Small trimarans under 20'

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

  1. rcnesneg
    Joined: Sep 2013
    Posts: 456
    Likes: 6, Points: 0, Legacy Rep: 58
    Location: Utah

    rcnesneg Senior Member

    So therefore, from that reasoning, tornado < sizzors < nacra 17 spi. LOL
     
  2. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 346, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Main hull foils

    No, no-we've been sidetracked by ratings stuff which I will learn about but enough in this thread.
    --
    I want to mention a part of the design of my Fire Arrow that I think offers a lot to high performance trimaran design.
    That is the concept of using lifting foils on the main hull of an almost square, square or over square tri-regardless of whether or not the tri has foil assist, planing amas or full flying amas and regardless of ama size.
    The cool thing is if you use a properly designed wand controlled main foil with a trailing rudder T-foil this kind of boat can fly the main hull in as little as 5mph of wind(4.35 knots) instead of the 12 -15 knots it could take otherwise.
    As the boat begins to speed up the the ama and/or ama foil will begin to take more of the load causing the main foil to unload, reducing induced drag a lot.
    As that happens, the full power of the main foil + rudderfoil automatically controls pitch with far greater control power than is available to a tri w/o these foils. Further, the mainfoil wand system will react to any gusts by increasing righting moment instantaneously.
    It's a system like this that makes an, almost square, square or over square trimaran practical allowing the boat to fly the mainhull early as well as to develop the awesome righting moment such a boat is capable of.
    The fact that this system drastically improves the light air performance of a wide trimaran is one of its greatest attributes in terms of using such a boat in the US where light winds seem to predominate at many venues.
    Combining that with the systems' automatic control of the angle of heel and
    the ability to generate huge amounts of extra RM when needed you wind up with a boat that can sail fast in light or heavy air with exceptional control.
    This is a system that could make a beach cat hunting tri practical while having great comfort and sea-kindliness.
    It's the foil system used on the main hull that is the key and it is applicable to a wide range of trimaran designs.
     
    Last edited: Jan 13, 2015
  3. rcnesneg
    Joined: Sep 2013
    Posts: 456
    Likes: 6, Points: 0, Legacy Rep: 58
    Location: Utah

    rcnesneg Senior Member

    Wouldn't it be lighter to just narrow the beam and shift weight to leeward? The main hull foil system would not be useful above 15 knots, except maybe for stabilization, correct? How does the system have automatic control over heel?
     
  4. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 346, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    That's the beauty of a wand altitude control system on the main hull of a tri. It doesn't just control altitude like on a Moth or on Osprey it also controls the angle of heel of the boat. The wand is a simple surface sensing device, when the main hull is in the water, the wand is all the way back causing the flap on the main foil to go max down=max lift. As the boat speeds up the wand reaches a neutral point so the flap is not causing extra lift, but if the boat sinks a little the wand lowers the flap to increase lift, and if the wind should cause the tri to heel past the designed neutral point,the wand raises the flap and that causes downforce=gust response/extra righting moment.
    The system works throughout the windrange: when its light air the foil lifts the main hull, when windpower begins to support the main hull the wand allows the main foil to be unloaded, reducing drag. When the wind really picks up the wand adds righting moment(downforce).
     
  5. rcnesneg
    Joined: Sep 2013
    Posts: 456
    Likes: 6, Points: 0, Legacy Rep: 58
    Location: Utah

    rcnesneg Senior Member

    Ahh I get it! What if you are relying completely on the wand and center foil for a lot of downforce, and you happen to go through enough chop, say caused by the same wind pushing the boat, that the foil comes out of the water in a trough between waves, and you lose downforce? Wouldn't the boat heel uncontrollably, possibly leading to a capsize? I feel like the Hydroptere system would be much more reliable, and it also allows full foiling, so you don't need the leeward hull to plane either, which would be all over the place in the waves.
     
  6. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 346, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    wand

    The fact that this concept works is 100% proven already with my Test Model because the wind was so light(5mph) for the last video that if it wasn't for the main foil lifting the main hull it would not physically have been ably to fly!
    That is a point initially missed by 90% of the people that look at that first foiling video.

    Here's a control animation of the wand controlling a foil on Dr. Bradfields Rave. Note that at the top there is a shockcord that holds the wand against the water:
    https://www.youtube.com/watch?v=yuFwDm8t3IM
     
  7. rcnesneg
    Joined: Sep 2013
    Posts: 456
    Likes: 6, Points: 0, Legacy Rep: 58
    Location: Utah

    rcnesneg Senior Member

    But what if the foil comes out of the water for some reason, say a wave? Then you have no downforce, right?
     
  8. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 346, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    --------------------------
    That's a matter of proper design and seamanship. The foils are designed to be submerged deep and if you were sailing in conditions where there was a remote change of the foil popping clear you would need to back off. In 99% of sailing that would never be a concern.
    The Hydroptere system requires movable ballast and special treatment of the foils to prevent ventilation. It also is not an ideal system for upwind flying because of the angle of the foils. It takes a 12-15 knots of wind for Hydroptere to fly.
    My system does not require that the whole boat is flown-you can use a "normal" well designed ama and the system will allow the main hull to fly in very light air. For greater speed the use of UptiP foils on the ama is the way to go.
    --

    Pictures-Look at how deep the foils are(about the same as a Moth, but these are retractable on the fullsize version). The picture with my crew Dan illustrates how deep they are and the next picture shows a "pitch up" in the second video when the rudder was too sensitive and the wands too long that resulted in this great shot. But even as high as it jumped notice that the main foil and rudder foil were still submerged! The only thing keeping it in the water, at that point, was the main foil downforce. The system allows you to adjust your flying altitude to suit the conditions.
     

