Multi-masted sailing cats

Discussion in 'Multihulls' started by marshmat, Jan 3, 2009.

  1. marshmat
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    marshmat Senior Member

    In browsing through the brokerage listings in the back of the sailing magazines, I noticed something rather odd about the rigs found on cruising cats. While cruising monos seem to include a mix of sloops, cutters, ketches and the occasional yawl or schooner, virtually all cruising cats share essentially the same tall, high-aspect sloop rig.

    For a Hobie, a tall sloop rig makes sense. But on a cruiser? The sheet loads must be enormous, and of course there's the risk of a crash gybe when carrying a huge main on a long boom.

    So, why don't we see more multi-masted sailing cats? Other than the occasional Wharram soft wingsail schooner, they just don't seem to be out there. I would think that with two or three masts, each no taller than the waterline length of the boat, you'd have a greater choice of sail combinations, and they'd be easier to handle.

    I was doing some sketches last week on this idea, and figured that if you can keep the mainsails small enough (and the booms short enough), and use a spreaderless rig, it should be possible to set the mains forward of the masts on a sufficiently beamy two- or three-masted cat- thus generating lift downwind, and eliminating the evil crash gybe- without getting hung up on the standing rigging. You can do this with freestanding rigs, but to be able to do this cheaply with a conventional stayed rig- no carbon- would be an interesting possibility.

    So, do any cat sailors with schooner/ketch experience know why we never seem to see these rigs on multis? (Please don't say it's the racing influence.... I would like to think, however naively, that we can think about what might work on a cruiser without considering how it would affect the race ratings.)
     
  2. basildog
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    basildog basildog

    Matt,
    Not sure about the practicalities of multi masted cats, due to load bearing structures required. I did see a Jim Young designed schooner rigged trimaran around 45 feet a few years ago in NZ. It looked a very impressive machine.
     
  3. robherc
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    robherc Designer/Hobbyist

    well, I don't have any experience with this subject yet, but I AM working on a schooner/ketch hybrid-rigged trimaran design. If you're not in a hurry, give me a year or two & I'll prob. have developed some useful info through good-ole trial, testing, and (probably) swimming...rofl
     
  4. Eric Sponberg
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    Eric Sponberg Senior Member

    Marshmat,

    You are right in that multi-masted multihulls are rare, but not unheard of. Both Dick Newick and Chris White have designed and built such boats.

    In general, multihulls are a lot faster than monohulls, of course, and so can get by with just a single rig. This is because the speeds are such that most of the time, the apparent wind is forward of the beam. One rig is sufficient.

    The other reason is that sailors in general are cheapskates--that is, they watch every penny of cost and do not want to spend any more than necessary. Just go into any boatyard in Florida and ask if they would rather have powerboat customers (who spend a lot of money) or sailboat customers (who complain about every dollar spent). Multihull sailors are both cheapskates and weight fanatics. I do not mean this in a derogatory way, but to graphically make a point. Two masts are both more costly and heavier than a single mast, so if a single mast will do, that is what they will pay for. As a result, this is reflected in the market.

    However, the points you make about splitting up the rig and beign eaiser to sail on all points are valid. Because of the speeds involved, up to two masts is acceptable, but it would border on problematic to go with three, if only for the accumulating downwash effect of each mast on the other behind. The third mast would not generate that much useable lift.

    Another thing that is a constant source of discussion is what load do you design a multihull free-standing mast to? In an ideal world, you would treat a multihull the same as a monohull and design the mast to the maximum righting moment of the boat. But multihulls have huge righting moments, so such masts would be very heavy and expensive (see anathema to weight and cost above). Therefore, the recent trend is to design multihull free-standing (and stayed) masts to about 1/3rd to 1/2 of the max righting moment, and just be darned careful not to overload the mast. I personally think the jury is still out on whether that is a prudent idea, and I suppose time will tell.

    Eric
     
  5. marshmat
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    marshmat Senior Member

    For some reason I'm reminded of the "venitian blind" multi-wing aircraft tried by a few folks at the turn of the last century.... the ones that, if you managed to get them moving fast enough to generate any lift, would break up!

