Strength of wind vs sail size

Strength of wind vs sail size

Post by Francois Dubois » Thu, 30 Apr 1998 04:00:00


Hi all,

I do not own an anemometer so I do not know for sure what kind of wind I
usually sail in. I have no problem in choosing the right sail when I am on
the beach but I would not be able to say with accuracy how many knots was
the wind.
When I read windsurf magazines this creates an even bigger confusion since
the pros use 7.0m sail in 25 knots (this should mean that in Maui it would
be difficult to plane with a 5.0m most of the days - which is not the
case!!!!).

The "common" recreational sailor weights about 75kg / 165lbs. For this
"common" sailor ( able to do waterstat, planing jibe, jumps and a few other
tricks) what would be the best suitable size of sail (freeride sail) for
the following wind strength : 10knots - 15 knots - 20 knots - 25 knots - 30
knots - 35 knots.

Any advice is greatly appreciated,

Francois Dubois

 
 
 

Strength of wind vs sail size

Post by NLW TFW » Thu, 30 Apr 1998 04:00:00

Francois --
This has been discussed at great length recently, and no quick answer would do
the previous discussions justice. Find them via dejanews for the REAL answer.

In the meantime:
* On any given piece of water at any one time, "normal" sized people will be
using sails of the average size plus or minus 30% or more. That's a range of
meter or two, reflecting preferences, skills, sailing style, point of sail,
sail type, wind consistency, offshore vs onshore wind, board size and type, fin
size and type, and sailin' whut ya rigged to avoid rerigging.

 The stronger the wind, the smaller the sail, unless ya switch boards type or
size, sailing style, point of sail, onshore/offshore, etc., or the wind fills
in or gets holier.

Examples for me, at 180:
* 15-20, 15-25, 15-30, steady 15, => biggest sail I got (the 6.8).
* If the 6.8 is too much most of the time (wind > 20 all the time) => 5.2.
* steady 20 (yeah, right) => 5.8.
* 5.2 is usually too much (> mid 20s most of the time) => 4.7.
* Spray flying occasionally (mid 30s or so?) => 4.2.
* Spray flying often (40ish?) => 3.7.
* White-out (spray and chunks of water flying everywhere consistently) => 3.2
* Consistent liquid smoke => 2.8.

But then I change board size and everything shifts by maybe half a meter. Ya go
in the waves, and everything shifts down by a meter 'cause yer power comes from
da waves. Ya enter a race and rig up an extra 1.5 meters so there are ZERO
lulls.

And yet another guy my size and skill level, on an identical board, 20 feet
from me, sailing in about the same manner, might PREFER another half meter or a
half meter to a meter less. Your OWN experience and preferences are worth more
than all the advice we could give you on this one.

Mike \m/
Never Leave Wind To Find Wind

 
 
 

Strength of wind vs sail size

Post by Joxer » Fri, 01 May 1998 04:00:00

    Francois, I just happen to have WS mag " suggested" slalom
sail sizes for a 175lb sailor. Maybe a starting point for you:
    5-15 knots:  7.3 sl         7.8race  
    14-20 knots: 6.3sl         7.3race
    18-24 knots: 5.5sl         6.8race
     20-26 knots: 5.0sl        6.5race
      24-30 knots: 4.8sl       6.3race          

      These numbers are a couple of years old. The biggest change
is the 5-15 knots category; very managable and FAST 8.5s and 8.7s on
the market.  These still seem pretty close to what I see on the water.
       Most seem to prefer race sails for 6.5 and up, wave/sl sails for
the smaller sizes where control is the issue.  Any help to ya?

 
 
 

Strength of wind vs sail size

Post by Wolfgang Soerge » Fri, 01 May 1998 04:00:00

Quote:

> When I read windsurf magazines this creates an even bigger confusion since
> the pros use 7.0m sail in 25 knots (this should mean that in Maui it would
> be difficult to plane with a 5.0m most of the days - which is not the
> case!!!!).

Depends on what the "pro" is doing: trying to win a race, just sailing
for
the fun of it on flat water, doing freestyle, riding waves for fun or
doing
a heat in a wave competition. You may find everything from 8.5 - 4.0
used in
these "25 knots". Everyone will feel having rigged right.

(for the rest, try a search in dejanews)

Wolfgang
--
Wolfgang Soergel                  
Lehrstuhl fuer Nachrichtentechnik / phone: ++49-9131-857781
Universitaet Erlangen-Nuernberg  /  fax:   ++49-9131-858849
Cauerstrasse 7             /     email:

D-91058 Erlangen, GERMANY /
http://www.nt.e-technik.uni-erlangen.de/~wsoergel