Small Tri Test Platform

Discussion in 'Multihulls' started by P Flados, Sep 30, 2014.

  1. rcnesneg
    Joined: Sep 2013
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    rcnesneg Senior Member

    Any news?
  2. P Flados
    Joined: Oct 2010
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    Location: N Carolina

    P Flados Senior Member

    I should be out soon.

    I will have to dig the boat out from under some junk & figure out how it all goes together:)
  3. P Flados
    Joined: Oct 2010
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    Location: N Carolina

    P Flados Senior Member

    The first outing for the 2015 sailing season was pretty good in some ways, but less so in others. It was mostly light, but there were few periods of just enough wind to push the boat across the local park pond using the big sail.


    • I was able to remember how it went together
    • I did not really forget anything
    • No major breakages
    • I kept the mast non - horizontal


    • Durability is iffy (light weight construction plus wear & tear issues)
    • The boat is really not performing as well as hoped.
    • As the boat hooks up on a gust, the nose pushes down too much

    I was only able to get up to 9.1 kts and several items (beam bracket, mast) felt like they did not have as much margin as really needed.

    With a really efficient rig/sail, this layout would have some promise as a combination sail/paddle craft. The ama foils are very capable of providing "foil assist mode", allow easy roll control under load and the "kick up" feature really works.

    However, I am not sure how much more development effort I am going to put into this version. My sailing locations are two not so good choices. The park pond is sheltered, the wind is reduced and the wind is very shifty. Also, I only get short runs. Wrightsville beach sound side is better sailing, but there are lots of issues with things like tidal current, lots of shallows, power boat traffic, poor access.

    Since this was just a "crude test platform", there are lots of rough edges. In order to develop the boat much more, I would really need to sail at the beach in brisk air. However, each time I go out in brisk conditions, I worry that I will have a major failure at a really bad spot. The issues with tidal current and the poor access points make getting a crippled boat back home very uncertain.

    I am mulling over a "Small tri test platform - Version 2" that would re-use some of the parts. I may sail the current boat some more before deciding, but I am not sure.
  4. P Flados
    Joined: Oct 2010
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    Location: N Carolina

    P Flados Senior Member

    The small tri test platform project has restarted.

    First, some background of why and how.

    About 2 years ago I acquired a UFO foiling sailboat. The first summer involved more frustration than foiling. This summer I was able to keep it foiling on a beam reach for short intervals. The video below shows off my best day.

    At the current rate, it will take a couple of years of determined effort to become UFO competent. For me to learn, the boat needs a decent length of beam reach run on flat water that is 4.5 ft deep and winds that are 10 - 14 knots.

    I haver spent much time on many outings only to give up on all the closer sailing locations. The closest location has lousy boat ramp access that requires tacking up a long narrow channel to get to a "sailing location" and the "sailing location" has too many steep solid sandbars. I spent much time and numerous outings re-working the UFO rudder to be tolerant of minor groundings. My most recent outing to the closest location resulted in a hard grounding and broken mainfoil (not a cheap item).

    At about 50 minutes away, the Ft. Fisher basin gives me acceptable sailing, but only for a window of 3 to 4 hours at high tide. This location does have shallows and sandbars, but my risk of a hard grounding is acceptably low if I pay attention. Ft Fisher basin with tracks from the above video:


    In addition to frustrations over the depth requirement, there are the physical demands on me. Since I retired in January of 2019, I have been having symptoms adversely affecting my mobility and use of my hands. It is more an issue of joints and tendons than lack of muscular strength. I worry that these issue are going to get progressively worse .

    And then there is stamina. For a learner, the UFO is physically tough. When I am doing good, the hiking out wears on me but is not too terrible. But then there are the nosedives & pitchpolls that require a swim around to the bottom for getting it back upright. Even more frustrating are all to frequent "high speed dunkings" you get when the boat tries to roll over to windward (there are a bunch of these toward the end of the video). Most of the time you can recover after the boat slows down from dragging your torso for a while, but sometimes it will roll all of the way over into a capsize.

