How fast is a laser?

Discussion in 'Laser Talk' started by edchris, Jul 14, 2009.

  1. edchris

    edchris New Member

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    I have sailed larger boats, full displacement hulls, and have spent time in the Bombardier Byte, & some on Hobie Cats (16)
    I am now looking at buying a new Laser, or similiar boat, purely for fun, I don't envision racing it in organized events.
    I am curious as to the speed attainable on a standard Laser, with one 170 lb crew. Has anyone ever carried a GPS & obtained an honest speed readout?
    What speed wind is required to plane these hulls, & what speed would you consider the upper limit on a freshwater lake, ie no ocean swells to deal with.
    Thank you for the info.
     
  2. nesdog

    nesdog Member

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    From the Laser Performance Home Page:

    "One Laser sailor in Honalulu recently recorded the first Laser speed record at 16.8 knots, or 28 feet per second. "





     
  3. arm

    arm arm

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    my goodnes...and I am so darn slow, can barely point and suck at jibes...much to learn I have (sorry Yoda)
     
  4. Wavedancer

    Wavedancer Upside down? Staff Member

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    I love planing in my Laser (who doesn't?). As a lightweight (150 lbs), I can usually get my full-rig to plane (reaching) in winds of about 15 mph. Perhaps even at lower wind strengths. But in all honesty, the Laser is not a fast boat by today's standards; your Hobie 16 would be faster. And GPS recorded speeds are notoriously unreliable. For instance, there was a long discussion on Sailing Anarchy last year about a GPS equipped Albacore supposedly hitting something like 20 mph. Without getting into the nitty gritty of how velocity is measured by a GPS device, it is relevant to define whether we are talking about instantaneous speed (for instance, down a wave) or speed maintained over some (defined) distance. As an aside, 'official' speed records are done over a course that measures 500 m.
    http://www.sailing.org/26447.php

    The upper wind strengths for a Laser are in the 30-40 mph range. For instance, portions of the Boat Whisperer video (from Rooster Sailing) were done in 25-35 mph winds, and it certainly looks like that to me. But I would be reluctant to take my boat out under those conditions because (1) I prefer not to break things and (2) I would be swimming most of the time....
     
  5. WestCoast

    WestCoast New Member

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    16.8 knots seems awfully high to me.

    A 29er doesn't do much over 20kts, and a moth much over 25kts.

    I have always guessed (but never GPS verified) a top speed of around 12-14kts.

    Could be wrong, I guess on a 30+ knot day, with a big dude at the right angle you coudl do 16kts, but yeah, just seems rather high for our dear old Laser!
     
    • Optimistic Optimistic x 1
  6. josethpauline

    josethpauline New Member

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    wow! thats is so fast!
     
  7. Deimos

    Deimos Member

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    You can record quite amazing speeds using a GPS. Of course these speeds do not last long as they are not real but due to position fluctuations that are part of the GPS system. Which is why GPS's average speed over a period of time. So, it depends on how this speed was recorded under what conditions and for how long.

    Maybe an instantaneous speed down the back of a wave in a strong wind ? More info.

    Ian
     
  8. Kaiser

    Kaiser Member

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    So, records aside, does anyone have some general numbers?

    I've gotta believe that someone here has taken their GPS out and recorded speeds at various points of sail on a days with different wind levels.

    I'm not the original poster... just curious. For instance, close hauled on a 15kt day... is that 4 knots? 6? more? less?
     
  9. arm

    arm arm

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    hola.

    got it...the hull speed formula (theoretical) is 1.34 times the square root of the water line length...so, 1.34 times the square root of 12.5 gives 4.74 knots...that is that as long as you are a displacement hull...once you go on a wave, surfing...then off you go into fantasy land. Beyond that, is also beyond my brain reach because you would think that as long as you are on plane, the more wind the faster you go...until friction starts dragging you back down to auto destruct.

    happy weekend.

    Antolin
     
  10. Webmuppet

    Webmuppet New Member

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    I don't know how many of you will have seen the DVD, "Bass Straight Laser" featuring Michael Blackburn. There's some footage of him in the 'training' section of the DVD which is him sailing in some fairly monstrous seas - it's breathtakingly fast and almost looks as he has just hit the 'hyperspace' button. I would love to know how fast he is actually going......looks like there's a very thin line between exhilaration and outright terror !

    Nigel [​IMG]
     
  11. AJL

    AJL New Member

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    Well I had my GPS on board last Saturday and recorded 24.3 kts max speed. It was a nice sunny day about 28 deg C and about 26kts wind. Waves about 1m and I must have been doing well in front a decent wave at the time.
     
  12. glexpress

    glexpress Member

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    Are you sure your GPS was calibrated properly? I'm not trying to be a jerk, but anything on a Laser over 15 kts seems very difficult and anything over 20 kts seems impossible.

