The speed to weight ratio doesn't take into account wind speed though?? My home spot only gets 17-19kts max :(

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KA360 said..

KevinD002 said..


How does one measure this speed to weight ratio?

Your top speed in knots divided by your weight in kg
eg. I have done 37.35 knots and I weigh 64kg
so 37.35 divided by 64 =0.583

The higher the number the better your skill

The holy grail of speedsurfing would be a 1.0 - 1 knot for every 1kg

sailquik said..


BTW. I calculate my speed to weight ratio after Luderitz is now 0.623. Gautier is on 0.642!!!

So I would have to beat 39.8 knots to be a better sailor than you.

so so far I'm .44 got a way to go ! Still I haven't learn't to bear away properly yet or fine tune my gear..+ smallest gear is a waveboard.

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sboardcrazy said..

KA360 said..

KevinD002 said..


How does one measure this speed to weight ratio?

Your top speed in knots divided by your weight in kg
eg. I have done 37.35 knots and I weigh 64kg
so 37.35 divided by 64 =0.583

The higher the number the better your skill

The holy grail of speedsurfing would be a 1.0 - 1 knot for every 1kg

sailquik said..


BTW. I calculate my speed to weight ratio after Luderitz is now 0.623. Gautier is on 0.642!!!

So I would have to beat 39.8 knots to be a better sailor than you.

so so far I'm .44 got a way to go ! Still I haven't learn't to bear away properly yet or fine tune my gear..+ smallest gear is a waveboard.

I think you're all jumping the gun. Before you can justify it as a useful ratio you have to show, either empirically or theoretically that potential top speed is linear with mass. I thought I'd shown that leverage doesn't explain it, it in fact sends the ratio the other way. So it's more complex. Do you have graphs of top speeds of skillful, serious speedsailors that show it's a linear relationship? Maybe top speed divided by the sqrt of mass is better?

If it's linear, and the ratio of 0.623 is something to aim for, this athletic fellow should do 101 knots. www.nytimes.com/2008/01/09/sports/ncaabasketball/09asheville.html?_r=0

I suspect AA is right, there will be an optimum mass, any heavier and potential top speed will start to fall. The leverage vs. sail size disadvantage that large sailors have will take over. They just won't be able to hold up enough sail area.

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Ian K said..
The leverage vs. sail size disadvantage that large sailors have will take over. They just won't be able to hold up enough sail area.

If we looks at windsurfer design, there is fundamental simplify restricting this power to weight ratio.

If we simplify forces our forward forces , see it as connected levers
one is obvious.

forward force is proportional to weight of the sailor hanging down on the boom.

As long as nobody comes with radical design transferring this forces directly through hardware ( rig to the board directly) there will be minimal progress in top speed regardless of weight of the sailor.
I am guessing that radical change will suddenly increase top speed be 10 to 20 knots .

That still means 10 knots added to my result will be 30 + 10 = 40 but for top rider 53 + 10 = 63

That also relate to my previous comment that regardless of hardware capability there will be very little people able and willing to go with speed above 60 ktn.

If I could suggest a tip for board designers - first should be asymmetry. Top speed board should be at first optimized to go in one direction only on the course. That should give instant 5 ktn boost.

A bit more maths. The leverage a rider has on a boom goes up with the riders mass to the power of 4/3. (assuming all riders have the same BMI)
The leverage a sail has on the boom goes up with sail area to the power of 3/2 (assuming equal loading per square metre for all sails)
Then the maximum size sail a rider can use goes up with the power of 2/3 X 4/3 = 8/9. That's the point, if the sail size goes up with the rider mass to a power less than 1 lift will start to fall behind, and eventually overtake the other factors, that appear at this stage to favour heavier riders.

So using Sailquick at 75kg? as the reference, when he's on a 5.0 someone weighting 90kg should be on a 5.0 X (90/75)^8/9 = 5.9 sq metre sail
The 163 kg basketballer

www.nytimes.com/2008/01/09/sports/ncaabasketball/09asheville.html?_r=0

will be on a 5.0 X (163/75)^8/9 = 10.0 square metre sail

So even though the basket baller is 2.2 times heavier, he can only hold down double the sail size.
However, the cross sectional area of the basketballer has only gone up by 2.2 ^2/3 = 1.68. That's a significant saving in parasitic drag for double the sail power. So the relative saving on parasitic drag may possibly over-ride the relative loss of leverage for the larger sailors.

