Small trimarans under 20'

Discussion in 'Multihulls' started by Doug Lord, Jun 24, 2012.

  1. Doug Lord
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    Doug Lord Flight Ready

    I accidentally discovered today a foil idea I had in 2012 for use on a multihull sailing in very shallow water. It would make it possible for the Fire Arrow to get most of the benefits from ama foil lift in 1' or less water. Basically, it's DSS for multihulls-I talked it over with Hugh Welbourn(inventer of DSS) and he agrees it could work well. The foil was originally conceived of to be fastened to the bottom of a small flat bottom ama, but if I was to do it I would make it so it fit the Fire Arrow trunk and it would be able to be adjusted vertically a small amount. So, depending on what course looks feasible in the Everglades Challenge this foil might replace the UptiP ama foils for this race. The foil would not be fully retractable but because the amas are a few inches above the water when the boat is level, de facto retraction happens by simply leveling the boat. There are other challenges to make the Fire Arrow suitable for the Everglades challenge but a potential big problem has been solved. One disadvantage of this shallow T-foil is that it would increase the beam from 22'(with UptiP ama foils) to about 26' with these foils.
    For the Fire Arrow the foil would simply be a T-foil inserted into the ama foil trunk and designed to operate close to the bottom of the ama. It would be designed to lift 80+% of the weight of the boat in relatively shallow water with a little help from the ama. Not as good as an UptiP foil but good enough to allow lots of speed in shallow water.
    ==========================
    UPDATE: For those that may not be familiar with DSS it's important to emphasize that the T-foil in the sketch is not just any T-foil- it's set-up to operate close to the surface and to the bottom of the ama.
    The separation shown between the top of the foil and the bottom of the ama is probably the maximum that would be used. More separation and the foil would have to be smaller or have a flap and an altitude control system. Operating close to the boat and close to the surface it doesn't need any form of altitude control.
     

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  2. rcnesneg
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    rcnesneg Senior Member

    Back on topic here guys, What trimarans that have actually sailed would you consider potential beachcat or racing catamaran killers? A few come to mind, but I'm sure I'm missing a few, and some of these may not actually perform as good as I think.

    There are also a myriad of 23 ish foot trimarans that could probably kick a F18s butt, and possibly beat a tornado.

    Sizzors, from the Everglades Challenge:
    [​IMG]

    This thing, No other info for it:
    [​IMG]

    Mosquito:
    [​IMG]

    Ultralight 20:
    [​IMG]

    Akila 19:
    [​IMG]

    And then a few foilers

    Broomstick:
    [​IMG]

    Kotuku:
    [​IMG]

    Windrider Rave:
    [​IMG]

    Osprey:
    [​IMG]

    Trifoiler:
    [​IMG]

    The prototype Hydroptere(s) from back around 1990:
    [​IMG]


    It seems to me that they are all doing one of two things, either outright beating the catamarans at their own game, by producing tons of righting moment on a lightweight platform with lots of power, or going full foiling and playing the mini hydroptere game. What's your take on this?
     
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  3. waynemarlow
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    waynemarlow Senior Member

    Doug I'm trying to give you sage adult advice, sadly over the years many have tried and failed to get you to understand that the best designers and contributors to these type of forums offer considered ideas rather than the shotgun approach that you adopt of just thinking up any idea and immediately publishing it.

    Perhaps if you were to limit yourself to just one post per day and spent the remaining time that you would have spent at the keyboard developing properly those ideas, your ideas would be better received here on these forums and just maybe would be integrated into main stream sailing.

    For all your personal revolutionary ideas, sailing design is just an evolutionary process and I would suspect that all that has been discussed on this long thread has been well and truly tried and tested by somebody somewhere. You are just a very small spoke in this very large wheel, never less important than all those others, then let those others have there say without the immediate Doug Lord response.
     
  4. Richard Woods
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    Richard Woods Woods Designs

    You should include my Strike 15 in that group. One owner wrote:

    "Last Sunday during a three rounds regatta with 6 to 7 kts winds I was behind A class cat and Tornado with spinnaker, sometimes very close or ahead of the last A cats (despite my very bad starts !), but I consistently beat all the rest of the fleet including Darts (both 1 and 2 up). I pointed as high as A class cat upwind, but slightly slower. Faster and closer than Darts upwind, faster and deeper downwind (main and jib only)."

    So that isn't a "I did 15 knots" or "I think it will be faster than X" sort of claim. This is actual results from boat to boat races and remember it is a 15ft boat, not 18 or 20ft.

