body weight vs. sail size vs. speed

body weight vs. sail size vs. speed

Post by Jay Run » Wed, 20 Sep 1995 04:00:00


Quote:
> Is there a way to determine the
> theoretically equivalent sail size for us in the same wind conditions?

My rule of thumb - 60 pounds = 1 meter

This is very rough because it leaves out all the other factors - board size,
fin size, sail type, skill level, and sailor preference.  Racers 40 lbs less
than me rig the same sail, sail straight upwind and downwind.  I reach back
and forth looking for bumps to jump/crash.
My observations have found that this rule works pretty well.

Jay

 
 
 

body weight vs. sail size vs. speed

Post by Jack Fall » Wed, 20 Sep 1995 04:00:00


: Please help my buddy and me end a longstanding debate. I am 5-7 and 143
: lbs. He is 6-4 and 180 lbs. Is there a way to determine the
: theoretically equivalent sail size for us in the same wind conditions?
: Assumptions:
: 1. We both have the same sailing ability.
: 2. We have equivalent  boards - he rides an Astro Rock when I have my
: E-Rock.
: 3 We both have modern 1994 cambered slalom sails, his are Windwing,
: mine are Hot.
:
: Empirical Conclusions:
: 1. He seems comfortable with a 6.7 m when Im with a 5.0 m sail.
: 2. He is always faster than me when we're both fully powered up. In
: light air,  I am faster do to being more powered up than he.
:
: Is it just as simple as his weight and moment arm allow him to carry a
: proportianetly higher sail size or is something else going on?  Is
: there a complete theory on this??
: Much thanks.  As I am the better sailor in most other regards, this is
: driving me crazy!!
:

At marginal planing conditions the light sailor will come out ahead since he
can plane earlier, stay on a plane longer and head up higher while still
planing.

In high wind the heavyweight can hold down more sail and thus is likely to
be faster.

I would guess at 25 lbs = 0.5 m2.  Hence 37 lbs would suggest about 0.7 m2
difference.  This suggests to me that you could probably handle a bigger
sail.  perhaps a 5.7 or 6.0 with more downhaul to avoid overpowering in
gusts might help you keep up with him.

--
Jack Faller
Deparment of Chemistry
Yale University


 
 
 

body weight vs. sail size vs. speed

Post by TWMARRI » Wed, 20 Sep 1995 04:00:00

Quote:
>Empirical Conclusions:
>1. He seems comfortable with a 6.7 m when Im with a 5.0 m sail.
>2. He is always faster than me when we're both fully powered up. In
>light air,  I am faster do to being more powered up than he.
>Is it just as simple as his weight and moment arm allow him to carry a
>proportianetly higher sail size or is something else going on?  Is
>there a complete theory on this??
>Much thanks.  As I am the better sailor in most other regards, this is
>driving me crazy!!

 In every form of racing that I have participated in, the smaller lighter
combination has the edge on acceleration and manuverability, but the
big motor will have more speed. Your only chance in racing this guy
is to keep jibing every time he closes the gap.

       Tom

Happiness is crossing the Bonner Bridge, southbound.

 
 
 

body weight vs. sail size vs. speed

Post by Pierre Jolicoe » Wed, 20 Sep 1995 04:00:00



Quote:
>Please help my buddy and me end a longstanding debate. I am 5-7 and 143
>lbs. He is 6-4 and 180 lbs. Is there a way to determine the
>theoretically equivalent sail size for us in the same wind conditions?

>Empirical Conclusions:
>1. He seems comfortable with a 6.7 m when Im with a 5.0 m sail.
>2. He is always faster than me when we're both fully powered up. In
>light air,  I am faster do to being more powered up than he.

it seems to me that the sail size difference is quite large for the
difference in weight.  I'm about 180 lbs while my wive is around 135.
When I'm powered up on a 6.5, she would likely be on a 6.0.  Perhaps,
on the outside, on a 5.5.  But, never on a 5.0....

when your friend is on a 6.7, rig a 6.0, and hang on!

