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david r

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Posts posted by david r

  1. i wonder if there will be any components of this new rig that could be patented?  They say there will be special battens, and it looked like there was some sort of control arm at the head in one vid.

    Also why would a wide monohull with 2 keels be any more tippy than the average leaner sailboat?

  2. A production boat of a design that is made correctly should not fail out of the blue.  Pilot error or horrible conditions can cause a failure.

    Older boats tend to twist a little more and not be quite as fast as a fresh boat, but they should hold up fine.

    In the past the race was 4 days long on used and/ or new hobie 16s.  Done non stop in the 70's. Those days are long gone, but Cape Hatteras still has big storms.

    The stretched out version has legs where you can be done sailing by 2 or 3:00 in the afternoon.

  3. Thanks for responding.  I looks like ac type rules also are trickling into fleet racing if it's now ok to aim at the other boats as long as you don't get caught.

    I don't see why the blue boat did not just hold his course.  He had everything to loose with that dial up. The third boat (pavement) boat was only 37 seconds behind, and if they got passed by the third boat whilst doing a penalty turn, they would not win the series.

  4. About that super foiler finish of the last heat.  Which rules were they sailing under?  The blue boat had audio of "nice dial up", while the red one protested them for not holding their course.  Could be the refs had money on the blue boat, or they were using rules like the AC where you hunt the other guy.

     

  5. The cartoon shows a double surface main sail fitted to a mast that has shrouds and spreaders.

    i wonder if they plan to lay the boat on its side to install the mainsail. i think there are some patents involving double surfaced sails out there too.  They are a design problem in themselves, one problem being that they can weigh twice as much as a regular sail.

    i wonder if they have some breakthrough design for a giant double surfaced sail, or if they still need to figure out how the mainsail will look.  

     a 90' boat with a soft sail doing 50 knts. may a little bit wishful.

  6. 2 issues to write about.

    After looking at DL's videos of the model sailing, there is a problem. Either there is a hidden video that i didn't see, or there is no proof the the "model" foils with stability. There needs to be, in my opinion, at least 60 seconds of stable foiling on video to claim on a forum that the boat is a successful foiler. All i saw was potential; a creation that looked to have quite a bit of drag showing that it could possibly be a foiler with some tuning and driver learning. It is supposed to be a scale model, but the rig is an rc rig and prolly wouldn't work very well if scaled up. Also there is the claim that the foils are Pete Melvin inspired, but the tips are clearly pointing down after that reverse curve was added. The ac72 foils are well described as L/V. The L has a rounded corner and is less than 90 degrees, but if you lean an L over, the tip points up. I think the idea is to not lean the L as much on the light upwind legs so that it is just a regular daggerboard with a end plate. Z boards don't look like a Z, S boards don't look like an S, and L boards don't look exactly like an L. Which brings up the second subject.

    The GC32. As mentioned before Martin Fisher designed quite a machine there. The version 1 had the S board system that he designed for the A class. It seems like there were hopes that that system would fully foil, but it turned out to be a skimmer. GC32 Version 2 has L/V with T rudders. i think there was an interview were they said that the boards were nearly the same size as an ac 72 board. Boards from a boat over twice it's size. It foils really well, but they still use the reacher off the wind even in force 4 with a reefed main. Here is a helmet cam vid from the 2014 race in France showing that. There is text at the bottom saying the boat is trickle down from the AC, (6:40 aprox) so its a relevant vid, and i think pretty exciting.

  7. Trivia: Martin Fischer designed both the FP and GC32 foilers. I think most would agree he has done a commendable job.

     

    Melvin did the SL33 and Nacra20 foilers. Also the non-foiling AC45.

     

    Not sure who is in charge of the AC45 conversion. But the conversions may not be as robust a foiling solution as ground up foiling cats.

     

    Perhaps the foiling AC45 is a new build - or is it a retrofit?

    According to what i have read and seen on video, Fischer was on the design team for FP/Groupama C which were somehow concurrent projects. GC32 came later. Years earlier he designed an A cat that was supposed to fly, but 2 different builders were unable to get his design to really fly. It had down pointing boards and L rudders...i guess designers have since figured out how to get that to work.

    the ac45 design team from catsailing news:

    Michel Kermarec – appendages, general design

    Manolo Ruiz de Elvira – hull

    Dirk Kramers – general design, structures

    Joseph Ozanne/Mario Caponnetto – wing aero

    Scott Ferguson – wing structure

    Mike Drummond – general design input

     

    Melvin has a biz partner, Morelli, and he prolly deserves some credit as well.

     

    ps. maybe it was the 45's that required sailors to lift the windward board. The announcers talked about it i think.

  8. Those down pointing foils look to have less drag when not foiling and the As and that trimaran model from Perth seem to be very stable when flying. However the AC designers will prolly go for earliest take off speed with the foil type that the have been using...time will tell

    That rule they had about needing to lift the windward board was partly to make foiling more difficult. i wonder if they kept it in now that they plan to foil as much as possible ?

    In SFO they raced in sub-foiling and NZ seemed to have a lower take off speed.

