Dave Clark

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About Dave Clark

  • Rank
    Anarchist

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  • Website URL
    http://fulcrumspeedworks.com/

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  • Location
    Rhode Island
  • Interests
    UFO, International Canoe, C-Class

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  1. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    We have another installement of our "Show, don't tell" series. It took a lot of effort to stop myself from announcing this one throughout like a horse race. DRC
  2. Dave Clark

    HPDO- Why cancelled?

    For me personally, being in the dead center of the annapolos boat show weekend made it 100% impossible to attend with team UFO. That's what I know from my own experience. DRC
  3. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    That's one of the old setups. Some cunningham before rig tension. Then rig tension, then WAY WAY WAY more outhaul. Flat N twisted achieved DRC
  4. Dave Clark

    C-Class Little Cup news

    It appears to have got windier on the course later. Observe Aethon the Angry Bird doing a very pleasing if burp-heavy low foiling pass in what looks like a reach (10 or 12 knots of breeze??) Re the drag off the stern, at least my hunch is that Aethon needs bigger rudders and mainly gets foil assist and light foiling done while dragging the stern a little. That's my take from sailing it. The two are quite hard to harmonize and if often stalls in takeoff. The mainfoils even with 30 inch section removed are very high area vs the rudders (about four credit cards of area between them). Still goes fast but the exit off the stern isn't operating entirely as designed in this configuration. I will say (didn't make it I had UFO duties) Dad and trev didn't seem to want for boatspeed, so it's not like any critique is warraned. DRC
  5. Dave Clark

    C-Class Little Cup news

    I don't see you fielding a boat either. Got a wee bit of match match racing firing up in the start of race 2. Looks like 5 knots of breeze on the course. Huge thanks to Marc, Trev and Breck for collecting media from this event for those of us who can't make it. DRC
  6. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    The top comment from passing testers in the first year was "this pinboard sucks". Basically if you're putting it through in very calm water it's fine, but if the boat is bouncing at all (imagine being 12 and trying to do it), it's a hellride. That and the improved righting handles were massive upgrades to the creature comfort factor of the boat. We saved just enough money in consumables in the BOM over the leadup to make those upgrades cost-neutral for the product. The second most common comment was "these hiking straps aren't comfy" but to be honest, having tried ten different iterations of hiking strap, they are the best you can get, without question. You can have initial comfort or you can be secure in the boat when foiling but not both. In the great news category, I sailed #73 for about three hours yesterday in nasty swells and about 18 knots of wind with my old sloppy untightened gates and worn teeth held closed by the new velcro strap. The foil never budged. Issue finally resolved. DRC
  7. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    Same format as previously Main foil trunk - I respect what you say, yet it's hard to tell whether my #4 is within your expectations of slop. Any rule of thumb? PM /email me if easier. If I am all OCD and add velcro, felt or carpet, any significant drawbacks? It's never going to hurt to recast or shim the trunk to tighten it. Realistically, though, a good amount of your slop is up at the board head, where arguably 8 wraps with electrical tape would arrest lateral wobble Rudder lifting - gotcha. I might copy a trick I know, tying a thick bungee that adds friction between gudgeon and foil -- though it makes it harder to hoist, so blah. Tis but the work of a 1/4 20 tap to add the threaded brake which is a lot less draggy and cumbersome. Length of dyneema jumper lines - ok, I do have a loos gauge, does that work? If not... what? What range of tensions should I be able to achieve, and how do you test it (with sail on and cunningham at X, without sail...) ? See post 1532. All data established with a spinlock rigsense. $100 of greater clarity in all things rope. I don't schill gear, but that's a genuinely good tool. DRC
  8. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    Questions in italics, answers in normal text Main foil trunk seems loose -- the main foil, fully down and locked... moves, wobbles and shifts, specially when in displacement mode. Is this normal? The other foilers I know have a tight-ish profile at the exit point (bottom). These tight exit profiles do have some gap or flex to handle different rakes, but still hold it well in place. I'm tempted to put 3M velcro (hook/loop side) tape in there to shrink it so it 'grabs' a bit... I've experimented with felt linings with no good results. As a daily user of the boat I've found little reason to date to eliminate minor clunking around. Major slop is detectible in sudden shifts in flightpath but I've never traced that to a sloppy trunk. In that case it was a loose nut in the hand wheel guiding the rudder, an affliciction I call "the jumpies". Note that, given that I use the boat at least twice a week and keep my demo boat turnover to a minumum (we've been running #73 very hard since January) I'd be the most motivated and equipped to fix something if I found it an impediment to making sure the boat presents its best possible performance during all demos. So I'm actually already making a pretty serious bet that this really is more "feature" than "problem". Progressively increasing side to side slop in the rudder gudgeon is, I think a bigger issue, and I have an upcoming reverse compatible fix for that. Main foil - lifting it. Any tricks/rigs to make lifting the main foil easier? - say, for an 8yo. I'm mulling having a pulley/shockblock tied to the spreaders right against the mast (for minimal/no leverage against the spreaders themselves). The foils are heavy. A neat block and tackle system on the mast for little kids would probably be the most obvious and sensible addition of creature comfort. Rudder - lifting it. Any tricks? No ideas here... let off the rudder downhaul before you get into your landing zone and allow the foil lift to lift it up. Cleat it at half depth and proceed towards your ramp or dock. In later boats we added a nylon thumbscrew on the side of the rudderhead to act as a "brake" this when screwed in stops the rudder from falling back down due to gravity if you stop and thus decrease the hydrodynamic lift on the rudder. Loops for bow bridle. In some conditions, a line around the mast works great. In others, I wish there were loops like we have for the beach wheels. Would it be safe to drill through the joiner lip? (name?). This would work with some form of clip on bridle, that is clear forward of the crane/wand setup. Yes. I made one brief concession to cosmetics and left handles on the bow out of the hardware layout. Be sure to seal the inside of the holes How do you walk it around on its wheels? Holding it from the bows or stern breaks my back. The bridle mentioned above might also be useful to walk the boat around with the right fore-aft balance. One hand on the foredeck. One hand on the mast or mainfoil. Forward arm/crane moves a bit port/stbd. Say, 15-20 deg. Is this normal? We may have knocked it a bit around. Comprehensively normal. Is there a standard length to the dyneema jumper / diamond lines? We had a minor accident where one untied from its bottom sheave, and re-tying it ended up shorter, so we shortened the "good" one... before taking a measurement. So we're now a bit off in standard settings. Also, what's the right thickness? There are so many loose tolerances in that system that approaching any part of it with a tape measure is the wrong approach. A strain gauge gives you meaningful numbers. Mainsheet line - what's the best mainsheet line? I am thinking of 4mm something light and grippy... @Dave Clark - your "best settings for light air" post is excellent, couple of quick questions from there: - 15 turns on the batten... from whhat baseline? also, do you tighten after you hoist, or before? The battens come from north with nearly zero tension on them. One must initially turn them in until the "speed wrinkes" are gone. After that point you have a "loose batten" baseline. That's where you add from. Bear in mind that these are 180 degree wrist turns, not 360 degree revolutions. - say a boat is tuned just right with those setting, how do you depower from there? Ease Shrouds. ADD CUNNINGHAM AND OUTHAUL DRC
  9. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    Ten feet is 305 cm. All I know is I called, gave the dimensions and asked and the people in customer service repeatedly "are you sure? I will be bringing this to logan airport with the expectation of bringing it on my trip" to which they replied "yes, we're sure", repeatedly. But sure, maybe you're right anyway. DRC
  10. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    UNBELIEVABLE NEWS ALERT: After a little research, it turns out you can check a UFO as baggage on a flight across the Atlantic with Virgin Atlantic for $100 (Boston to London). That's the cheapest shipping of all time! If you're in Europe, reach out to us to fly over, demo the boat and fly back with it. That's right. You get one checked back for free so all you need to pay is the $100 oversized bag fee. I'm amazed! Time to book some regatta dates for myself in Europe. DRC
  11. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    It seems a good deal easier to me. One of the critical drivers of tough tacking is the reversed relationship between the center of effort on the sail and the mainfoil. On a conventional dinghy, the center of effort on the mainsail is slightly forward of the daggerboard, so pumping the main will pull you out of irons and in a normal tack, once the sail catches on the new side, the tack is nearing its successful close. The opposite applies on the UFO, so you need to be very careful to keep the mainsail very far out during tacks before it wearther-vanes backwards around the mainfoil. Keeping the foil up does help a bit. There are other forces in play as well, but this would help in close quarters. DRC
  12. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    And here's how you do it in really light stuff. It's sort of a pirouette. The trick in the really light stuff is to pop the bows out during the turn and then stomp them back down to lock the new heading. Essentially the addition of that much ultra low aspect sideforce helps it maintain heading and build speed at super low speeds. DRC
  13. Dave Clark