    See more here

    http://sailingcatamarans.com/index.php/designs/27-trimarans-under-25/223-strike-15-trimaran

    My own Strike 15 is for sale BTW, USD4000 on a trailer

    To Doug, your shallow water device won't work in any waves will it? And I see from my powercat research that tests show that at least some powercats gain no benefit from foils. So it isn't a "go fast" for everyone

    http://www.hookedonfishingboats.com/hydrofoilsoncats.html

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  5. Doug Lord
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    Doug Lord Flight Ready

    ============================
    Richard, since it is very similar to DSS and that is proven in all conditions- I'd say the chances are good that it would work well. One thing Hugh Welbourn told me is that the foil can work as a typical lifting foil but still generate a lot of lift just as a planing surface. But you never know until the specific application is tested. It hadn't occurred to me until right now but we could do a preliminary test on the model very simply. Thanks for sparking the idea.
    The power cat stuff is interesting-do you have any links, pictures etc of what was tested? And how?
     
  6. Doug Lord
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    Doug Lord Flight Ready

    ==========
    rcnesneg, I've seen all the other boats but not the Akila-do you have a link for that? Good post, thanks!
    I can't remember the boats name now, but in 1969 a C Class trimaran beat all the C Class cats a couple of times.
    And another Gougeon brothers tri nailed the Formula 40 catamarans.
    Tris definitely have the potential to beat beach cats but they don't have the reputation of doing so-mainly because stuff like this has been ignored and under 20' tri's have, for the most part, not been designed to compete well with beach cats. It certainly isn't that they couldn't it's that their designers chose another path.
    Many of the tri's that have been built under 20' are really great designs-and do what they were designed to do. My 20' tri in 1971 was great fun with its planing main hull but now I consider it a low key fun boat -definitely not state of the art. I'm looking forward to seeing more state of the art "Super Tri's" around-it will be a good option for many sailors. Akila looks like it might be-I'd love to see the numbers.......
    Found a bit more here. So very frustrating when the numbers aren't published! http://smalltrimarans.com/blog/?p=11034
    -----------------------
    For anyone interested in foilers, the largest gathering of foilers in the history of the world is taking place now in Sorrento ,Australia. Races start at 9PM EST-see the "Moth on Foils!" thread in the "Sailboats" forum. http://www.boatdesign.net/forums/sailboats/moth-foils-35-9-knots-41-29-mph-11209-100.html#post720608
     
  7. Richard Woods
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    Richard Woods Woods Designs

    :mad:
    I didn't know the DSS had been tested in "very shallow water" what boats were tested where?

    According to the first line of the boat test I gave you the boats were 3660 Pro Sports Pro Cats

    RW
     
  8. Doug Lord
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    Doug Lord Flight Ready

    Richard, sorry, my answer was that DSS has been tested in waves-I don't know about shallow water and waves. Just how shallow and in what wave conditions the t-foil will work will have to be tested full size. Hugh thought it should work well.
    I would much prefer to sail in enough water to use the UptiP foils but I think the shallow foil has potential.
    --------
    Didn't see the report-I just read it and wouldn't put much stock in it since it was so limited.
     
  9. waynemarlow
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    waynemarlow Senior Member

    Richard

    Be a little wary of quoting against the A Class at 6 - 7 knots of wind, they have a very high aspect rig and relatively small amounts of sail area. Yes they do go well upwind but from experiance, will be absolutely dogs downwind and on a beam reach at that wind speed.

    The second boat in the series of photographs was a professional designers attempt at building a mini Tri with very narrow but high floats ( sort of what Doug had drawn a few post back ) to try and minimise the water line drag at planing speeds but with ever increasing bouyancy should the Tri heel. It used an F16's carbon rig weighed about 90kgs all up and sadly didn't really live up to its potential, I'm not sure why.

    For a small racing Tri at about the 20 ft level it is always going to be hard to beat the dedicated racing beach cats who can from about 7knots of wind speed and crew placement, fly one hull. The Tri's on the other hand will be dragging two in the water unless they have a larger proportional sail area, to use the additional RM and fly two hulls. At that point any handicap system used for racing will penalise the additional sail area and the Cat will win. Yes if you're only keen about first over the water you may get a Tri win but with equal sail area there will only one winner.

    For me why reinvent the wheel, the 20ft Tri just ain't goner be a race winner, so why not head towards where it is ideally suited, a good load carrying day sailor capable of doing some semi offshore races, with a small cuddy to carry the sandwiches and offer some protection if needed.
     