    Attached Files:

  9. RHP
    Joined: Nov 2005
    Posts: 836
    Likes: 87, Points: 28, Legacy Rep: 1183
    Location: Singapore

    RHP Senior Member

    You guys are talking way over my head but it's interesting all the same and highlights the fact we're lucky enough to have 2 great 20' trimaran designs out there are reasonable cost already for the average man to buy: the UltraLight 20 and Searail 19. (Plus Richard's Strikes as well of course).

    There will always be folks who want to go faster, lighter or fly but for the majority of us, the ability to go fast in a manageable boat is simply one cheque signature away....
     
  10. 2far2drive
    Joined: Nov 2011
    Posts: 116
    Likes: 11, Points: 0, Legacy Rep: 82
    Location: Houston, TX

    2far2drive Senior Member

    well we've been pulled back on topic... of foiling again somehow. and doug has reposted (regurgitated) the same thing all over again in post #272 that he has said at least 500 times back over in his own thread.

    can we not stop the blatant thread pollution with your own horn tooting sir?

    as far as Im concerned, you have 100% proven ****. come back to me in a year with solid hours of video of non stop flying and a little less ego.

    the saddest part, i think foiling, especially your fire arrow design, to be the coolest thing in the world. I have even considered building something, going ultra light and consulting you on foils to get something to fly and make you be quiet. you kill it for me. absolutely 100%. screw foiling. you've oversold it. we get your point. now, please be quiet and let this thread progress.
     
  11. upchurchmr
    Joined: Feb 2011
    Posts: 3,272
    Likes: 250, Points: 83, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    If you think Searail and Ultralight are reasonable cost I need to quit dreaming.
     
  12. upchurchmr
    Joined: Feb 2011
    Posts: 3,272
    Likes: 250, Points: 83, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    2Far on the same subject.

    Just add something besides whinning about Doug. Then we can all get back to the subject.

    What would happen if no one talked about his repetition?
     
  13. RHP
    Joined: Nov 2005
    Posts: 836
    Likes: 87, Points: 28, Legacy Rep: 1183
    Location: Singapore

    RHP Senior Member

    Can you explain why you think $20k is unreasonable. Factory investment, tooling, overheads etc.. what am I missing that negates those costs?
     
  14. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 346, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    =======================
    I have proven that the mainhull of my test model will fly in wind too light for it to fly other wise. I have proven that well designed UptiP foils will work on a trimaran. That's fact. There's still plenty of refinement left to do.
    ---
    I think it's terribly unfortunate that you let your "love" of foils be affected negatively by anyone-and it seems very weird.
    My post on flying the main hull was not a post about the Fire Arrow-it was about the part of the Fire Arrow system that has the widest potential application to other trimarans and is most definitely part of the subject of this thread which is trimarans 20' and under.To call that thread pollution is nuts. If you'd just think about it you might see the potential -not of the Fire Arrow- but of a system that allows the main hull of a wide trimaran to fly in light air.
    You seem totally unable to discuss any part of the subject matter as an adult and that's too damn bad.
    ---
    I am sorry for you that you can't separate your venom towards me from a realistic look at the potential of a system that allows a wide trimaran to function better. It
    seems to me that such a system has tremendous potential and rather than attempting to patent it or any part of it I'm publishing every detail so that it might help other people. Again, the subject of post 272 is NOT the Fire Arrow but it is about using modern ,widely available technology to help improve the trimaran platform.
    If your objection is to me even mentioning anything to do with foils then you're just flat out of luck because I consider the application of foils to high performance small trimarans to be absolutely critical to improvements in speed, ride comfort and sea-kindliness. If you could disassociate your dislike of me from your mindset and discuss this stuff intelligently without the personal attack bs, we might get somewhere. But if you think I'm not going to discuss the application of modern foil technology to small trimarans then you are very much mistaken.
     

  15. waynemarlow
    Joined: Nov 2006
    Posts: 432
    Likes: 45, Points: 28, Legacy Rep: 134
    Location: UK

    waynemarlow Senior Member

    Its interesting that Bethwaite wrote the following

    "First we towed only real hulls which were ballasted to real weights. We never trusted models because such unpredictible things happen in the scale change from model to full size. Even the most experianced workers still sometimes get this scale change factor wrong "

    I do suspect this maybe the case with the the Fire Arrow unfortunately and until the model is built full scale I will remain a fence sitter. It has its own thread and perhaps the time has come to only mention its ideas in that thread until it is built full size.

    Doug why not restrict your continued enthusiasm for your models to just the threads related to the models, at the moment the continual bringing up of foils and all things related to your models is actually resticting development of ideas in these threads, probably the very last thing you actually want to happen.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.