now it makes sense.

    Gary is not camera shy.

    wayne
     
  3. Gary Baigent
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    Gary Baigent Senior Member

    wayne, that's not me in the photographs of the altered Piver Nugget, but me sailing mate Jacques de Reuck; who owned the boat, now sold to a kayaker around the corner in the Firth of Thames.
     
  4. El_Guero

    El_Guero Previous Member

    HAHAHA. I had no idea it was that close to someone I knew.

    Great.

    What if we built a smaller 'mast,' or 'boom,' to help with righting a catamaran?

    That with a little help from the ball on top of the mast, should be enough extra help, wouldn't it?
     
  5. MikeJohns
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    MikeJohns Senior Member

    But also a fact that a holed catamaran can sink to the bottom while a knocked down monohull won’t even be damaged !

    Without adding qualifiers to both those statements they are just diatribe.

    What's concerning is that this type of hype is used too often in multihull marketing and it bears no resemblance to any SOLAS assessment of a vessel. Since this website is here to discuss boat design we should keep it sensible.

    In my locale : There’s a large, very expensive, relatively new Cat on the bottom off Maria Island, it sank during a passage from Hobart after being holed at night. They reporting several repeated but ‘soft’ impacts. It was either a heavy semi submerged object that they ran onto or more likely a whale tried cleaning off it’s barnacles, Either way it sank quickly from one hull being breached and they were rescued from their life raft the following morning by another yacht. I know of many other catamarans that have sunk through my work with insurance companies, and have even been involved in the salvage of some of them.

    So why does it keep getting regurgitated, like your “Fact” above and in Cutonce's post? There is a dangerous fantasy that inverted Catamarans are safe platforms and to reinforce how safe they are they are compared with 'sunken' monohulls :rolleyes:

    What is actually being compared is Intact stability vs damaged stability and you need to understand why that’s not valid. To compare two craft you need to define them first, that includes it’s level of watertight subdivision and or positive floatation. You can’t cherry pick and remain objective. . If you want to damage one of the craft for the comparison you are simply deluding yourself and others.

    I didn't want to derail this thread, whatever leads to more people sailing any type of craft is a bonus. But lets keep the observations objective.
     
  6. MikeJohns
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    MikeJohns Senior Member

    Trimarans apparently make considerably better inverted survival platforms than Catamarans. The main hull inverted water level is lower, dry provisions, dry access to tools etc. These should be in a watertight accessible compartment on a Cat for better survivability as should shelter.
    Also cutting a hole in an inverted non-positive floatation Cat hull floating from trapped air would sink it.
     
  7. peterAustralia
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    peterAustralia Senior Member

    changing tack

    frank smoot and his diy-tris, has come up with a similar idea to me
    (please note that I am not saying that he copied it.. probably not as he is very smart,,,,, and even he did I dont care)

    what am I talking about? Franks new 24ft trimaran has dual external boards
    http://www.diy-tris.com/2012/images-2012/10-24-footer/30.JPG
    http://www.diy-tris.com/2012/10-24-footer.htm

    and here is something i drew up a couple of years ago
    http://www.tacking-outrigger.com/19_tri.html

    tube within a tube setup for boards,,
    not as fast as a true centerboard, but it opens up the interior. If Frank by chance copied my ideas (and i am not saying he did... as i said he is very smart).. gives me a boost in that thinking ideas that I come up with may work in the real world. Frank has come up with a real boat, not a pissy little image, so all credit to him

    n peter evans
     
  8. buzzman
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    buzzman Senior Member

    MJ
    Yeah, okay, I get your point. Don't compare apples with oranges. :)

    And I do agree with you over the point of cats VS tris for capsized floatation - why I'm building a tri and not a cat....

    And the point about cutting a hole in an inverted cat that doesn't have positive buoyancy is equally valid.

    Cats need to have much better water tight compartmentation, but as even these can be breached, positive floatation is preferable.

    Alas, this compromises build cost and internal accommodation so is seldom added to cat designs...or tris for that matter....or even monos.

    And as the Sydney to Hobart has proved on a number of occasions, racing boats losing their lead ballasted keel can also remain afloat.
     
  9. buzzman
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    buzzman Senior Member

    peter

    As far as I can tell, Dr Frank's 24-footer's leeboard mechanism is a single tube rotating inside the 'bearings' that pierce the hull - the grey bits.

    He's used two sections of uPVC pipe, joined at the centreline where the universal clamps are.

    So it's not strictly speaking a 'tube within a tube'.

