Design Challenge: Trapwing-"on-deck" ballast-12'-22'

Discussion in 'Sailboats' started by Doug Lord, Oct 7, 2009.

  1. Doug Lord
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    Doug Lord Flight Ready

    I have always wanted to sail a boat like a 2.4 Meter but with much higher performance. I suggested a concept years ago and wonder if anyone else has any thoughts on how to make something like this work or improve the concept.
    The idea I had was to use a molded "wing" that would have ballast slide inside it to give large RM-similar to a two handed dinghy where one of the crew is on a trapeze. The ballast could be moved by hand, foot power or electrically. The boat might have a small fixed keel. The ends of the "wing" would be slightly larger in section to provide extra buoyancy. Each side of the wing would be supported by a "trapeze" wire making moving the whole wing(and the ballast inside it) fairly easy since it all moves horizontally.
    The idea is to sit in the boat like a 2.4 meter but plane(or foil depending on design) early and fast.
    I'm interested in any ideas that would accomplish this in a relatively small POSSIBLY self righting monohull....

    Personally, a boat that would sail like a Windmill- with me sitting in the center- would be cool. That boat planes in 10 knots or slightly less and is a great ride offwind in a breeze. But a boat could be built that would be a bit more powerful and meet Bethwaites criteria for upwind planing(foiling):
    LOA 16'(or so)
    SA-around 160 sq.ft. upwind
    12' sliding "trapwing" with 160 lb ballast
    All Up boat weight minus wing,wing ballast and keel ballast including rig:160lb
    75lb keel bulb
    130lb-180lb crew
    SCP/Total Weight=30% @ 180lb crew

    As I envision it the wing+ballast is supported by trapeze wires-side to side movement would not require a whole lot of effort....
    Just as a rough illustration here is a picture of a Melges 24 and microMOTH model fitted with a "trapeze power ballast system". The battery was part of the sliding ballast and that could be done on a full size version. The "wing" on the model is just two carbon tubes that form a track for the ballast to slide on. To me, a molded,sealed, wing on the full-size version would have a number of advantages including lower aerodynamic drag, buoyancy and it could be built with a slight curve.
    A well designed, tested and proven version of this boat(that was self-righting) COULD offer disabled sailors(and/or grumpy old men like me) a high performance single-handed alternative to the 2.4 meter.
    The previous thread on this topic wound up being locked and that was unfortunate. So some of the contributions made there including the viability of an electric powered sliding ballast system will be reintroduced here. I am in the process of building a platform for this concept (one of three experimental ideas I will test over the next five years using the same basic platform). From continued study and working with this concept it appears that at around 22' a version could be done that would be capable of fairly high speed on foils since it will be extremely aerodynamically clean-just more potential for a very interesting concept.

    BUT,and this is important: to be viable this boat does not have to be suitable for disabled sailors! Don't view this concept ONLY thru the lens of what might be suitable for disabled sailors.
    Here's a pix of the models with the movable ballast system supported by trapeze wires:
     

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  2. Doug Lord
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    Doug Lord Flight Ready

    12' Trapwing-no foils

    Ballast sliding in sealed wing and moved by hand.Wing supported by trapeze wires. Not selfrighting. No hydrofoils. Not suitable for disabled sailors-probably.Much faster than a 2.4 meter and lots of fun to sail-I think.Planing hull. Sealed wing slides side to side and lead inside wing also slides.
    Very Rough sketch of this version of the concept:
     

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  3. Doug Lord
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    Doug Lord Flight Ready

    14-18' Trapwing

    Single hander with more power and faster than a 12' version. Possible use of foil assist. Electric or manual ballast movement. Possible small keel for a self-righting version in this length range. Planing hull. Can be designed for upwind planing. Sealed wing slides side to side and lead inside wing also slides.
    Very Rough sketch of the concept:
     

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  4. Doug Lord
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    Doug Lord Flight Ready

    16-22' Turbo Trapwing-High Performance

    Singlehander for highest performance. Electric or manual ballast movement. Can be designed to be self-righting. Can be designed to use lifting hydrofoils.
    Design can be optimized with enclosed cockpit in non-self-righting version for potential high speeds on foils-largest version only(not suitable for disabled sailors). Self-righting version suitable for performance oriented disabled sailing is possible. High L/B hull. Sealed wing slides side to side and lead inside wing also slides.

