atg

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About atg

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  1. atg

    DC Designs

    For a minute I thought you were going to say Clockwork came off the rack Alan! Please post less provocative titles! Karl
  2. atg

    Moth Developement

    Um, I think dismissing the full scale tow tank work of a naval architect as irrelevant is sort of bold? For the record, this was done with early Bladerider foils. He did similar testing with an M2 mainfoil later. And his hull was cut down quite a bit from a HT. Let's see, who are we going to believe - the guy with the tow tank who says lift is x and drag is y, or...wait a minute...there isn't any other real, measured data available! Hmmm. The relative contributions of spray drag, interference drag, and form and induced drag have likely not changed much. Foils have changed size, but fundamentally not much else. I would love to see someone take a newer boat and do the same tests. When they do, they will have something to compare it to. Hard to be much more relevant than that.
  3. atg

    Moth for sale

    Tempting, but it would just join my other project Moth on the downslope. We did finally get moved into the house after demoing the whole thing, so I'm that much closer to getting the router fired up on another head car mold for the flapless setup. Sorry if the full cambered foil section let you down! What sort of area and section thickness were you running? Really Clive seems to have the twin strut tailplane setup pseudo-dialed, so the smart development-minded foil builder would probably do that. Anyway the super skinny monolithic elliptical flapless anhedral mainfoil with the big span is lurking somewhere in Rhino awaiting a toolpath. Should be a winner. Would love to buy this hull and jam the system in, but I already have the tracks in the Prowler so that will continue to be the test platform. So much fun per dollar in this rig. Can't take money with you; trade it for some memories and scoop this Chris' boat up. I spent 12.5 for a Prowler in 2007 that was competitive for maybe a microsecond, and honestly it was some of the best money I ever spent on anything.
  4. atg

    DC Designs

    Probably want to upsize those wire blocks. I think 1.5" were the smallest ones that did not eat themselves. Bill Beaver lost his rig that way on Arrested Development at 1996 worlds. Julian Bethwaite came cruising through the dinghy park early in the regatta, had one look at his 1" wire blocks and said "Oh - that will never hold." Bill had done the math, and was sure it would hold. Sure enough, it didn't. No one came to get him after the rig failure, because a storm had wiped out the whole fleet, so he managed to restep the mast on the water with a bit of string on the end of the shroud, and got back that way. A size up is cheap insurance.
  5. atg

    Foiling Moth Setup

    Nige Oswald - Friday Harbor Chris Maas - some other island out there near Nige Andy Mills - Vancouver BC Dalton Bergan - what doesn't that guy sail? May have sold his boat awhile back though. There are some others.
  6. atg

    DC Designs

    Bummer dudes. Glad you are OK. It puts the old "journey not the destination" idea of boatbuilding to the test. I always figured I would send mine forward off the roof rack in a hard stop or accident, but somehow never did. And getting rear ended always seemed like a good possibility. Maybe LED bike flashers on the tack fitting? Sorry you missed the regatta. Nothing like long island sound in October. Who are the builders? Oliver? K
  7. atg

    DC Designs

    Probably best to not ask the question about RRS, but the short answer is there is nothing in the class requiring anyone to use it. The ICA does its own thing when push comes to shove. Steve made some racks that ran in the carriage rails on Anders' boat. I have no idea how much Anders sailed it. But the seat is one of the best things about the ride on an IC I think.
  8. atg

    DC Designs

    Sugar island is great but it is no place to go for a maiden sail. Trust me on this. Salt works well. My advice on awlgrip would be do the prep and pay someone to shoot it. Or roll test panels until you are happy. Or just prime it and declare victory for now. Big limber holes are the ticket when it comes to getting random items out of the hull (and not getting plugged up). I have only built one hull so I may not know what I am on about. Congrats on nearly being there. Karl
  9. atg

    DC Designs

    150? Is that Alice on yet another diet? Oh wait I think she was 93 or something. 150?
  10. atg