    I am hoping that I can assemble a "better old guy foiler" using a mix of parts. When I discontinued the small tri test platform effort, major shortcomings were sail, beam and foils. The UFO freestanding rig and sail looks to be a perfect upgrade for the sail. I have already constructed a heavy duty combination mast step and beam mount. I have one new UFO main foil and one repaired UFO main foil to use as canted out T foils. I think I will try using a dimension for main foil to hull centerline only a few inches more than the 27" used on the UFO. I am planning on having both foils easily retracted / extended using control lines.

    I am shooting for a big reduction in required depth (2.5 - 3 ft) with a kick up rudder needing about 1 ft more than the main foils. This will make Ft Fisher sailable at pretty much all tide conditions. Other locations also get drastically more friendly. I am hoping for a drastic reduction in dunkings and swims. For takeoff on a beam reach, only the leeward main foil will be down. The boat will be heeled to windward until it gets fast enough for the foil to support sufficient load to transition weight onto it. Main hull lift off will be more like flying a hull on a cat than the balancing act required for UFO liftoff. If the boat rolls to windward while foiling, the main hull will simply splash down with no drama. If the boat starts to heel to far to leeward, letting off on the sail will quickly let it settle back down (and if you go too far, again a simple main hull splash down). Foiling dead downwind is too unstable to even try on a UFO. Although it may not be fast, dead downwind foiling should work on this boat with both main foils down. Also, with both main foils down and flush with the bottom of the boat, "foil assist" at any downwind heading should work for those time when needed to get back onto shore.

    I put up the rig today and played around with checking out the general layout.



    Attached Files:

    Last edited: Oct 27, 2020
  5. Doug Halsey
    Joined: Feb 2007
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    Doug Halsey Senior Member

    I'm glad to see you're reviving your project & I certainly sympathize with the logistical & physical problems you're facing.

    I have a couple of thoughts about what might help you cope with shallow water:

    1-Ditch the aft T-foil & use a canard configuration instead.
    For pitch stability, an aft foil needs to be deeper than the deepest point of your main foils, making it the most likely spot to run aground. Further, it can't be allowed to kick up because the drag & the pitch of the hull would both be huge. Raising it vertically & sailing slowly in lowrider mode would work OK, but would greatly reduce your flying time.

    2-Use a planing surface instead of a foil for the forward member of the canard.
    This would totally eliminate any serious grounding damage for the pitch-control element. Planing surfaces have been proven historically - for example Sidd Shutt's small trimaran from the early 7o's:

    3-Mount the main foils forward of their pivot points.
    (For slanted foils or V-foils like my trimaran, this can be accomplished simply by using forward sweep, which has the added benefit of tending to suppress foil ventilation.)
    In this case, the lift component of the foil tends to cause the foils to rotate forward, and the drag component does the opposite. Mounting the foils far enough forward of the pivot point ensures that the forward rotation is the larger tendency in foiling conditions. Then, the brackets can be designed with limiters to totally prevent the forward rotations. And like a pop-up rudder, friction could be used to prevent the aft rotation while sailing, but to allow it when running aground.

    If you do these three things, I'm pretty confident you could have a foiler that would be fun to sail without having to worry too much with shallow water.
  6. P Flados
    Joined: Oct 2010
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    Location: N Carolina

    P Flados Senior Member

    Thanks for the suggestions Doug.

    When I first installed the kick up T rudder, I worried about the adverse affect of a kick up at speed. This was one feature that worked better than expected with my original testing. When it kicks up, the foil at the bottom rotates up to just below the water surface, stalls and churns. While sailing, I had it kick up several times at up to 8 or so knots with no problems at all. Until it gives me problems I will stick with it. I remeasured it today and found that I should be able to sail in as little as 2.5 ft of water if I keep my weight forward, less than 3 ft even with weight aft.

    Now for a "standard disclaimer" that goes with this effort. This is a intended to be much more of "test platform" than anything resembling a finished boat. Unless I find a configuration that I really like, I will not try to make a durable finished boat.