Cheers,
Pierre

 
 
 

body weight vs. sail size vs. speed

Post by OREN L. REINBOL » Wed, 20 Sep 1995 04:00:00

Please help my buddy and me end a longstanding debate. I am 5-7 and 143
lbs. He is 6-4 and 180 lbs. Is there a way to determine the
theoretically equivalent sail size for us in the same wind conditions?
Assumptions:
1. We both have the same sailing ability.
2. We have equivalent  boards - he rides an Astro Rock when I have my
E-Rock.
3 We both have modern 1994 cambered slalom sails, his are Windwing,
mine are Hot.

Empirical Conclusions:
1. He seems comfortable with a 6.7 m when Im with a 5.0 m sail.
2. He is always faster than me when we're both fully powered up. In
light air,  I am faster do to being more powered up than he.

Is it just as simple as his weight and moment arm allow him to carry a
proportianetly higher sail size or is something else going on?  Is
there a complete theory on this??
Much thanks.  As I am the better sailor in most other regards, this is
driving me crazy!!

 
 
 

body weight vs. sail size vs. speed

Post by OREN L. REINBOL » Thu, 21 Sep 1995 04:00:00


Quote:
(Pierre Jolicoeur) writes:

>it seems to me that the sail size difference is quite large for the
>difference in weight.  I'm about 180 lbs while my wive is around 135.
>When I'm powered up on a 6.5, she would likely be on a 6.0.  Perhaps,
>on the outside, on a 5.5.  But, never on a 5.0....

>when your friend is on a 6.7, rig a 6.0, and hang on!

>Cheers,
>Pierre

I've gotten alot of good input on this thread, but one thing surprises
me.  Most comments have to do with weight differences,and their effect
on sail size eg. 25 lbs = .5 m (+ or -)  But where we really are
different is in our height.  I wonder whether a 6ft-4in 180 lb sailor
isn't able to carry a significantly larger sail than a 5 ft 7in 180 lb
sailor do to the leverage gained on the boom due to his height?  Does
anybody know? Maybe I'm just looking for excuses and I just have a slow
fin. Somehow, I don't think so.
-Obolt
 
 
 

body weight vs. sail size vs. speed

Post by D. Meye » Thu, 21 Sep 1995 04:00:00



Quote:
>Please help my buddy and me end a longstanding debate. I am 5-7 and 143
>lbs. He is 6-4 and 180 lbs. Is there a way to determine the
>theoretically equivalent sail size for us in the same wind conditions?
>Assumptions:
>1. We both have the same sailing ability.
>2. We have equivalent  boards - he rides an Astro Rock when I have my
>E-Rock.
>3 We both have modern 1994 cambered slalom sails, his are Windwing,
>mine are Hot.

>Empirical Conclusions:
>1. He seems comfortable with a 6.7 m when Im with a 5.0 m sail.
>2. He is always faster than me when we're both fully powered up. In
>light air,  I am faster do to being more powered up than he.

>Is it just as simple as his weight and moment arm allow him to carry a
>proportianetly higher sail size or is something else going on?  Is
>there a complete theory on this??
>Much thanks.  As I am the better sailor in most other regards, this is
>driving me crazy!!

A crude back-of-the-envelope calculation is informative here. I initially
thought that the 1.7 sq. meter difference in sail size was a bit large,
but I did the following calculation:

Assume that each sailor's center of mass is at approximately his waist
height, or about half his total height.

Assume they are both leaning out at the same angle, and for simplicity
assume horizontal (I know, that isn't the real situation, but it doesn't
change the result, since both of the computed torques would be decreased
by a constant factor).

Compute the torque available from each sailor in ft-lbs:

(height/2) * weight

(6.333 / 2) * 180 = 570 ft-lbs
(5.58 / 2) * 143 = 399 ft-lbs

Take the ratio: 570 / 399 = 1.43

Multiply this ratio by the sail area of the smaller sailor:

1.43 * 5.0 = 7.14

So it looks like the smaller sailor is actually carrying more sail area
relative to the amount of torque he can generate to hold it down than
the larger sailor! The big guy should be able to go to a 7.1!