    Very Rough sketch:
     

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  5. Doug Lord
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    Doug Lord Flight Ready

    Steve Clark comments on Trapwing:

    From a man I respect a great deal from the previous thread:"My guess is that anyone who has tried to build model boats that feature "real life" performance has had ideas along these lines. Almost half of the models I built as a kid had some sort of movable ballast systems to make them sail faster in the typically windy place I lived. Because RC gear was beyond my means, I never tried to make a remote controlled shifting ballast system until I was over 45 years old. But I do have to admit that I had canting keels and racks that held ballast packages well out to windward, and sometimes these models went stupidly fast.
    Could this be scaled up, probably but I am pretty unhappy with the so called "trapwing" concept that is being promoted. At least as portrayed in the images of model boats shown and from Doug's descriptions. I think it is awkward and that the difficulties outweigh the potential benefits.
    Many people have come to me with versions of this over the years, and I haven't seen one I liked.
    It is also worth noting that there were ballast carts on many cruising boats around Narragansett Bay in the mid 1800's. (Herreshoff"s Clara for one) This feature was not maintained as time wore on, I suspect because the kinetic risk of having a rail car full of a few thousand pounds of lead helt to the high side by a a pawl or equvalent mechanism was pretty disquieting. I know of no record of disasters, but I would have been pretty careful around these things. Talk about lose cannons!
    However it is also fairly obvious to me that a faster version of the Martin 16 is possible. One has merely to refine away some of the compromises and make the obvious improvements to specifications to achieve that.
    One important parameter is how much body shifting is acceptable within the notion of "sitting inside." Just being able to shift your bum or roll your shoulders to windward could be a significant increase in sail carrying power. So mobility within the constraint of "sit inside" needs further examination.
    So while I don't see any reason why there can't be sit inside boats that sail very very well, I don't like the above deck shifting ballast system as proposed."
    SHC
    ------------------
    And once more:

    " Doug:
    Have you examined the difference between the two arcs made by the trap wires and created a hull/ wing containment that resolves them and is capable of what can be significant upward shock loads ( smacking waves) and fore and aft shock loads ( smacking pilings.)
    Have you also resolved the conflict between the leeward (still tight) trap wire and the mainsail. As I see it if the leeward wing is to not extend beyond the leeward gunwale, there will be no way to ease the mainsail very far without centering the wing and sacrificing righting moment first.
    Maybe that's why it has to be self righting!

    Finally, having spent most of my adult life handling narrow boats with movable hiking extensions that slide through about 7' and extend about 3' from each rail when centered, I can assure you that handling these boats near docks and floats is a real challenge and a limitation for the concept. In the case of the IC, athletic sailors can compensate for a lot of inconvenience for performance, but otherwise it constantly limits where and how we sail the boats.

    The freeboard of the float, for example, makes a big difference in how you approach and depart. Things as simple as sailing by a motorboat to pick up a water bottle are easily twice as hard as they are in a normal trapeze dinghy.

    If this boat is supposed to be a fast boat for geezers and the less mobile, you have to think carefully about how one gets aboard and how one maneuvers and docks. Outriggers of any kind make this more difficult than otherwise.