    By the way, why wasn't that series winning heat that passed the time limit shortened? Generally at most races, if the race has had some wind from 1 general direction, the RC will shorten course to keep the proceedings within the time limit. It's only sensible since everyone has put in so much time and money to be there and get around the course, and to put results on the board.

  9. i suspect the 45s and 62s are going to have to race in sub-foiling conditions.

    Also getting a FP or nacra foiler off the beach and around the course on a blustery North Sea version of Texel would be a real feat. It wasn't that windy and the waves weren't that big last year from what i saw online.

    Wouldn't it be funny if the down tip boards used on the foiling A class turned out to be better for the all around conditions that AC and ACWS will be sailed in?

  10. DL, you did make an rc tri that looks like it could foil pretty well with some tuning of both the driver and the sail plan. So that is cool.
    from post 1307 on bd.net :

    hull length 5.5' 5.5x3.5=19.25
    mast 8.5' x3.5= 29.75
    total area mast, sail, jib 23.5'sq x3.5 82.25
    main foil 23.5" long area 39"sq. or 3.25'sq
    rudder foil 19" long area 29"sq.
    weight 21 lbs x3.5=73.5

    The chord length at top and bottom of the main isn't listed, and neither is the jib hoist or chord lengths head & foot. This 82.25'squared total area seems low for a 30' mast. My calculation was done by multiplying 3.5 times the listed numbers for your rc tri. How did you figure out the sail area?

    How did you measure wind speed and boat speed? There is more wind out on the water than on shore. Did you estimate?

    This whole scaling thing seems flawed; a 74#, 19' tri? good luck with that.


  11. Since you are showing this project;

    For review please list the relevant measurements of the rc tri. loa, mast height, boom length, overall weight, foil size-length and chord length, for our information. Also if you would please state what you think the sail area and area of the main foil is in inches squared or metric if you prefer. It seems like a pretty good size for an rc multihull.

    From what i saw, your rc tri is a real testament to the lifting ability of the central foil. You have all that extra weight and drag of the training wheels to a basic moth design, and it still lifted briefly. Granted you would need training wheels on a moth model since there is no one on board to balance the boat via hiking. I would be surprised if the world needed an 18'x 18' geriatric foiler that heeled to leeward however.

     

    That sail has a lot of power in a very narrow window and i suspect that helped lift the boat up. Mostly the main sail is just drag though, and i think that is why you are having a hard time tacking, and why you are overpowered so easily. Use a fucking normal looking sail. There is a reason that no full scale high performance rig has a gaff and all kinds of shape sewn into the upper part of the sail combined with a mast that doesn't seem to bend very much.

    thanks, if you do post that size information...

  12. The scaling of sailboats is rather complicated. It doesn't work to just scale everything by percent. But still yet,

    there is no way an 19'6" cat with 250'sq. sail area would be at all over powered in 8knots wind speed. Did you show your math any where?

    Those conditions were pretty smooth with light wind in most people's world, but everyone is entitled to their own version of reality.

    It would be pretty easy to make a sail in a few hours using good seam tape and some monofilm. you could prolly make 3 in a half day. I would think you could make a wing in styro , tape , and maybe a fiberglass tube or 2 pretty quickly as well. A styro wing would not turtle either, beside the obvious advantages in performance.

    Hope you get your AOI of the various foils dialed in soon. The ammas on their own are pretty useless in terms of providing buoyancy as i'm sure you are well aware.

  13. "drinking a cold one(diet coke,of course)"

    If you are serious about drinking that poison, then you should use this internet thing to check out aspartame.

    There is a very wide range of health problems caused by it. Everything from Parkinsons to the inability for women to conceive. They actually changed the name of aspartame as people are finding out it's an addictive neuro-toxin.

  14. This video is a find from somewhere on the www. It shows 2 very similar full foiling models that are up most of the time.

    Any speculation as to weather boards of this simple design would work on, say an 18' cat? The heave control seems to be very simple yet effective.

  15. First, i would never have the nerve to show an experimental build from conception-completion on the internet. After the fact internet display is stressful enough, so good job persevering.
    Question; are you using the word "we" in the editorial sense or is there a team on this project?
    Given the 90 pages on BD.net and 3.5 years build time;
    You should go ahead and make the mast top float now. You are obviously worried about capsize since you are avoiding sending the model out in any wind.
    You could shape down a piece of styro and cover it with sign vinyl or tape in about 15 minutes time. It is a pretty long lasting construction technique for how easy it is.
    Pretty much every home on the waterways of florida have seawalls of one type or another. Yours is a really nice rock one. Put a floating dock next to your existing dock and use it to store and launch some sort of water craft like a kayak, jon boat, small sailboat, or SUP. The exercise does a body good, and you could launch the model from home as well.

    Hope the model works as planned, or at least any problems are fixable, so that you can enjoy RC sailing it.
    criticisms : Huge sail plan made from material that is robust enough to use on an 18' boat. The top of the main looks too full as well.
    Doesn't look like an 18' version would be a very marketable product due to extreme build cost of making it trailerable, having 4 foils, keeping weight down, etc.
    i am skeptical about the change that you made to the NZ style L/V foil design. Th tip area is horizontal, not up, so even your name for it seems wrong.
    Hang in there.

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