Dave Meyers

 
 
 

body weight vs. sail size vs. speed

Post by Catherine Ori » Fri, 22 Sep 1995 04:00:00

Being a very light sailor, here is my experience about all that:

- First, I have a similar problem:
  . I most of the time start planing before the others,
    and therefore I'm rather quick in marginal conditions.
  . When there is more wind, I must take a very small sail and
    I'm very slow.

- My guess is that being light is a drawback for pure speed
  (I think the record man for speed is about 220lb)
  I also think that height does not change anything.
  But level of sailing has a big importance.

- I don't agree with statement like 25 lb = 0.5 m2 of sail,
  because it depends on the wind.
  One should compare sail sizes proportionally.
  e. g.
     6.0 / 7.5 = 0.8
     4.0 / 5.0 = 0.8
  So according to me, a difference of 1.5 m2 in 7.5 conditions
  is the same as a difference of 1.0 m2 in 5.0 conditions.

- 5.0 for 135lb = 6.5 for 180lb seems a little small to me.
  I would rather say that:
  5.5 for 135lb = 6.5 for 180lb, but ...
  ... it's really a hassle to be overpowered, so if you feel good
  that way, don't change!

- My opinion is also that the E-Rock has a rather old design now, even
  older than the A-Rock, and is really not a fast board.
  For instance, the Bic Adagio although rather old, has
  a better shape for slalom than the E-Rock.

- I used to sail a wave board (F2-Starlit) in slalom conditions,
  and I bought a slalom board (F2 Sputnik 275). It makes a huge
  difference in speed.
  I also have learnt to sheet in better, and have more powerfull
  sails since then.

- And finally, it does not matter so much to be the fastest.
  It's much more fun to duck jibe around a guy that just passed you
  and crashed in a jibe!

  (I just learnt to duck jibe this summer, after all it's not
  that hard -- got a rate of success of 1/2 after 3 days of practice
  on flat water with a 5.5m2.
  Those who can jibe and have never dared to try should
  go for it. It's really fun, and actually not harder than carve jibe.
  To make it, one should be planing, and flip the sail very early.
  That's all!)

By the way, thank you to all who responded to my question
about choosing a 6.5 sail. I finally bought a NP V8 and I love it.
It's powerfull and handles guts rather well.

Catherine

 
 
 

body weight vs. sail size vs. speed

Post by Sting-a-ling-a-ding-do » Sat, 23 Sep 1995 04:00:00

Quote:

> [stuff deleted ...]

>  (I just learned to duck jibe this summer, after all it's not
>  that hard -- got a rate of success of 1/2 after 3 days of practice
>  on flat water with a 5.5m2.
>  Those who can jibe and have never dared to try should
>  go for it. It's really fun, and actually not harder than carve jibe.
>  To make it, one should be planing, and flip the sail very early.
>  That's all!)

    Congratulations....  

Quote:
>By the way, thank you to all who responded to my question
>about choosing a 6.5 sail. I finally bought a NP V8 and I love it.
>It's powerful and handles guts rather well.

    I was curious if you have or tried to duck jibe the V8?  I used to be able
to duckjibe my old sails that had less of a foot but now with my VX LTD's I
am a little intimidated to try again...

Quote:
>Catherine

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body weight vs. sail size vs. speed

Post by p.. » Sat, 23 Sep 1995 04:00:00


Quote:
(TWMARRION) writes:
> >Empirical Conclusions:
> >1. He seems comfortable with a 6.7 m when Im with a 5.0 m sail.
> >2. He is always faster than me when we're both fully powered up. In
> >light air,  I am faster do to being more powered up than he.

> >Is it just as simple as his weight and moment arm allow him to carry a
> >proportianetly higher sail size or is something else going on?  Is
> >there a complete theory on this??
> >Much thanks.  As I am the better sailor in most other regards, this is
> >driving me crazy!!

        At your weight, I think using a much smaller board than him would
help increase your speed. I weigh 140lbs my big board is a Sputknik 270
world cup. When the wind picks up to 20+ I can sail my 8'2" Seatrend
with a 4.5 ( I've often seen people sailing 6.0 s when I'm using this
setup). Even though sails have a much wider wind range than they used to,
you will go faster with the right size sail, from my experience.