    Eric's point here raises another question though- the downwash problem is well known, but can it be minimized? I'm thinking either rotating mast (in the manner of a racing beach cat) or faired luff pocket (a la Wharram). It might be interesting to see how much of the apparent loss of efficiency of the downwind sail is due to turbulence spilling off the next mast upwind from it, and whether or not streamlining that flow would make any difference. The aviation world went to monoplane wings long ago for fast aircraft, but you still see a lot of biplane types where low speed capability is important....

    While a trained multi sailor might be able to handle a rig designed like this, it sounds like a hazardous idea if the skipper is coming from monos. A cat generates its highest righting moment when it just begins to fly the windward hull. To a mono sailor, used to judging rigging loads by angle of heel, that might be the first sign that it's time to back off- and you wouldn't want that to be at twice the design load of the rig.

    I have seen a lot of Hobies, etc. towed back to the beach after breaking something in the rig.... they don't seem to be very forgiving boats. A Hobie can be swum home, a 40' cruiser is a little harder to push around.
     
  6. yipster
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    yipster designer

    multi mast considerations for a cat are merely the same as for a mono
    on cats bi masts are seen more than lateral and do have my interest
     
  7. Tad
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    Tad Boat Designer

    Then there's the extremely rare Lug rigged 4 masted cat....

    4mastedcat.JPG
     
  8. sandy daugherty
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    sandy daugherty Senior Member

    The lack of multimast multihulls is easy to explain. Go fast people want the greater aerodynamic efficiency of a single mast, and go easy people want the simplicity of a sloop. In earlier times, Solaris sold a 41' ketch, simply to meet a perceived demand, but didn't sell many. Before self-tailing multispeed winches, there was an arguement for smaller individual sails being easier for an older cruising couple to handle. Today there are electric halyard and sheet winches, on 70'masts!

    So the answer is nearly always the same: demand determines what is built to be sold.

    The answer to the question you didn't ask is "Yes, a crew used to a ketch or schooner rigged monohull could sail a ketch or schooner rigged multihull, perhaps as well as a sloop-rigged version of the same boat." They would sacrifice a bit of windward performance, pay a bit more, be able to get under a few more bridges, need a little less beam, and buy smaller winches. They would also have a prettier silhouette, have more sail choices for reefing, and be able to balance the rig under a wider range of conditions. The flip side is this: There aren't that many experienced couples in the market for a Schooner rigged multihull that costs more and sails slower, no matter how pretty it looks.
     
  9. rayaldridge
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    rayaldridge Senior Member

    In an old book, _Multihull Seamanship_ by Michael McMullen, the author argues for breaking up the necessary sail area with a ketch, schooner, or yawl rig. Of course, the single stick boat with the same sail area will be more efficient overall, but I've always wondered why cruisers don't seem to appreciate the many advantages of a divided rig, especially for a multihull.

    One thing McMullen said that I've wondered about is that tris are better suited to two-masted rigs than cats. I don't have the book to hand but it was something about tris heeling more.

    Frankly, if i were drawing a big multi, I'd be very inclined to go with a divided rig. As Eric said above, two masts cost more than one mast, but winches and other components can be smaller and cheaper, so I don't know how much money a single mast saves.
     
  10. robherc
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    robherc Designer/Hobbyist

    Please, everyone, I like the way this conversation is developing...keep the info (however limited) flowing as I'm still in the "early research" phase of my 3-masted trimaran project.
    I'm designing mine with a goal LOA of about 76' and BOA of about 44'. I'm designing the boat to be a (fairly heavy) trans-Atlantic cruiser & decided on the trimaran design to add heeling stability (for my wife) without sacrificing as much interior space as is lot when using a cat.
    The (read: MY) theory behind the 3-masted tri would be to lower the CE as much as possible, thereby further reducing heeling moment & allowing a smoother ride on calm days. (not to mention having FAR lower strains on the masts/rigging, and making the sails MUCH lighter & easier to handle).

    I'm eagerly reading everything posted in here, and trying to assimilate as much knowledge as possible into my forming design. :)
     
  11. marshmat
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    marshmat Senior Member

    76' LOA, 44' beam... that's one heck of a boat, Rob!

