[Rhodes22-list] Centerboard and Sail Trim and Leeway

[Leland]

David,

Everything I've read indicates that you are right.  Many of the times that
I've measured the effects of the centerboard I've noticed more than a ten
degree improvement into the wind.  However, every time I put the board down
I slow down.  Every time I raise the board I speed up.

Hopefully this picture will come through:


http://www.nabble.com/file/p24764138/Sail%2BSpeed.ppt Sail+Speed.ppt 

Let's assume you're sailing from point A to B with the board up.  Doesn't
matter how much you drift because you're still going from point A to B.  If
you put the board down you can sail more into the wind and you are able to
sail from point A to C.  To get to point B you would then need to sail from
point C to A.  Even if you weren't sailing slower with the board down,
wouldn't it take you longer to go from point A to C to B than sailing
directly from point A to B?

Am I missing something?

Unless I want to go more into the wind, it still seems like the best reason
to put the board down is to knock the barnacles off.

Lee


Yesterday I got the chance to sail in 5-10 kt wind and relatively flat 
water.  I set the boat up on a beam reach (apparent wind 90 degreees).  The 
course was was 060 M by my steering compass.  We were able to do about 
.5  - 4 kts SOG by the GPS. 

With the board down our  COG (Course over ground) was 055-057 M 
With the board up out COG  was 045-048 M 

Although my steering compass is not compensated and thus has unknown 
deviation, since it was held steady at 060 the deviation has no importance 
here.  Lowering the board reduced leeway by about 10 degrees.  Lowering the 
board had no observed effect on SOG although wind variation could have 
hidden a small effect.  Based on these results I see no reason to sail with 
the board up unless in very thin water and one very good reason to sail with 
it down. 

David Walker 
-- 
View this message in context: http://www.nabble.com/Partial-Mainsail-tp24647946p24764138.html
Sent from the Rhodes 22 mailing list archive at Nabble.com.