    Steve and Dave Clarks Unidentified Foiling Object

    It's made of PTex. The material that surfaces the bottom of skis. As with most things, we try to be a customer as little as possible, so it's made in house with an interlocking holesaw head on a drill press. DRC
  14. Dave Clark

    Cheap dollies

    I sailed vectors competitively for a couple years. Don't shoot yourself in the foot with an iffy dolly. The boats are genuinely tippy and need to be tied down to the dolly. They also aren't intensely light, so wheel bearings do matter. To be honest, the only cheap dollies are the ones you build yourself, which is why we now build our dollies in house at Fulcrum. If you can find a pair of scrapped carbon sweep oars from a highschool rowing team those make for a great starting point for home built composite dollies. The best dolly I've built to date is made from an oar, glass and foam. Weighs about six pounds and is stiff as a board. DRC
  15. Dave Clark

    What is it?

    Been down it on a boat with similar dimensions. Also one with a shroud base that makes sense, sufficient displacement and a wake coming off the stern. I think the photoshop comment must be valid. The boat in these pictures was originally a three-point configuration z-foil boat in the vein of brett burvilles early foiling moth, but Dad got bored with that part at a point and decided to take the foils off of it and make it the world's most ferocious boat stabilizing trainer. It fulfilled that design brief in spades, teaching me never to take stability for granted ever again. The overwhelmingly dominant issue is the outright absence of any innate roll stability. When you build a moth, you get away with it because the sailor is so much more massive than the boat that a couple steps one way or another on the tramps is enough to actively stabilize the boat in displacement mode when not hiking. When you make it heavier, your ability to keep it level with small motions goes down. At about double the weight what was a light step becomes a hard stomp. Less skilled users have to bodyslam it back and forth. Once you get to triple the weight (about like the locust above and probably the rowing shell further up as well) your manpowered control regime doesn't entirely cover all the types of roll the boat can exhibit. In motion with wind on the sail it's fine, so long as the wind is fully consistent. Getting going is a real hassle. Most of this is about weight in the rig which is a big heavy moment arm that you'll need to fight constantly. Boats like this tend to be a really informative design lesson in 1) the importance of all the other states not covered in the basic RM calculating free-body diagram and 2) the full capacity/limitations of the human sailor on the boat in making all those other states work. You're not looking at easy sailing. DRC