Sail choices

Discussion in 'Multihulls' started by Kudzu, Oct 19, 2011.

  1. Kudzu
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    Kudzu Junior Member

    I pretty much have my design of my skin on frame tri finished. My next step is to settle on the sail plan. I really like the cat ketch rig and it is my first choice. Drawing it up I decided to get fairly detailed and ran into some thing I had not foreseen.

    [​IMG]

    I had to do a lot of moving stuff around to get the sails on the boat, the cockpit and the sheets. Still have one line pretty close to your head but I think a little more tweaking it could work.

    I really like the unstayed mast(s). Make set up much simpler and quicker. But I kept thinking about the main and jib and could see some advantages there too. Main one being being able to use the jib for tacking. I figured an inexperienced sailor could learn to backwind the jib pretty quickly.

    [​IMG]

    Now I am trying to decide on which one. They both have good and bad points. Both present problems to overcome with the construction of the frame.

    Just thought I would toss it out here and see what others thought.
     
  2. cavalier mk2
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    cavalier mk2 Senior Member

    Too much area forward on the catketch for me. The lee ama bow would depress too much going to windward. If you made your sloop rig a sliding gunter you could keep the same size jib and have spars that stowed in the length of the boat. Works great on my sailing canoe.
     
  3. Fanie
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    Fanie Fanie

  4. WillyG

    WillyG Previous Member

    The COE of the combined ketch rig is proportioned between the two rigs. It is not a function of how far forward the first rig is located any more than it is by the placement of the aftmost rig. Draw your vectors from the combined rig point and perhaps you'll see a different relationship.
     
  5. Kudzu
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    Kudzu Junior Member

    The CE of the cat ketch is about 2 foot in front of the mizzen mast or 8 foot behind the main mast. 5 foot above the foot of the sail (roughly 8 foot above the water).
    That places is behind the head of the figure in the boat. I haven't confirmed this but I am sure that is further back than the Bermuda rig is.
     
  6. TDSoren
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    TDSoren Junior Member

    Trimaran rig

    I put a cat junk on my little 10 foot seaclipper.

    http://smalltrimarans.com/blog/?p=6745

    Cambered panels for decent windward capability.

    reef from the cockpit, quickly and easily.

    lots of sail area for light air so i don't need to mess with Genoas or spinnakers.

    http://www.youtube.com/user/tdsoren1?feature=mhee

    This is a video of basically the first time out. I've since shortened the mast, stiffened the upper and lower yards and eased halyard tension to avoid those vertical wrinkles and improved the sheeting. Now I just need the time, wind and someone to hold the camera to show me how the tweaks work.

    Anyway, something to consider.

    Tom
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    When calculating the CE for a cat ketch like that (of those general proportions), use 65% - 70% of the mizzen area, which will move your current CE forward a bit.
     
  8. Petros
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    Petros Senior Member

    I would keep it simple, less messing around on set-up, less to go wrong/break, less work when under way. I like the sloop rig, looks simple and fast.

    the sloop rig is well proven, efficient and much less hardware. For simplicity and ease of handling there is not much that can beat a junk rig. I would stay with a single mast with either the sloop or junk. Consider that the all of the fastest sail boats ever built were all sloop rigged. There is a reason for it.
     
  9. Kudzu
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    Kudzu Junior Member

    I remember reading that somewhere and forgot about it when I calculated it. Thanks for reminding me. I quoted the wrong figures too, I was looking at another set of sails calculations. CE is actually going to be ahead of the sailor somewhat.

    That is exactly why I like the cat ketch. Free standing mast, less rigging and I dare say it is simpler then the sloop rig. Sails are self vanging, minimal hardware and you don't have to deal with a stayed mast. Unless I find a used mast the hardware costs are a lot more. One of the design goals is keeping the cost down as well as easy build.

    With the cat ketch tacking is just a mater of turning the helm. You don't have to do anything else. (assuming it will tack with no drama or course and that is a concern). At the end of the day, wrap the sail around the mast(s), pull it out and store them.

    Sloop would be faster I am sure, but ultimate speed is not one of the design goals. But that rig does have some advantages too. I have been back and forth on this a lot. I like the cat ketch slightly better but the problem is neither one really stands out above the other to me. I think I have made up my mind then I start thinking about some drawback and start to lean the other way. Glad I some time before I have to decide.
     
  10. Kudzu
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    Kudzu Junior Member

    Tom, I know nothing about a junk rig but it is interesting. Will have to look at a little.
     
  11. cavalier mk2
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    cavalier mk2 Senior Member

    I was looking into an old Brown 41 tri some years back and I called Jim Brown who sent me some plans. They were designed as a ketch then a cutter and what they found was that while the center of efforts lined up the downforce from the mainmast forward along with a individual COE more forward for the main mast made the boat need to reef sooner than the cutter as the bows dug in slowing it down. He never designed another one. A cat yawl keeps the sails out of the bows for the 2 masted approach or a catketch with the stick further back lets you hoist a wire luff jib/screacher for ghosting.
     
  12. redreuben
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    redreuben redreuben

    There was a successful trimaran on the east coast of Australian in the early 80's ? called Shanda that had a schooner rig, perhaps you could look at that format
     
  13. redreuben
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    redreuben redreuben

  14. redreuben
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    redreuben redreuben

    And a piccy :)
     

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  15. cavalier mk2
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    cavalier mk2 Senior Member

    Love it Redreuben. The Nicol ketch has the mast set slightly forward but shorter to keep the fore triangle CE in the same location. Both the yawl and ketch have a jib to the bow with the shorter mast but the sloop sets the forstay back 3+ feet to offset the taller fore triangle. These things really make a difference, when racers add length it is usually to the bow so they can drive harder. Some of those Spronk schooners are pretty fast in a breeze too but under rigged for the light stuff. Might be fun to put maststeps in different locations to make playing with rigs easy. I'd recommend tarp sails till everything is sorted out.
     
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