    Apart from the sliding akas, your 19-footer is a lot like Ray Kendrick's Scarab 18, which could easily be lengthened to 19-ft by 'cribbing' the temporary frames a couple of inches each.

    What I like most about Frank's boat is the ease of construction. So simple. But that foam carving takes some practice, and he's obviously had a lot!

    It's interesting to look at the design solutions in it though - he wants a long narrow hull to get the LWL for max speed with low effort, and the extra space for two crew.

    Placement of the crew positions dictated by the leeboard compartment in the centre requires a two-mast rig, or a single forward cat rig, as the crew is sitting where a bermudan mast would need to sit.

    The first domino to fall determines what follows.

    For example, had Frank desired side by side seating, and the ability to hike out, he could have placed a cockpit at gunnel level to the rear, in much the same way that Richard Woods' Strike 18 is built.....seat of cockpit at 90deg to hull sheer, then a vertical backboard at the outer edge.

    Having both crew aft would have enabled a bermudan rig and, dare I say it, much improved performance.

    The small floats don't have enough volume to provide serious resistance to heeling, further limiting potential performance.

    But as Frank is not focused on performance, he designed it the way he did.

    But that same hull, with a set of 18-ft beach cat floats - say from a Hobie 18 or a Tornado, with appropriately stiffer beams and rig, could be some performer.

    One thing I like about his actual design is that it is a great boat for less able sailors. He has used foot pedals for the rudder and a hand lever for the lee boards, but it would of course be equally possible to produce a lever for the rudder as well, making this a great design for the disabled sailor.

    In that case, the small amas and low effort rig would make for much safer sailing for such sailors. Maybe a bit big....a 16ft version would be better, probably.
     
  10. El_Guero

    El_Guero Previous Member

    Making a capsized cat more floatable is easy.

    Real bulkheads. And 20% of the hulls filled with water resistant foam. Costs more, but will always float, even if it is as flotsam.
     
  11. buzzman
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    buzzman Senior Member

    E_G
    Sure, but the former detracts form the "open plan" *look* so popular these days, and the latter adds to the build cost.

    The only way that could ever be commercially viable is if it was regulated internationally, thus providing a level playing field for boat builders...other wise some charlie will always build a 'cheaper' boat by eliminating 'non-essential' items....suhc as floatation foam.

    Non-essential to the builder, that is..... :)
     
  12. El_Guero

    El_Guero Previous Member

    Now back to cats, I do not see why catamarans like Richard Woods Wizard & Sango (22' and 25') are not in the contention. http://www.sailingcatamarans.com/sango.htm

    I think a 30 to 33 foot should not be much more problematic either.

    Think of an f-boat, but instead of the center hull designed to float in the water, design it to float above the water ....

    Get out of the box (mono) and let's solve the problem.

    :)

    wayne
     
  13. El_Guero

    El_Guero Previous Member

    Yes, there would be resistance, but we could overcome that. Easily. Still build the 'open' look with 3.5" of foam sandwiched between .25" of ply for the cubby.

    Instead of international regulations, build a 'racing class.' That would encourage people to enjoy a specific set of plans approved for the class, but that can also fill the 'boat' as cruisers.
     
  14. buzzman
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    buzzman Senior Member

    The problem again is accessibility - in order to get enough beam to provide adequate performance for their LWL they are not trailerable without significant dissassembly.

    Therefore require mooring out....

    But otherwise an interesting design.

    Personally, I don't like the "centre pod" style cat which, as you point out, removes the drag of that pesky extra hull.....the pod doesn't provide full headroom whereas the pesky third hull does.

    Although the smaller racing cat style with the raised coachroof provides some full height space in many, the fact that the readily accessible space is only sitting headroom makes this less attractive than a simple monohull trailer sailer, which has all that minus the extra cost of the other hull.

    Sure, a centre-pod-style cat 'can' be fast - a mate's son sails one regularly in Pittwater - and they do provide that extra space over the straight two-hull-with-companionway style boats....but I'm not convinced it is anything more than a cost-cutting compromise.

    A racing cat for Him, with a day cabin for Her.

    If that's what your specific requirement is, go for it.

    If I was building a 24-fter I'd go for Bucc 24, or similar trimaran.
     

  15. El_Guero

    El_Guero Previous Member

    Not quite what I would want.

    I actually want an almost proa/cat. non-symetrical hulls. Giving the larger hull significant living space, not unlike a mono. And the smaller hull giving significant support/buoyancy. I am not sure it will work .... yet.

    And maybe make it trailerable, on two trailers ....

    ;)
     
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