    In all of this, based on my experience with International Canoes, will be harder with an above deck sliding outrigger than with any of the existing alternatives. As such, even though I believe such a system is possible to construct I don't believe it is practical or attractive. Therefore, I believe its merits are not worth further research."
    SHC
    =====================================
    My response from the previous thread:
    ---
    Thanks for the comments Steve. I've given quite a bit of thought to how the trapeze wires work and to what extent they interfere with the main.
    First, this was worked out on the models by:
    1) having the trap wires go to the end of the racks,
    2) having the whole ballast assembly mounted pivotably athwhartship,
    3) having the trapwires adjustable,and
    4) when the wing/rack is centered neither trap wire is tight but the wing/rack end is supported by shock cord-the whole thing is completly adjustable.
    That's where we'll start on the full size boat.
    As to shock loads on the full size boat-one idea is to have a line from the bow aft to the wing outboard rigged in such a way that the wing can move side to side but is reinforced against shock loading directly aft-as in a wing/wave impact. Need to look at athwhartship pivoting shock loads as well.
    ---
    This boat is conceived of to be easily beach sailed. In Florida, we have loads of launch areas for a boat like this. The docking thing will be a problem-no doubt-we'll just have to see what kind of work-arounds can be found with experience on the water.
    As to the viability of the boat for disabled sailing-it appears to be suitable theoretically, in some versions ,after talking to several disabled sailors. But that will need experience on the water to know for sure. I'm not at all sure that the Turbo version discussed in this thread will be ideal for that application but a couple of guys I talked to are excited by the idea. We'll see-soon I hope.
    -----------------
    I completely disagree with your conclusion that the problems you mention disqualify this concept from further development-but I very much appreciate your willingness to present them. Thanks. Only by studying, carefull design/building and testing a prototype can we know for sure. And, there are YEARS of model testing of boats that were skinny to wider boats that suggests that these problems can be solved.
    ====================
    These comments are presented to give an idea of both the intelligent, well thought out criticism from Steve and my response from the previous thread. This is an idea that I think is worth some discussion and experimentation which I have already done a lot with on models. I'm interested in hearing any well reasoned comments, suggestions or similar ideas.
     
  6. Doug Lord
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    Doug Lord Flight Ready

    Charles Herreshoff and Sons-on-deck ballast!

    I just found some details about a story that I'd heard a few years ago-about
    "Herreshoff" experimenting with on-deck sliding ballast.
    This is from a book "Herreshoff Sailboats" by Gregory O. Jones and lays out some interesting details of the first recorded use of on-deck iron sliding ballast that I've been able to find. Apparently, new rules and sheer terror got in the way of further development though the two boats that used this form of ballast were very fast. The Seawanhaka Corinthian Yacht Club, formed in 1871 banned movable ballast.
    Charles Herreshoff built four "Julias" ,the second was outfitted with an athwhartship track for 550lb. of iron ballast to slide. The method was to release the ballast from the windward side and allow it to slide to leeward just as the boat tacked. Charles designed a larger boat "Kelpie" that his two sons built that used a larger sliding ballast system-1000lb! Kelpie was very fast.
    This stuff is exciting to read about and one can only speculate how these systems might have been refined over the years. I think modern versions of systems like these using lead or water have a tremendous potential in high performance boats of all sizes. I'm going to concentrate on small boats where I see an exciting opporunity to explore this interesting technology.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    Trapwing Test

    After rereading some of Steves comments here and on SA AND reading and re-reading the inspiring Herreshoff story I've decided to do a test version of the Trapwing system using almost the same system that you see on the models above. That is, instead of using the molded wing I will use carbon tubes with a "ballast module" sliding on it. The molded wing is the ideal configuration but right now it requires way too much tooling time and the carbon rack can be ready very quickly. It will allow me to test and refine the system and then, if I feel it still has potential, I'll do the molded and sealed wing. Basically, the whole system is mounted on a fore and aft carbon tube so the rack+ ballast can be adjusted fore and aft as necessary. The ballast module( battery box below) will slide athwhartship as does the whole rack. Since the rack has no(very little) buoyancy(like the sealed wing does) the buoyancy pods on the end of the rack tubes will be a bit larger than the wing requires.

