[Rhodes22-list] Centerboard and Sail Trim and Leeway

[Hank]

Leland,

In your scenario it is not critical because you are trying to go to a point
the is more on a broad reach.  However, if you look at my version and
consider this scenario.

Here, we want to sail from A to C.  With the board down we can sail directly
there.  However, with the board up, we end up at B instead of C.  We then
need to tack and sail the extra distance.  The speed gained with the board
up does not make up for the extra distance we had to sail.

Hank

On Fri, Jul 31, 2009 at 6:51 PM, Leland <LKUHN at cnmc.org> wrote:

>
>
> 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
> --
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