 
 
 

body weight vs. sail size vs. speed

Post by BATES Stev » Tue, 26 Sep 1995 04:00:00

One thing to think about is that the PBA sailors who take part in the
speed events usually put on weight jackets in order to use bigger sails.        

'Fat is fast' may not be far from the truth. Although I can't help thinking
that skill has something to do with it.        

Steve

 
 
 

body weight vs. sail size vs. speed

Post by Markus Huhtin » Fri, 29 Sep 1995 04:00:00


Quote:

>One thing to think about is that the PBA sailors who take part in the
>speed events usually put on weight jackets in order to use bigger sails.

>'Fat is fast' may not be far from the truth. Although I can't help
thinking
>that skill has something to do with it.        

>Steve

PBA sailors have wind minimums. According to my experience those wind
minimums ar quite high, too. Amateur racing with officially same wind
minimums is done with considerably less wind.

PBA sailors have the best and lightest equipment. They plane earlier and
get more speed than production board racers. You always rig so big sail
that you're overpowered. More weight gives you more speed then.

I've been involved in creating national racing rules for various classes
about ten years now. Every year smaller, lighter sailors insist that
there should be maximum sail size or the wind minimums should be lowered.
Big guys never want to limit sail size but agree on lowering the limits
as soon as they are convinced that new equipment will be competitive also
in lighter winds. Winning a race is more expensive for a big guy.

As long as we talk about racing in sub-planing conditions the light
sailors do not give big ones any chance. Odds are just about even above
9-10 knots with current equipment. Over 20 knots size, skill and stamina
combined seem to give good results.

We should agree that olympic sailing is completely different sport when
you compare it to PBA racing. I doubt that you will see any windsurfer  
weighing over 70 kgs in next year's olympic regatta. In fact, the
situation is just about same in any scheduled regatta without wind
minimums. If the start is to be at Saturday 10 am you can make 9 to 1 bet
that the wind will be blowing at steady 4 knots.  

 
 
 

body weight vs. sail size vs. speed

Post by Rick Colli » Sat, 30 Sep 1995 04:00:00

Quote:

>PBA sailors have wind minimums. According to my experience those wind
>minimums ar quite high, too. Amateur racing with officially same wind
>minimums is done with considerably less wind.

Actually, the PBA wind minimum is down to 8 knots!

That is the gain that can be made from large efficient sails, lightweight
advanced boards, and incredible skill.  Bjorn still planes most of the way
through his jibes at 8 knots, then pumps hard to quickly get back on a
plane.


BNR is into Telecommunications.  They have no opinion in this matter.

 
 
 

body weight vs. sail size vs. speed

Post by Frank Halliwe » Sun, 01 Oct 1995 04:00:00

Could be any number of reasons why your buddy sails faster.  But if
all things (such as ability) are equal, maybe its the Windwing sails
that are giving him the advantage.
                                  Frank

 
 
 

body weight vs. sail size vs. speed

Post by IGar » Wed, 04 Oct 1995 04:00:00

Here is what I use: A = WC/V^2.  V^2 is the square of the wind speed in
mph.  W is the body weight in pounds.  A is the sail area in square
meters.  C is a number telling you how powered up you are going to be.
The following is guideline on choicing C:
C:      What's going to happen

5        An expert can water start
8       I can water start consistantly
12     You start to feel powered up and your having fun
18     This is great you've got all the power you could want.
24     Your sail had better be flat, you've got as much power as you can
stand and          your going as fast as you can.
24+   Your overpowered and starting to get miserable
32     The most overpowered I've ever sailed.  Slam-dunked 4 times in a
quarter             mile to shore.  Pushing as hard as I could with my
mast hand and and          hanging on for dear life.  Survival, no fun.

Example:
 15 to 25 mph winds, 200 pounder.  V^2 = 225 to 625.  I'ld like to stay
between a  C of 6 to 18.  200*6/225= 5.3 meter 200*18/625 = 5.8 meter.
I'd rig a 5.5 or certainly not more than a 6.0.

Ivo