    Keeping the sheet loads and sail weights down to what one person can manage seems (to me) a potentially very valuable result. I shudder to think what might happen if the sheet for an 800 square foot genoa were to get away from its #54 (or whatever) winch. Not nearly so worried about a setup with 1/3 to 1/2 of those sheet loads, even if there do end up being a genoa and two or three mains on masts to deal with. And a cat/tri with its insane righting arm has the real possibility of the sheet loads skyrocketing in a gust.

    So if we're not as concerned about flat-out speed upwind and are more interested in sensible cruising (just at a faster pace than our friends in the lead-bellies), and aren't interested in the best new racing hardware, what would we like to see in a two- or three-masted multihull rig?
     
  12. robherc
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    robherc Designer/Hobbyist

    Hmmmmm....

    1. Look pretty
    2. Good stability on virtually any point of sail (besides DUW or DDW, of course)
    3. Multiple, balanced, trim options (maybe strike the main & sail with only foresail & mizzen in moderate-heavy winds)
    4. Lower rigging & sail tensions, so 1 sailor can more easily handle them NON-electronically!
    5. Ability to sail in worse conditions, should you get caught in them, than lighter multi-hulls.
    6. (for my "big one") Room to store LOTS of provisions for crossing Gulf of Mex+Atlantic+Mediterranean w/o being forced to stop & take-on supplies.
    7. Did I mention, LOOK PRETTY ;)
     
  13. yipster
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    yipster designer

    longtitudal that was / is right? any pic's?

    here the biggest unstayed masts ever again to awe.
    [​IMG] [​IMG]
    team philips was about the ultemate multimast cat i figger. the reefed unstayed masts naturally stayed up but kept the cat running fast in roach waves of an unexpected 12 atlantic storm. port bow was repaired before and it was damage to the bottom of the middle pod and expected loss of steering together with a further deteriorating wheater forecast that made the team decide to mayday and abort. during and after the boat got total loss. wave piercing on the big cat was good i read but it surprises me the high mounted pod got damaged, spout enough and i wonder if for more normal bridge deck cats a through hull scupper system and a middle hull a la incat would behave in such extremes. the inability to strike or telescope down the drag of the bi surf sail config rig kept the cat running at some 30 knots but otherwise it seems the rig was great. there are only some 5 or 6 ways to change 2 planes against each other and as long as there is 1 cord space in between there should be minimal effect on changing positions and wash between them, at least that goes for biplane aircraft i read. team philips became a dramatic monster that never showed its full potential, Pete (with Adrian?) promised to write a book about the adventure and boat specifics and i hope it is gonna reveal more of the concept as this boat was a great example for multi masted cats. for now, its reading testing and see what will happen in time...
     
  14. sandy daugherty
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    sandy daugherty Senior Member

    I'm afraid that when you get down to real quotes and accurate figures for specific equipment, that this concept will hit the dollar barrier very quickly. Since the cost of a sail is actually in the labor and fittings, One big sail might cost a good bit less than two half-size sails. Since multiple masts mean multiple shrouds, tangs, hardpoints, hounds, halyards, goosenecks, masthead sheaves and sheav boxes, etc., you've spent a bunch of bucks before you've bought winches. Then you have to break up the living space with bulkheads to support the masts and carry the loads out to the shrouds, it could quickly become and exercise in frustration.

    So add another term to the small builder's list of troubles; before "unobtanium" (a material required to manufacture an essential structural element) insert "nonaffordability" (an essential concept so expensive that it dooms the dream at the first sigh.)

    What really grits my teeth is the fact that these factors approach do-ability as the size of the vessel gets bigger. A seventy foot tri might need an 80 foot single mast, but could get by with two masts totalling that length.

    The point arises; if you dream of a gaff-headed schooner, why not just go get one?
     

  15. Tad
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    Tad Boat Designer

    As always the cost will vary with the details.

    An 80' tube with rod rigging and hydraulics to match is a bunch of bucks. But you can build a 50' wood/carbon spar and splice up the synthetic rigging to suit. Shorter spars and smaller sails mean lower loads, smaller rigging, smaller blocks, winches, etc. Smaller stuff is far easier to find on sale/used/thrown out.

    Things can be accomplished by ignoring the West Marine/Harken/Lewmar solution and making your own stuff.....it will be far more reliable. Sailors have even been known to build their own sails.....it can be done!
     
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