    Power Ballast System schematic:
     

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  8. Doug Lord
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    Doug Lord Flight Ready

    Trapwing

    Here is a great rendering done from one of the sketches above. It's not 100% accurate but does capture the essence of the "Turbo" High Performance version.
    Done by sailing kid:
     

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  9. Doug Lord
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    Doug Lord Flight Ready

    Trapwing 16 Turbo

    NOTE- the 16 is updated to 17.5 with an integrated rudder(appears doubleended). It will not be the first version-that is my 22 footer-under development now.
    ------------------------
    TENTATIVE TECHNICAL DETAILS 17.5' VERSION:
    originally posted in Design Challenge months ago; this version includes updates.

    LOA 17.5' with integrated rudder(appears double-ended)
    SA- 160 sq.ft. upwind 360 approx downwind if a spin is possible-definite spinnaker on wide version w/o foils
    12' sliding "trapwing" with 160 lb ballast
    All Up boat weight minus wing,wing ballast and keel ballast including rig:160lb
    75lb keel bulb
    130lb-180lb crew

    ----------------------------
    And once again ,in detail:
    LOA 17.5' using highly modified Blade or Falcon F16 hull(with integrated rudder) from Matt McDonald of Falcon,LLC in Port Canaveral, Fl.and:
    Hull weight(with cockpit) 73lb(actual weight+ cockppit mod)
    SA 160 sq. unstayed squaretop rig,carbon mast- 35lb
    Foils-17lb (foil assist approx 70% lift depending on crew weight)
    12' wing,all up-20lb
    movable ballast-160 lb
    motor,controls,battery (25lb est)

    ----------------------
    SUB Total=330lb (405lb for Turbo self-righting version with fixed 75lb ballast in bulb integrated with "foil assist"foils)
    crew=120-180lb
    TOTAL = 510lb
    ====================
    RM:
    160@ 9' =1440ft.lb
    20 @ 4' = 80ft.lb

    ------------------------------
    Total= 1520ft.lb

    HM@ 1lb/sq.ft. pressure = 1600 ft.lb.
    ------------------------------------
    This is with crew contributing virtually nothing to RM. A side seat option allows the crew to sit slightly outboard but still in a relatively fixed position-for ablebodied crew only and it adds RM.
    There is no guarantee that even after testing the skinny hull turbo version will be suitable for disabled sailors-only extensive testing will prove whether or not that is possible. IF that is possible it REQUIRES the selfrighting option.
    ==============
    This thing will trailer with the wing pivoted fore and aft and will require the same room a WETA tri does to launch rigged at a launch ramp. In Florida the boat would launch using a dolly like a cat does and that will make it easy. Keep in mind how heavy the 2.4 meter is and it is successfully launched in many areas. This boat is much lighter than that-maybe about the same as a Bongo-and about the same as a Hobie 16. Launching will be no problem with a dolly on a beach and if the ramp is wide enough the boat can be launched right off the trailer. The BOAT WILL NOT BE CARTOPABLE.
    The lead in the cart that slides athwhartship will be in approx. 20lb segments an will be REMOVABLE. There is no reason to sail with max ballast on a light day.
    A production version would have a reefable rig.
    This version will not be the first version which will be my 22 footer which is being worked on now. It will be done as soon as possible
     
    Last edited: Oct 17, 2009
  10. Doug Lord
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    Doug Lord Flight Ready

    Thanks to Rick Willoughby for doing this-very cool. You will have to click on "options" to enable macros.The spreadsheet moves the weight the distance you set in 1.5 seconds(for one cycle).The spreadsheet also incorporates a 20% grade-uphill(which the ballast would see infrequently). Rick has been a very big help-incredibly generous with his expertise!
    Moving 70kg(154lb) 5.49m:
    --in 4.5 seconds requires a 7.1 AH battery for well over* 8 hours of ballast movement equivalent to 5.49m(18') every 5 minutes.(1.83m in 1.5 seconds)
    --in 5.49 seconds requires a 5.8 AH battery for the same(1.5m in 1.5 seconds)
    *and I do mean well over....
    ------------
     

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  11. Doug Lord
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    Doug Lord Flight Ready