  10. Richard Woods
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    Richard Woods Woods Designs

    Of course the original question didn't specify wind strengths or which beach cat, so my comments still stand I think. And that Strike owner is also an A cat sailor so has personal experience with both boats.

    Like many other small trimarans the one going past Jack in the Basket has outriggers that are too short. They are still hulls in their own right so that lee hull is going real fast relative to its length, so lots of drag.

    That's why I drew long narrow outriggers on my Strike 15

    Otherwise I agree with your comments especially the last paragraph. For sure the trimarans are more comfortable to sail. The better comparison would be to compare a 20ft trimaran with say a J70 or Melges. Why do people buy those boats when a trimaran is quicker?

    Richard Woods
     
  11. Doug Lord
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    Doug Lord Flight Ready

    ====================
    Given the history of high performance tri's vs high performance cats, I think this is wrong.
    The latest example was "Sizzor" beating a Tornado* in the 2014 Everglades Challenge(for the second time-he did it in 2011 as well). For you, nice and easy is fine as it is with many people. But there are others who want their tri to be faster than a beach cat, comfortable and easy to sail. And a fast and comfortable tri doesn't necessarily need foils or a square/oversquare beam to beat the best beachcats! It's a matter of design......
    * http://smalltrimarans.com/blog/?p=5132
    Randy quoted in 2011:
    Sizzor offers plenty of speed but it also is an extremely dry ride and very comfortable. When Iā€™m sitting at the end of the hiking rack I am over 2 feet above the waves. For the 1200mi. race it has an autopilot that can operate when I nap in the comfortable hammock trampoline at reduced speed. ...


    Sizzor specs:

    LOA-20' +20" sprit
    BEAM- 18'
    MAST-26' A-class mast
    SA UPWIND-185 sq.ft.
    DOWNWIND-337 sq.ft.
    WEIGHT-168lb.
     

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  12. rcnesneg
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    rcnesneg Senior Member

    For the Akila 19, this is all I got. http://smalltrimarans.com/blog/?p=11034

    As for hull flying, I don't see why a Trimaran can't fly two hulls in 7 knots of wind. Just pack more sail area, I don't see anything wrong with that, and have the person sit on the leeward side of the boat. They aren't catamarans so there is no reason to stick to cat-sized sailplans. That's the beauty of the tri, it CAN carry the bigger sail area. So lets use it.
     
  13. Doug Lord
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    Doug Lord Flight Ready

    ---------------------
    Be careful there,rcnesneg: note Sizzor's sail area and sailing weight compared to a Tornado! A trimaran can allow very efficient design and/or very powerful design-or anything in between-like I said before-it's a matter of design. Note that the sailing weight of Sizzor is less than half of the Tornado.
    Given your main hull you might do best to stay toward the very light, efficient side of the design spectrum-you can still whup beachcats! Sizzor is just a little heavier than an 18' A Class cat with about 20% more upwind SA and 224%(!) more downwind sail. When you consider amas look closely at Sizzor and constantly check your projected weight.
    --
    Earlier,I mentioned the Gougeons tri that won the "North American Multihull Championship" in 1969-it was "Victor T". It was a C Class(the original C Class had no beam restriction) with an LOA of 25' ,18' of beam weighing just over 300lb.
    --
    Tornado 356lb boat weight +175+175(2 crew)=706lb
    SA upwind: 236.2 sq.ft.
    SA downwind: 505.3 sq.ft.
    =======================
    Sizzor-168lb boat weight + 175(single crew)= 343lb
    SA UPWIND-185 sq.ft.
    DOWNWIND-337 sq.ft
     
  14. rcnesneg
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    rcnesneg Senior Member

    That is very true, the massive beam allows hiking a long way out, so large amas are not necessarily required. I think I need to find a way to seal the tops of my amas and redo the trampoline so I can hike all the way out, along with an efficient sailplan. I think I'll ditch foils on the amas for the time being and see what I can get out of the rig I have now.
     

  15. Doug Lord
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    Doug Lord Flight Ready

    ==============
    Something else to consider: if you use a short ama designed as a displacement hull, then it is likely to cause considerable drag as the main hull starts to speed up. But if you design the ama for planing, then the drag will be less as the mainhull accelerates.
    By applying a bit of careful design, you can use smaller amas(with or without foils) successfully which will reduce the all up weight of the boat.
     
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