6.5 to 7.5 metre performance/cruise multihulls

Discussion in 'Multihulls' started by Gary Baigent, Feb 27, 2015.

  1. Gary Baigent
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    Gary Baigent Senior Member

    Here you go. These views show the after end of the beam and trailing edge of the floats and foils - remember the beam angles forward. So in the images the beam is rotated clockwise to fit into the female box of main hull.
    There's not enough room in our section between shed and neighbour's fence to set the Frog up with beam across the hull. Well, there is if I take everything apart and juggle the main hull around between trees and shed to lay across the section. The floats (if you can call them that) and foils make overall beam 7.4 metres - which is a little extreme for a 6.5 metre boat?
     

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  2. sigurd
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    sigurd Pompuous Pangolin

    Sweet! I really don't know if it's extreme, it is irritating to have to reef because you can't keep the bows up in a cat - just because it had to be 16' and not 18' or more, for some odd reason. It's not that a wide beam increases the chance of pitchpole, but that the beam is the 'size' of the boat - in the sense that it drives the RM and thus most scantlings - and that the length is almost free (in weight and money) by comparison.
    In froggy it is easy to see why it is over square, and in fact, my proa as drawn ended up with the beam to length almost exactly half of yours which is a perfect match since you are using only half of it at a time.
    How far forward do the foils end up?
    One thing to look out for with the long beam is the torsional stiffness - if the foils are allowed to change AoA willy and nilly, odd things can happen. It does look pretty stiff.
    The long beam will delay the vaka lifting out of the water until a higher (heeling moment and thus most likely) speed - maybe not a bad thing, considering the foils are not very long and the hull looks fast.
     
  3. Gary Baigent
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    Gary Baigent Senior Member

    The beam on main hull is at the halfway mark, 3.25m and then rakes forward so the foils are positioned maybe 250mm or so forward of central position - have forgotten the exact figure, will measure tomorrow. This may be a mistake (compared to the 50/50 position on the new cat foilers) but it's what I've done in the past (see photograph of over square Misguided Angel) and I like the security of not burying the main hull bow from tripping. Old fashioned, set in his ways bloke that I am.
    However I've got some semi-radical ideas for the rig; will talk to Auckland sail making experts and post drawings later.
    And this boat started as a very simple and basic design suited for the masses ... and now look what is happening.
     

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  4. Gary Baigent
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    Gary Baigent Senior Member

    La grenouille.
     

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  5. Gary Baigent
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    Gary Baigent Senior Member

    Found a shot of 20 year old Groucho and couple of years old Sid moored at Cox's; interesting comparison? Another shot of Frog - ready to be shifted out. Now working on mast base and frames.
     

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    Last edited: Jul 20, 2016
  6. Lami
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    Lami Junior Member

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  7. Gary Baigent
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    Gary Baigent Senior Member

    Very interesting. Neat looking cat. The double rig also. I tried a similar double rig setup on Misguided Angel but had trouble with leech falloff. Should have persevered but weakly threw in the towel and changed back to sloop. My 18 foot Cox's Bay Skimmer monohull also had two rigs (but fore and aft) and ended up with a very large area of sail for the boat's size. Had to reef fore main in any decent wind - and especially so when sailing solo.
     

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  8. Gary Baigent
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    Gary Baigent Senior Member

    Sailmaker Bill Barry has foolishly become interested with the double luff wing rig I'm thinking about for Frog - and here's his sketch, which cleverly rids the problem of retaining taut sail surfaces for both windward and leeward sides of the wing sail. The two of us are following our noses at this stage but it is good to collaborate with another slightly crazy Kiwi. We both have differing, but very similar ideas. Bill wanted to build a prototype rig for a 4 metre boat he has in mind but I'm too impatient and when I finish building the leading edge D shaped cross section mast in the shed, want to go straight to building Frog's deck sweeping rig.
    Meanwhile I've put Groucho up on blocks at Cox's and finally got around to repairing the smashed port float junction to beam - when the mast came down in earlier savage winds. The buckled float has been flopping around, crudely lashed up with ropes while on the mooring and concerned locals contacted me with warnings. You can see what is left of the wing mast on top of the beam. Weather has been insane here, continual high winds and rain, and yet more to come.
     

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  9. redreuben
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    redreuben redreuben

    Double sail

    Gary my idea on this was to connect the two clews with a loop with a pulley in the loop connected to the out haul so the sails can move through the pulley on each tack ?
     
  10. Gary Baigent
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    Gary Baigent Senior Member

    Yes, very much my thoughts except I was thinking of a peg through slots in the clews, simple stuff. Bill's cam would probably create a cleaner double sail shape though. I have to do some more contemplated research while lying in the bath.
     
  11. redreuben
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    redreuben redreuben

  12. Gary Baigent
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    Gary Baigent Senior Member

    Thanks Red. And here's another interesting design.
     

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  13. Doug Halsey
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    Doug Halsey Senior Member

    Is that an A-Cat? Do you have a link with more info?
     
  14. Gary Baigent
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    Gary Baigent Senior Member

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  15. waynemarlow
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    waynemarlow Senior Member

    Wasn't there some discussion on a D shaped mast with bolt rope on each side of the D, the 2 sided sail just goes up the bolt ropes and the angle of the mast dictates how much camber there is on each side.
     
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