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Macroscien said..

Ian K said..
The leverage vs. sail size disadvantage that large sailors have will take over. They just won't be able to hold up enough sail area.

If we looks at windsurfer design, there is fundamental simplify restricting this power to weight ratio.

If we simplify forces our forward forces , see it as connected levers
one is obvious.

forward force is proportional to weight of the sailor hanging down on the boom.

As long as nobody comes with radical design transferring this forces directly through hardware ( rig to the board directly) there will be minimal progress in top speed regardless of weight of the sailor.
.

The only way to improve power to weight using the windsurfer configuration is to breed longer arms, or extend booms. But then you'd lose the instant control advantage windsurfers have. Other than that, I don't think there's much that can be done with the fundamental leverage limitations, apart from going the Sailrocket route.

Did you see the skipper of Sailrocket, Paul Larsen on TV last night, he's in the crew retracing Shackleton's voyage from Elephant Island to South Georgia. Part 2 next week. Don't miss it, he ranks the voyage above his speed record run.

............................... KNOTS.....................KG....................KNOTS/KG
Tom Chalko...................43.........................73 .........................0.59
Chris Lockwood............. 50.........................86.........................0.58
Izaac Perkins................ 38.........................65.........................0.58
Lucy Water................... 32.........................58.........................0.55
Craig Hollins ................ 43.........................80.........................0.54
Anthony Perkins............ 39.........................75.........................0.52
Ben Willemse................ 30.........................58.........................0.51
Tony Wynhoven............. 47.........................99.........................0.47

Hey I like that chart! At 0.57 it makes me look good! (and I'm only short too)

Maybe sailor height is not relevant since the load is going through their harness. What's the height difference of the harness hook between a tall sailor and a short one? Perhaps the advantage goes to those who have longer legs. I am only 5'10 but I am yet to meet someone 6'3 that has their hip bone higher than mine, I'm all legs! I don't use a nappy harness either so my hook on my waist harness is much higher than most and my boom is also above my eye height.

Why have a complicated formula. though? The aim of the game should be to have a competition that is more inclusive and allows people of all body types to get a victory somewhere. Speed sailing should develop some way of attracting the lighter sailors. Even if the heavyweights win most categories, and therefore the overall competition, the lightweights could have some place to gauge their own successes.

Anita, I'm impressed! Pound for pound, you're one top-notch sailor. Do you have long legs compared to your height by any chance?

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KA360 said..

Maybe sailor height is not relevant since the load is going through their harness. What's the height difference of the harness hook between a tall sailor and a short one? Perhaps the advantage goes to those who have longer legs. I am only 5'10 but I am yet to meet someone 6'3 that has their hip bone higher than mine, I'm all legs! I don't use a nappy harness either so my hook on my waist harness is much higher than most and my boom is also above my eye height.

Why have a complicated formula. though? The aim of the game should be to have a competition that is more inclusive and allows people of all body types to get a victory somewhere. Speed sailing should develop some way of attracting the lighter sailors. Even if the heavyweights win most categories, and therefore the overall competition, the lightweights could have some place to gauge their own successes.

Anita, I'm impressed! Pound for pound, you're one top-notch sailor. Do you have long legs compared to your height by any chance?

The height of the harness hook is not important, that's an internal force that all cancels out. It's the body stance relative to the sail that's important. Dinghys demonstrate that how the forces are arranged internally don't matter, whether it's a trapese line or a hiking plank, the righting moment is determined by the position of the weight outboard. That's also why waist or seat harness doesn't make any difference as long as they both allow a good stance. Use what's comfortable.

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Windxtasy said..

............................... KNOTS.....................KG....................KNOTS/KG
Tom Chalko...................43.........................73 .........................0.59
Chris Lockwood............. 50.........................86.........................0.58
Izaac Perkins................ 38.........................65.........................0.58
Lucy Water................... 32.........................58.........................0.55
Craig Hollins ................ 43.........................80.........................0.54
Anthony Perkins............ 39.........................75.........................0.52
Ben Willemse................ 30.........................58.........................0.51
Tony Wynhoven............. 47.........................99.........................0.47

Hey I like that chart! At 0.57 it makes me look good! (and I'm only short too)

Yes I was pretty impressed by your rating!