    DC Designs

    Camie 313 was the best hi-tack spray adhesive, but I think it is illegal now. 3m has similar stuff though. Hi-tack only-permanent. Art supply stores tend to have it. My rule of thumb is to grab the roof rack and push and pull vigorously with all my strength. If I cannot rock the entire car on its springs back and forth without the rack flexing then it is not strong enough to trust a boat to. In general, you need a very solid factory rail or hard bolt points in a structural channel. The only cars with this sort of factory rack tend to be German or Volvos (which are now Chinese apparently). Most japanese and American car racks are more for looks. Similarly, the type of Yakima that mounts with clips under the door weatherstripping is not solid enough. Finally, strap everything down with good line. Having a bit of stretch in the line is actually desirable. Wedge it until the rack deflects. Lighter laminate boats need a cradle. K
  11. atg

    DC Designs

    Well I stuck this into the other thread, but it seems more appropriate here: This may be the single best argument behind dropping the minimum weight. I have done a fair bit of solo cartopping with the 84-100+ kg boats and accessories. Raingutters are the bees knees, but probably not quite so important for the new lighter boats. One good trick I read somewhere (and used a lot) is the foam roller thing for singlehanded cartopping. I am surprised not to have seen anyone else doing it, though there are lots of those expensive Yakima roller things about. Find PVC pipe that will fit over the bars. Get some nice, dense latex foam - 1" will work. And a can of fast tack upholstery adhesive. Do this outside somewhere. Cut foam the same width as the pipe is long. Spray the pipe and the foam with adhesive and wait a few seconds for it to tack up. Put the pipe on the edge of the foam and start wrapping. Spray both surfaces as you go. Rasp off the butt end you started with to scarf it onto the wrap around end, tack the free end to the scarf, let it set up, then rasp off the remaining corner until it's perfectly round. Now find some sunbrella and tack that onto the foam. You will need to use your knees and put the pipe on the ground to make the foam bend. Now you can put the stern on the trolley, lift the bow, walk up next to the car, slide the roller over to your side, transfer the bow to the roller, then lift the stern and roll the boat forward onto the front rack. I have never tied the boat to anything other than the rack, as long as it is firmly attached to the rain gutters and tied down tight, nothing else is required for panic stops etc. especially with the new, light hulls. Tie the mast on next to it like Phil described. Be sure to copy the rig dimensions/hound height/spreader length slavishly from someone who is fast. K
  12. atg

    DC Designs

    So then why does a flat plate generate "lift"? Because in snipes it does (I know the answer, I'm just pointing out that this isn't quite accurate) Note also that Bernoulli's equations about "pressure" around a curved surface don't actually rely on "compressibility" A better way to think about it is that on the side the molecules are streaming past faster, fewer of them are engaged in browninan motion collissions with the surface in question. Thus they transfer less net horizontal vector energy to that surface compared to the molecules on the slower flow surface. And this net difference is the lift force. I think that's pretty much what he means by f=ma. The molecules hit the bottom, bounce off, and impart some kind of reactive force to the bottom of the wing that the top never sees. Sure feels like that when I put my hand out the car window anyway. I don't know if invoking Brownian motion adds anything to the concept; plain old vanilla motion would seem to do just fine as long as there is some flow.
  13. atg

    DC Designs

    Seems like we already know what is fast. Or Chris does anyway. But the pintail shape evolved when the boats were heavier. And were paddled. Which reminds me that one pretty direct way to figure out how much resistance a hull has (at least at low sucky speeds) is to paddle it. Maybe we should reinvoke paddling races to learn a little more about the subject? It's a lot more work than typing, but then most things are.
  14. atg

    DC Designs

    Seven degrees. I thought optimal planing angle was four degrees for a flat surface? I guess more would make sense for a less planar surface. I keep thinking a sharp corner at the knuckle is a mistake though, mostly because of what it does to the wetted surface when it touches the water at speed.
  15. atg

    DC Designs

    I was hoping this discussion might work its way around to something I understand a bit more! Foils? Poor craftsmanship? Count me in! It's only a matter of time before someone sticks one on the daggerboard also. There are certainly enough old hulls around. I still don't understand why the I14s put the foil so shallow unless there is an upward component to the flow there. Seems like that benefit would be less on a canoe.