Kite, 49er, Moth: who's the fastest of them all(around a course)?

Discussion in 'Sailboats' started by Doug Lord, Dec 3, 2010.

  1. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

  2. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    From Patrick on SA-the guy that organized this event:

    Posted Today, 12:44 PM ,post 119(follow link in first post)

    Kiters are on 13 meter Cabrinha Crossbows

    so certainly a sail area advantage...



    Moth
    SA-86sq.ft/ 8sq.m
    Sailing Weight- 241lb(est crew at 175)
    W/SA=2.8
    =========
    Kite
    SA- 140sq.ft/ 13sq. m (1.63 times Moth sail area!)
    Sailing weight(est kit + board 20lb,est crew 175)= 195lb.
    W/SA=1.39(!!!)

    =========
    49er(nevermind)
     
  3. RHough
    Joined: Nov 2005
    Posts: 1,792
    Likes: 61, Points: 0, Legacy Rep: 793
    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    Is anyone surprised by the results?

    Comment at the end of the video was "If I wanted to sail a boat, I'd sail a Moth for sure..."

    On another day in other conditions the results would be different.

    Former ISAF President Paul Henderson has suggested that Kites and a new multi-hull be included in the Olympics.

    Progress is wonderful!

    R
     
  4. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    =====================
    I agree! But I was a bit surprised how close the Moth was-even more so after finding the kite SA. Looking at the SA of a kite really sheds some light on their speed potential-as does the recent "Trophee St. Clair" in France where foiling kite boards apparently dominated the racing.
    Good things,exciting things to come.....
     
  5. cardsinplay
    Joined: Oct 2010
    Posts: 330
    Likes: 3, Points: 0, Legacy Rep: -74
    Location: Camp Plasma

    cardsinplay da Vinci Group


    To be fair and probably more poignant in light of the need to grow the sport on all levels, Randy, the young lady present for the interview component was asked which craft she would want, given a chance and she quickly said... "The Kite"

    That is where new blood in the sport is going to gravitate. Kites are way less expensive, easier to transport, faster on the water, easier to learn and incredibly versatile as an all-around, multi-season sport. Having video clips like this one up all over the Web will quickly jack kite gear sales.

    Next up here in Utah.... we're putting a foiling Moth up against a kite in the backcountry terrain of Alta Ski Resort to see which one can handle uphill sailing the best. Then we'll fly the whole show to Maui and see how the Moth does in the overhead, reef break stuff at Jaws. I'm pulling for the Moth, but it doesn't look good... and for the whiners, we'll reduce the kite's rig size to 8m to end that bit of girlishness.
     
  6. RHough
    Joined: Nov 2005
    Posts: 1,792
    Likes: 61, Points: 0, Legacy Rep: 793
    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    It just the basics. SCP/Weight, the Moth SHOULD be faster than a 49er.

    Did you miss the point? The kite won because the design is better. It carried more sail area and sailed higher and faster. Simply adding area to the moth would not improve the L/D. If the kite had just had better VMG by sailing faster at a lower angle it might leave room for doubt, faster AND higher is game over.

    The proof if anyone wants to look is that a draggy boat like a foiling Moth is dead slow in 40+ compared to a kite. Foiling kiteboards might prove faster in moderate conditions but just like the Moths, when the wind comes up their inability to carry sail will hurt them. Simple geometry, the ability to carry sail is related to heeling moment. Increase the heeling arm by flying on foils and you limit the area the sailor can handle.

    R
     
  7. Timothy
    Joined: Oct 2004
    Posts: 307
    Likes: 15, Points: 18, Legacy Rep: 202
    Location: canada

    Timothy Senior Member

    It may be because of the relative skill levels of the sailors or differences in the quality of the euipment but at my club in Thailand there is no way that the kites can sail as fast or point as high as the formula windsurfers. I have noticed that the kites can now plain in lighter winds and that their pointing ability has improved, a good thing as a few years ago it was not uncommon for the kiters to be stranded, unable to return, if the wind tuned offshore Still there are times in light on shore winds when windsurfers have no problem sailing off the beach and the kiters are powered out by the clubs dingy. No argument that kites are the future. They are cheaper, no doubt faster in a ditch, and a novice can be plaining in three days, while on average it takes about four months of constant practice to be able to plain on a windsurfer. And of course there is the acrobatic stuff. I suspect that the kiters ability to shunt instantly as apposed to the insanely difficult power jibes the windsurfers must preform could give the kiters an advantage on a short course but not on a long one.
     