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Ian K said..

KA360 said..

Maybe sailor height is not relevant since the load is going through their harness. What's the height difference of the harness hook between a tall sailor and a short one? Perhaps the advantage goes to those who have longer legs. I am only 5'10 but I am yet to meet someone 6'3 that has their hip bone higher than mine, I'm all legs! I don't use a nappy harness either so my hook on my waist harness is much higher than most and my boom is also above my eye height.

Why have a complicated formula. though? The aim of the game should be to have a competition that is more inclusive and allows people of all body types to get a victory somewhere. Speed sailing should develop some way of attracting the lighter sailors. Even if the heavyweights win most categories, and therefore the overall competition, the lightweights could have some place to gauge their own successes.

Anita, I'm impressed! Pound for pound, you're one top-notch sailor. Do you have long legs compared to your height by any chance?

The height of the harness hook is not important, that's an internal force that all cancels out. It's the body stance relative to the sail that's important. Dinghys demonstrate that how the forces are arranged internally don't matter, whether it's a trapese line or a hiking plank, the righting moment is determined by the position of the weight outboard. That's also why waist or seat harness doesn't make any difference as long as they both allow a good stance. Use what's comfortable.

As a short lightweight I find my stance is right out low to the water whereas most of the heavy local guys stand pretty upright..

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Macroscien said..

I don't really understand what is wrong with you humans

I proposed something for our community for consideration that seems to be fun and bring additional valour to our windsurfing world.

If you don't like it , that is fine,

but this turned out to be spitting competition and you just seems to enjoying even more then main subject ( windsurfing )
chasing , barking and spitting on extraterrestrial creature (me).

If the same proposal come Kato or Brad you will be screaming in the joy of pleasure.

On every subject , on every neutral word I do say there is at least 2 red fingers.

If there is any place for next such competition ( Red Category) I am seems to be absolute SB champion.

Time for me really to get my f888g saucer and depart from SB....

DO NOT DRAG ME INTO THIS !!!

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KA360 said..

Maybe sailor height is not relevant since the load is going through their harness. What's the height difference of the harness hook between a tall sailor and a short one? Perhaps the advantage goes to those who have longer legs. I am only 5'10 but I am yet to meet someone 6'3 that has their hip bone higher than mine, I'm all legs! I don't use a nappy harness either so my hook on my waist harness is much higher than most and my boom is also above my eye height.

Why have a complicated formula. though? The aim of the game should be to have a competition that is more inclusive and allows people of all body types to get a victory somewhere. Speed sailing should develop some way of attracting the lighter sailors. Even if the heavyweights win most categories, and therefore the overall competition, the lightweights could have some place to gauge their own successes.

Anita, I'm impressed! Pound for pound, you're one top-notch sailor. Do you have long legs compared to your height by any chance?

Thanks! (but I'm not really a top notch sailor) I wouldn't call myself leggy but I do not have short legs. A bit longer than average perhaps.

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Ian K said..

A bit more maths. The leverage a rider has on a boom goes up with the riders mass to the power of 4/3. (assuming all riders have the same BMI)
The leverage a sail has on the boom goes up with sail area to the power of 3/2 (assuming equal loading per square metre for all sails)
Then the maximum size sail a rider can use goes up with the power of 2/3 X 4/3 = 8/9. That's the point, if the sail size goes up with the rider mass to a power less than 1 lift will start to fall behind, and eventually overtake the other factors, that appear at this stage to favour heavier riders.

So using Sailquik at 75kg? as the reference, when he's on a 5.0 someone weighting 90kg should be on a 5.0 X (90/75)^8/9 = 5.9 sq metre sail
The 163 kg basketballer

www.nytimes.com/2008/01/09/sports/ncaabasketball/09asheville.html?_r=0

will be on a 5.0 X (163/75)^8/9 = 10.0 square metre sail

So even though the basket baller is 2.2 times heavier, he can only hold down double the sail size.
However, the cross sectional area of the basketballer has only gone up by 2.2 ^2/3 = 1.68. That's a significant saving in parasitic drag for double the sail power. So the relative saving on parasitic drag may possibly over-ride the relative loss of leverage for the larger sailors.

I still can't follow the premise behind you calculations Ian, but the relativity you came up with has a lot of observed data to back it up.

EG: While I was doing my max speeds on my 5m sail ay Luderitz, the big guys were almost all using 5.8m sails to do their best speeds.