    Pterodatyl and on-deck movable ballast

    Thanks again to Julian Bethwaite for the comments and information posted here:
    -----------
    One of my inspirations -that has bolstered my own work on this project- is the Bethwaite/Billoch collaboration on the concept of Pterodactyl-which was conceived of to use on-deck movable ballast. Here is the original SA article: http://www.sailinganarchy.com/fringe...teradactyl.htm
    --------------
    What wasn't known then was what Julian says about it here. I asked him to comment on the Trapwing which he did in a PM that I'm publishing here with his permission. He reveals who was behind the Pterodactyl project:

    "A few years back these pages graced a thing called the Pterodactyl, it was a big double proa that Russel Coutts and Paul Cayard asked me to do as the ultimate circuit boat. Among other things its nice to see the OMR*go that route, but Russel was big on having 3 tonne of lead on tracks moving from side to side, inside the wing beams. I thought moving water through 200mm diameter pipes would be better, but the concept has merit. Your issue is that unless you have significant tip pods, then you will never be able to react quickly enough to keep the wings out of the water. Just cant do it! "

    *Ocean Multihull Rule: it is the predominant rating rule used in Asia (and
    Australia) it seems for handicap racing in this part of the world.(dl)

    Pictures of Pterodactyl:
     

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  12. Doug Lord
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    Doug Lord Flight Ready

    Trapwing-

    Here is another model that used the precursor to the Trapwing system:
     

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  13. Doug Lord
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    Doug Lord Flight Ready

    Trapwing: planing version

    One of the main themes of this design concept is that the resulting boat can be a self-righting keelboat. I was intrigued by the K1 concept( http://www.boatdesign.net/forums/sailboats/neat-singlehanded-keelboat-uk-30059.html ) where the designer chose a narrow waterline semi-circular section hull that was designed to be sailed heeled instead of flat like most planing hull dinghies. The Bongo is an example of a small keelboat with a planing hull. I've never really thought that was a good way to go because in order to plane the Bongo must be sailed flat which means that the keel bulb is not developing any RM. And while I like the K1 and the designers thinking I don't think it comes close to an easy to sail keelboat along the lines of a 2.4 meter. And no way are either the Bongo or the K1 "high performance".
    --
    The beauty of the Trapwing system seems to me to be that on a boat with a planing hull that has the power to plane in 10k or under it can be sailed flat upwind and downwind and can be designed to plane upwind and downwind.

    And high performance with a self-righting capability thanks to the design of the movable ballast wing and a bulb keel. Also, since the weight in/on the wing and the wing itself is moving to develop righting moment the crew is not taxed physically and can sail the boat with the ease of a 2.4 meter but with much more performance. I don't think there is a small keelboat anywhere that offers all this and that makes it extremely attractive to me.

    The advantages as I see them:
    1) easy to sail by almost any weight sailor.
    2) self-righting
    3) high performance-planing upwind and downwind
    4) variable wing ballast-moved manually or electrically
    5) two seating options-a.sit in and, b. side to side
    6) reefable rig
     
  14. tom28571
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    tom28571 Senior Member

    Doug,

    You are not getting a lot of interest so far.

    Ok, one big problem with any design that uses transverse movable ballast is that the righting moment decreases with increasing heeling. Not a good thing. A keel bulb, on the other hand, increases righting moment with more heel angle.
     
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  15. Doug Lord
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    Doug Lord Flight Ready

    ==================
    You're right, I guess-though a fair number of people have looked at some part of the thread. And I've enjoyed being able to put a lot of info in ,more or less, one place. I hope to add pictures of a prototype after the first of the year.

    I think the best way to look at this is a two person trapeze dinghy with the crew max out on trapeze and the boat sailed flat. While the crew cg will move inboard slightly with 20 degrees of heel, the cb of the hull moves to leeward actually increasing RM. After 20 degrees it might be time to reduce sail or feather the main.
    But there is one other thing adding to RM-and that's the keel bulb which increases RM with heel-though very slightly within the optimum heel range. This type of boat would be sailed like a planing dinghy-sailed flat or with a max 20 degrees angle of heel.

    I think it could be fun.....
     
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