    I dream of creating a single handed boat worthy of an Everglades Challenge. This project could evolve into such a boat but for that I would probably build an entirely new hull with a plywood deck and a strip planked bottom surface separated by EPS foam.

    For the forward foils, I will start out with only one from my UFO. It is a complete assembly with a flapped T foil operated by a wand mounted on a gantry that is secured to the top of the main foil strut. I have two main foils and two wands, but currently only one strut and gantry. If the "physics" of the boat boat work out, I will implement UFO main foils on both sides, but may end up with shorter struts and shorter gantries. I have some ideas on making it able to kick up but again that may wait until things prove to be worth the effort.

    On the other side, I will probably start out with one of my original foil / float assemblies.

    The "main beam" will probably start out with a 8' 2x4 and a 6' section of 2x2. I will fab up a foil cassette / transition piece that slips the end of the beam. To start out with, the transition piece will be cheap plywood and cut up scrap wood. This is definitely an area where I expect that I may need play around with different configurations until I find one I like. This configuration lends itself to easy retraction on the windward side and easy extension to what ever depth is called for on the leeward side. After I figure out some geometry basics (fore/aft foil location, beam width and cant), the initial beam, foil mounts, float mounts will hopefully be made much less crude than what I start with.
  7. Samuel Langhorn
    Joined: May 2020
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    Location: California

    Samuel Langhorn New Member

    Hi Flados,

    any update on your design implementation?
    I am pretty much in the same boat :)
    age and intention, haha.

    I still have not seen any convincing example for a quick assembly/boatramp capable foiler.
    Like a mix between Trifoiler and Rave.
    Craig Tuffnel in NZ has something close, I would guess.

    Not sure how winters are in NC? should not be too bad so you can continue refining your project.

    Greetings from SF Bay
  8. P Flados
    Joined: Oct 2010
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    Location: N Carolina

    P Flados Senior Member

    Before It got too cold, I cobbled together a "rushed" assembly with one main foil and a single float on the opposite side. I did a "float test" trip to a local pond.

    The mast was too far forward (too much weight forward), and the boat rode lower than I wanted (as expected). I knew my floats were a little too low in volume and using the single float did not work out as well as I hoped for. After just a little bit of slow speed sailing, I capsized after a jibe (not unexpected) and did some minor damage during the righting effort. I said enough, limped back in, and packed it up. It was a good outing for "refreshing" my memory on how the boat behaves and confirming the need to address some items I was wanting to do.

    Since then, I decided to go ahead and remove the all of the deck surfaces and cut the boat in half at the midsection. I added 1 ft at the midsection (it is now a 12' boat) and did some general repairs and beefing up (apply fiberglass, add stiffeners) inside the hull to fix areas known to be too wimpy. My original glass on the bottom was a very thin layer and was compromised in a few locations. I patched the bad spots and then put another thin layer of glass on the entire bottom. I upgraded all the deck surfaces (fresh 1/4" ply) and made up a new mast step further back. I made a better structure for a first attempt at mounting the starboard main foil just behind my old cross beam. This will allow me use my old floats on both sides (two floats are essential for stationary and low speed stability).

    My most likely possible remaining project for the the winter is trying to come up with a better float (more volume) for one side to compare.

    I think I have a package "good enough" for another trip to the pond (primarily float test / low speed sailing) or to the basin (foiling possible, but more risk if the boat fails away from the launch point). However, I currently do not have a wetsuit and am probably better off just waiting till next spring.

  9. Samuel Langhorn
    Joined: May 2020
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    Location: California

    Samuel Langhorn New Member

    Sounds good :)

    Looking forward to seeing your next version of the experiment.

    I understand your attempt to be efficient and use an assymetrical configuration, but it should not be too much effort in making both sides the same. I guess you get a much better feel for the real behavior of the boat.

    For the floats I would simply shape some Styrofoam (including center 1/4" plywood stringer) and add a layer of glass.
    Same as surfboard making. That keeps you busy for a few weekends and you will have the floats you need for low speed stability. (just make sure to protect you against the styrofoam dust!).

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