Can I suggest you take the other direction using scientific method. Look at the very well known observed facts among speed windsurfers (*Taller is faster, heavier is faster, Taller and heavier is much faster - all else being equal - or as close as we can tell to equal).

Take those very well made real world observations regarding size and speed and try to find the explanation for them. You seem to have started with a feasible explanation about body drag, but most speed sailors don't seem to think body drag is significant, or at least not very significant. Various devices and strategies have been tried to reduce body drag and, to my knowledge, no useful gains have been realized.

I have seen diagrams and force calculations in the hazy past that seemed to explain this* phenomenon, but I have no idea where to find them now.

AB stated somewhere that he thought, for his size, slightly smaller 5.6 - 5.4m sails would prove fastest in the ideal wind and water conditions. His explanation was that the drag would be less (Better lift to drag ratio). This also supports my observations that guys my size often do their best speeds on 4.4m to 4.6m sails when conditions are ideal. I came to the conclusion that a better lift to drag ratio (possibly combined with a lower center of lift - and so more 'efficient leverage') is responsible.

However, it is important to keep in mind that there are many conditions and competing factors that mean we cannot always get optimum efficiency in a given environment.
Eg. at Sandy Point on a classic WSW, one has to be able to survive sailing square to the wind and progressively onto a tight reach before one can get to the optimum angle for top speed. It is very difficult to control the optimum speed sized sail for the optimum angle on this tight angle run in without being lifted off the water or smashed! So we often have to run a smaller sail than what might otherwise be optimum, just to get into the course.

At Luderitz, I was using at least half a meter larger sail than I would be able to at Sandy Point in the same/similar wind because the start area there is in a bit of a wind shadow. You can handle the larger sail in the run in (and indeed need it just to get started) and only have to deal with the full force of the wind for a few moments as you round the bend on the bearaway. (Unbelievably exhilarating accelleration! )

The general principle of 'taller and heavier is faster' is so well observed though, that there is no question about it. It would be nice to have some good theories that attempt to explain this observation.

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Ian K said..

Did you see the skipper of Sailrocket, Paul Larsen on TV last night, he's in the crew retracing Shackleton's voyage from Elephant Island to South Georgia. Part 2 next week. Don't miss it, he ranks the voyage above his speed record run.

Of course he does! He has done the record. The next unfinished challenge is always the most exciting!

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KA360 said..

KevinD002 said..


How does one measure this speed to weight ratio?

Your top speed in knots divided by your weight in kg
eg. I have done 37.35 knots and I weigh 64kg
so 37.35 divided by 64 =0.583

The higher the number the better your skill

The holy grail of speedsurfing would be a 1.0 - 1 knot for every 1kg

sailquik said..


BTW. I calculate my speed to weight ratio after Luderitz is now 0.623. Gautier is on 0.642!!!

So I would have to beat 39.8 knots to be a better sailor than you.

The 'better sailor' is the one having the most fun!

I can tell you I really enjoy my sailing.

Enough to get me here anyhow (scroll down to the overall ranking): http://gpsteamchallenge.com.au/rankings/individual?country=1&year=&month=&state=&team=&age_division=&gender=

Sailing is reacting the force produced by the wind in a sail (or wing) against an interface such as water, land, ice or snow. When you lose contact with the interface you are no longer sailing, merely drifting in the wind.

The horsepower available to a windsurfer increases as the 3rd power of the wind speed. Maximum board speed is a function of the overall L/D ratio. The drag on the body of a windsurfer scales with the square of the apparent wind speed is a significant part of the total drag, whether the windsurfer knows it or not.

There are two additional constraints on maximum windsurfing speed, spinning out and catapulting.

When you spinout, the L/D on the water side rapidly approaches zero and you slow down.

Catapulting is resisted by the moment created by the weight and moment arm of the sailor (scales with height).

Bigger is better!

You can find my take on it here:

http://www.ayrs.org/Catalyst_N06_Oct_2001.pdf

Just two questions:
1. Do somebody know exactly what is optimal angle (in exact degree) : wind to the board course at that top peak moment at Luderitz ?
2. What was the wind speed at that time top 52+ records were achieved ?