  8. Cheesy
    Joined: Aug 2008
    Posts: 315
    Likes: 12, Points: 0, Legacy Rep: 189
    Location: NZ

    Cheesy Senior Member

    Two things Doug, a kite board is much lighter than that and secondly 13m is the flat area of the kite, the projected area will be significantly less, think of the lift vector with a curved foil on a cat
     
  9. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ==============
    I was guessing at the kite board and kite weight because not one person in the SA thread posted it-you got better numbers?
    As to "sail area" "normal" sails are measure with the actual area-since a kite is a sail it probably shoud be measured the same way,don't you think?
     
  10. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    --------------------
    The 49er has an SCP/Total weight of 44%; the Moth 48%. Pretty close. I think W/SA reflects the difference more accurately. 2.8 for the Moth and 1.39 for the Kite(or better) Better=smaller #.
    I don't see why a souped up moth with variable area foils(or different foil sets for the conditions) couldn't be much faster and capable of sailing in 40+ with
    more RM and a smaller sail. I don't think the final chapter has been written yet in foils vs planing kite boards but the kites are improving dramatically all the time and there doesn't seem to be much 'outside the class rules' experimentation in the Moth as yet.
     
  11. RHough
    Joined: Nov 2005
    Posts: 1,792
    Likes: 61, Points: 0, Legacy Rep: 793
    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    At high wind speeds sail area is limited. So at some wind speed the Moth will have to reduce sail also. For the speed guys, I'd have thought that larger and smaller rigs would have been tried on a known good platform to see if they could get closer to 40 knots.

    The 49ers have stalled in the mid 20's, Moths have stalled in the mid 30's, Kites are in the mid 50's.

    Even the guys that sail two or more of the boats are shocked at the rate of kite development. Noted as absent from the sail-off: a Formula Sailboard and a twin trap multi (Tornado or C-Class).

    The "race" didn't really prove anything except that on that day in those conditions a kite was fastest. Below some wind speed the 49er would win, above some wind speed the Moth would be the loser.

    How about a Wing Moth, a Wing A-Class Cat, and a Kite over a course longer than .3nm?

    To get "your" boat to win all you have to do is pick the right conditions.

    R
     
  12. cardsinplay
    Joined: Oct 2010
    Posts: 330
    Likes: 3, Points: 0, Legacy Rep: -74
    Location: Camp Plasma

    cardsinplay da Vinci Group


    Really, that's all you have to do?
     
  13. Cheesy
    Joined: Aug 2008
    Posts: 315
    Likes: 12, Points: 0, Legacy Rep: 189
    Location: NZ

    Cheesy Senior Member

    If you are using the kite area for some kind or rating or handicap system sure. However I was under the impression that you were looking at this from a more scientific view point (predictive ratios etc) in which case the projected area would be more appropriate, in fact dont most sail/wing measurement rules specifically not include horizontal surfaces? which is what the tips of the kite are. All of the above is largely irrelevant though due to the wind speed gradient off the water, the kite will be in significantly higher velocity wind, which brings up a third point; to compare such craft should the kite rider be allowed to loop the kite off the wind and zig zag the kite up and down on the wind (there is probably a term for this as well), both generating significant lift through the artificially generated apparent wind.
     
  14. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    I find it intriguing that the Moth can develop almost 1000ft.lb. of RM(with a 175lb. crew) and uses an 86 sq.ft sail when the max RM for a kite guy@175lb
    is about 595ft. lb. with a 140sq.ft. sail.
    Must be like what you're suggesting Cheesy and/or the high degree of vertical lift(not acting as HM?) from the kite and/or the kite angle. What say you, Randy? Very interesting.
     

  15. Cheesy
    Joined: Aug 2008
    Posts: 315
    Likes: 12, Points: 0, Legacy Rep: 189
    Location: NZ

    Cheesy Senior Member

    How exactly are you working out the kite RM? You have to remember that the centre of effort of the kite is likely less than 1m from the water surface and the direction of this vector can be controlled (to a much bigger degree than a moth), the RM is not the limiting factor. Again comparing the kite area to a moth (or most surface craft) is irrelevant, it is flying in much higher wind velocities. With regard to the video, they could probably carry that kite to over 20kts wind speed before dropping size, it would have been closer to the lower limit of that kite than the higher...
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.