fast but lightweight cruiser

Discussion in 'Multihulls' started by Gary Baigent, Dec 25, 2013.

  1. redreuben
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    redreuben redreuben

    Under the cockpit ? Sheesh, cramp a mans style why don't you !

    Move the mainsheet aft and put twin cockpits either side of aft cabin using the mainsheet track as rear perimeter ?
    In way of your cockpit aft cabin just needs some headroom i.e., a tunnel with sloped backs for seating in each cockpit ?
    Probably needs a bigger boat for that.
     
  2. Gary Baigent
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    Gary Baigent Senior Member

    Good suggestion, Red - but if the main traveller is moved aft, don't have enough width for the semi-circular track to operate properly, meaning I'll have to add a vang track further forward to keep the sail flat when broad reaching ... which will foul the twin cockpits.
    But I like the idea of twin cockpits. Will work on it just for you. Cheers.
     
  3. Gary Baigent
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    Gary Baigent Senior Member

    Has been done, RR, cockpit moved forward but made into one because why scramble over a high step in the middle for a double cockpit setup, and plenty of room aft for a double bunk now; also curved the deck to transom to make a continuous line.
    Somehow, don't know how, overall beam has moved to same as overall length, square, 10 x 10 metres.
    Find it difficult to control myself ... not a high performance boat ... but unintentionally moving closer in that direction. Sort of a Stranglove thing, couldn't stop the rigid salute.
     

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  4. redreuben
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    redreuben redreuben

    I'm liking it Gary ;)

    Carry on.
     
  5. redreuben
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    redreuben redreuben

    Besides, scrambling is a racing thing.
     
  6. Gary Baigent
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    Gary Baigent Senior Member

    True, but I like a low boom and the double cockpit thing would have meant trouble, like decapitation or flipped overboard during unintentional gybe, your back turned and talking BS while imbibing. Now, with single design, one could duck below and save oneself.
     
  7. redreuben
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    redreuben redreuben

    Now imbibing, that's a cruising term ! ( thinking goblet of Westmalle triple :D )

    I am understanding.
     
  8. redreuben
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    redreuben redreuben

    Just backing up a little here, you said
    "but if the main traveller is moved aft, don't have enough width for the semi-circular track to operate properly"

    I would take the track all the way round to the main beam, thats what I meant by twin cockpits either side hemmed in by the track.
    Inboard side of the cockpit is a seat with sloping back.
    Or make the root of the beam bigger for more bunkspace ala Horstman.
     
  9. Gary Baigent
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    Gary Baigent Senior Member

    I left the after track as it was because with the cockpit shifted from aft to directly forward of it, still allowed the wide track. So don't need a vang setup. Thanks for the suggestion RR, serendipitous result.
    To take the track all the way round to the main beam would mean extra structure to support the outer ends ... and you never run flat off anyway - so would be extra weight and superfluous. I'm a minimalist, didn'tchaknow.
     
  10. Doug Lord
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    Doug Lord Flight Ready

    Planing Amas?

    Gary, I've wanted to ask you about this for awhile but keep forgetting: are your small amas designed to plane? I can see nominally double ended in case of full immersion at slow speed but is the bottom designed to provide dynamic lift with intermittent contact at high speed?
     
  11. Gary Baigent
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    Gary Baigent Senior Member

    Oval bottoms to floats, Doug, they'll be tensioned thin ply (glassed later) so need the curve for stiffness. Haven't tried flat planer type bottoms but think they will be noisy. Could be wrong here, anyone else know? Also more wetted surface equals more stick in light airs, also requires more stifffening material, equals more weight. This is a cruiser ... but as light a one that can be sensibly built using basic materials. Also the foil will do most of the lifting work, not the float.
     
  12. philSweet
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    philSweet Senior Member

    Sorry for the delay, yes , it is a tri hull. I hadn't loaded any amas yet. Tri's aren't my thing. I have small hours in a few different cats. The usual suspects - most of the Hobie and Nacra inventory, Prindles, a Warram, a Piver, an Iroquois, and I helped deliver an Alliaura 50 to the Caribbean.

    I wanted to see how the big design ratios morph as you go from a skiff, to a skiff-with-training wheels, to a tri, to a cat. I wrote a spreadsheet a couple years ago that held weight, main hull length, RM (at 10 degrees heel), and wetted surface area constant and slowly morphed a parametric model from skiff to tri to cat. For this exercise, I constrained the ratio of KMt/KMl to see what happened to the amas. It took a while. When I was done, I went looking for comparables in the marketplace and was quite pleased to find a Corsair 32 that had pretty similar numbers. If the Corsair didn't fold for trailering, the numbers would have been even closer. I had a bit less beam, a bit less sail area, 200# lower weight estimate, and a wider main hull. I also set the amas a touch higher to get useful RM from the main hull (about 25% of RM at 10 degrees). The higher amas and heel angle might be an annoyance from a visibility standpoint though, when looking to windward.

    One thing I can't seem to do is get a small tri to go with a smallish sail area. On paper, they seem to want a larger minimum area than a mono or cat. I think adding a foil could simplify the ama construction a little bit and save a little weight. If a 32' tri was planned with a 20' beam and 30' amas that were around a foot beam, using a foil looks like it could allow you to shorten the amas by about five feet or so and have about the same feel to it. Building an ama with a 25 aspect ratio ought to be a bit easier than building one with a 30 L/B.
     
  13. redreuben
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    redreuben redreuben

  14. santacruz58
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    santacruz58 Senior Member

    new cruising boat

    Did you ever start this boat Gary? It looks interesting. Or did you decide to modify groucho marx into a more friendly cruising boat. I certainly has the length. Thou I am not sure how much space is inside in it present form.
    nelson
     

  15. Gary Baigent
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    Gary Baigent Senior Member

    No, neither changed Groucho (which has a very narrow main hull and therefore not suited to carrying extra accommodation and weight) nor continued on the double rigged cruiser ... but still thinking about it. Thanks for reminding me. Been sailing and making slight improvement changes to the vicious Sid instead.
     
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