Barney - extremely interesting article I need to read it few times to digest entirely but I love the spirit of innovation there. If that is still happening somewhere in the world? Have you got any link to the people forum specifically interested in new concept and designs ?
I could be much more productive to continue technical discussion for me in more specialized forum instead of dragging it on general .

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sailquik said..

Ian K said..

A bit more maths.

I still can't follow the premise behind you calculations Ian, but the relativity you came up with has a lot of observed data to back it up.

The premise isn't all that elaborate, just me getting let down by literary skills. But I'm up for the challenge of trying to explaining it with less maths.
Unfortunately you can't get away from physics. The leverage of the rider has to balance the leverage of the sail. Leverage equals force times the distance of action that the force is applied. As riders get heavier they also get taller, that's a win, win for rider leverage. As sails get larger the centre of lift acts higher up the mast. So that's a win, win for the sail as far as leverage over the rider goes. It however turns out to be a win, double win for the sail because we're basically comparing mass, which scales with dimension cubed against the power of the sail which scales with dimension squared.

When you juggle all those dimensions against each other you find the sail area that a rider can hold down is proportional to his mass to the power of 8/9.

But that assumes all riders and all sails are in the same proportions, for riders of the same weight taller wins. For sails of the same size, the one that's fuller up top will win the leverage game. So go for a tall guy on a sail that's full down low to beat this scaling game.

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Macroscien said..

Just two questions:
1. Do somebody know exactly what is optimal angle (in exact degree) : wind to the board course at that top peak moment at Luderitz ?
2. What was the wind speed at that time top 52+ records were achieved ?

Two very good and valid questions! Unfortunately, they are impossible to answer. The best we can do is make estimates and approximations from careful observations.

1. The angle of the wind varies continuously. It was changing in the gusts and lulls and varying over longer time periods as well. I spent quite a bit of time observing and trying to estimate by standing next to a flag near the 500m start line with lines drawn in the dirt. The canal angle on the best days varied between 130 and 140 degrees off the wind. The best runs were probably done at about 135 degrees OTW. On one day the wind was too broad for safety and this was the day people started crashing and a few people hurt themselves. That day I estimated the angle was around 145 degrees OTW.
It created a rolling chop about 30cm high going down the canal in trains. It also made waves in the finish area over 2ft high! I had a spin out half way down in the chop at top speed and crashed, luckily without injury. Others were not so lucky. The broad angle also made it very difficult to get good speeds and control. When you had a lull you lost speed quickly and it was hard to stay sheeted in. When the next gust hit you from behind it was really hard to use it. Mostly you had to sheet out to stop being pulled over the front. If you could get really good speed on the entry and build your apparent wind it helped, but there would always be a lull followed by a big gust somewhere down the run. For an hour or so the canal was pretty much empty until the wind swung a bit more east.
Some very fast runs were done by the Pros in the weeks after we left in sub 40 knots winds. The sailors reported that it was faster in those conditions when the wind was not quite so broad.

2. The wind speed was never constant either, and in fact is quite gusty at Luderitz compared with Sandy Point. I also spent a lot of time with my anemometer observing. Even on the best days the wind speed would vary up to and over 20 knots between lulls and gusts. You could be seeing 35-45 but then you would get lulls to below 30 and gusts over 50kts for a few seconds within a 30 second period. It was rare to get a run without a big lull or gust, often multiple lulls and gusts. I estimate that the best runs in my time there were done with the wind averaging about 40 knots, but with a range in most runs of over 20 knots variation.

There were anemometers mounted on the start and finish camera boxes and we could observe these in the start house. It would be interesting to know if the data was recorded. I didn't get the impression it was, but just watching the split screen with the two readings one could see there were often differences between them of up to 20 knots.

FWIW, the reported average wind strength at the time AB and AA were doing their record runs last year was just over 40 knots.

I found easy to follow new formula for Gybe Master competition.

Simply we could sail for half an hour - 30 minutes - count the amount of gybes made and total distance at this time.

So to calculate Gybe Master index we just multiply amount of gybes by distance made at the time. I think that tack or waterstart, or even beach start could count as well for simplicity or calculating turns

GM = Gybes x distance (in km)

For example in my yesterday sailing it will be approx

21 gybes x 8.68 km = 182.28

To calculate the best period I used GPS result and filtered 30 minutes period then counted manually gybes, Total Km are calculated by program .



For those of you willing to calculate and post their own GM index I will post this new topic GM competition.