    Being a Detroiter and BYC member I've been very fortunate to be able to watch Bora Gulari train for his moth campaign out in front of our club. The man has spend thousands of hours sailing and perfecting his technique in the moth. He's broken the 30 kt barrier only a handful of times.

    Regular Moth sailors are shooting for 20 to 25 kts as top speeds. Hell I've had the Express 27 up to 18 kts and crewed on a Melges 24 that just got to 20 kts. Now getting a 18,000 lb 1969 Morgan 42 to 9 kts, that's impressive. :eek: I just don't see 20 kts being attainable in a Laser.
     
  13. mackconsult

    mackconsult Member

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    4.74 knots upwind??? I don't think that a laser reaches hull speed up wind. They are slow, but once you reach they can show there speed.
     
  14. Sean

    Sean Member

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    Most lasers sailors will hit hull speed of just under 5 knots like the other poster stated in a medium breeze upwind which is why you often see in a certain range of wind the fleet much more tightly condensed at the windward mark, often times with back markers within striking distance of the leaders.

    If the breeze is in a steady state with few shifts and an even velocity the leaders in a fleet have a lot less to work with and the sailors further down the fleet have less external inputs affecting them hence they make fewer mistakes. You can see then how most boats sit on the same speed upwind once everyone reaches max hull speed with little way to break thru that barrier.

    In lighter winds more skilled sailors will use the available wind energy more efficiently and as such maintain higher average speeds around the course compared to sailors further down the fleet who move around too much, have the sail set up in a less than optimal shape and steer in such a way that energy isn't converted into forward drive most efficiently.

    Conversely in heavy winds the opportunity now exists for skilled sailors to stay at hull speed upwind all the time except for brief moments when tacking or maybe navigating thru a tricky section of water, and they will exceed it on occasion thru steering technique and very powerful hiking which can enable the boat to surf or semi-plane for short periods, whereas further down the fleet this extra wind and wave energy becomes a hindrance and the boat and sailor will start to fight it as they deal with increased weather helm, water continually coming over bow, gusts that knock you sideways instead of driving you forward etc.

    That is why in a fleet of sailors of greatly varying abilities in heavier winds you will see such large gaps develop between groups of competitors. The ones at the front can utilise and get rid of wind energy more efficiently maintaining much higher averages around the course.

    I think for short periods of time a Laser can hit 20 knots such as going down the face of a wave. Who here hasn't sailed in 20+ knots and gone down a wave only to have the boom come swinging into the centreline with a completely unloaded sail. I think much beyond 20 knots is very rare as once you get to higher winds like around 30 knots even on a huge offshore wave the sail will stay out and always have some load on it.

    Overall I think a Laser will sit on close to hull speed upwind as soon as the wind is strong enough to get moving decently and in planing conditions 10+ knots beam reaching and close to that speed downwind are regularly achieved around a course.
     
  15. AJL

    AJL New Member

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    OK good point, I will re-check the GPS in my car. It has always been close to the car speedo in several vehicles but no harm in checking again.
     
  16. Kaiser

    Kaiser Member

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    Gps units don't need calibration. Someone earlier mentioned something about them being a bit flaky and easily tricked by surges in acceleration. i.e. I don't think the max speed is reliable.

    If there is an average speed that you can reset and watch over the course of a couple minutes that would seem like a more reliable number
     
  17. Beachcomber

    Beachcomber Member

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    Here's H2O Joe's blog entry on this unofficial, unrigorous flat water Laser speed record.

    16.8 knots

    http://horsesmouth.typepad.com/hm/2009/01/a-dispatch-from.html

    Michael Blackburn averaged 8.6 knots in his Bass Straight crossing and had an instantaneous reading of 19.7 knots on a big wave.

    http://www.shortypen.com/brdboat/cruise/blkburn/

    As others have pointed out, a GPS unit does not need to be calibrated, but instantaneous readings are unlikely to be very accurate. A few companies are making relatively low cost GPS's integrated with an IMU (inertial measurement unit). These are a lot more accurate for speeds and accelerations, since both units correct each other. One of those would be good enough for a casual record like this, but for something more rigorous, there has to be a minimum time or distance over which the speed was maintained.
     
  18. ChalmersP

    ChalmersP Member

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    Anyone know how fast a 420 goes? How about a OD14?
     
  19. GeoffS

    GeoffS Member

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    Here's some information on getting good speed numbers from GPS data:
    http://idniyra.org/articles/IceboatSailingPerformance.html
    Bob Dill knows a thing or two about speed measurement as the past world sailing land-speed record holder (116.7 mph in 1999, which stood until last spring).

    The technical details in the article are a little dated (and I think Bob has written something more recent, but I can't find it), but the basic principle of eliminating outlier points by looking at the data over time is absolutely applicable.
     
  20. tcraig812

    tcraig812 Member

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    3.21sail.PNG My Snark Sunflower topped out at 4.5 mph today 3/21/13 on 15 mph gusts. Any more wind and the mast will probable bend.
     

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