[Rhodes22-list] Re: Pointing

[ed kroposki]

Slim:

	Isn't planing a result of lift?

	Send Peter that picture you posted of the European leeboards.  His
idea of dual centerboards is already in use just not in the center.

Peter:
	
	I do not pretend to be astute with the terminology as you.  I stated
that my opinion was a wild guess based on my Windex. My line of discussion
is that we have seen questions on the list about pointing.  It is my
observation that new guys with diamond boards are usually the ones asking.
Maybe the answer just is learning how to point.  We have had some good
discussions on this.
	Have you noticed that Fred is reticent about stating whether he has
a centerboard or a diamond board.  Maybe he does not know the answer.  One
solution would be to put on a scuba mask, jump over the side and see,
presuming the board is down.
	Thank you for the reference on the Dennis Connor book.  What I did
not tell Fred is that often you learn to sail better by reading the books
referred to on this list.  
	I am waiting for you to get your Rhodes 22 in the water so that your
answers will be more boat specific.  Comparing the R22 to an iceboat?  If
you want to see how Lake Hartwell boats point, come on down.  One sail with
Rummy and all the numbers will blend.
	What progress are you making getting your boat shipshape?  Maybe you
should just trailer it over to Stan and have him get it water ready.  At the
rate you are going you might be as old as Stan is before you get it wet.
 	
Ed K

-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Steve Alm
Sent: Thursday, September 23, 2004 3:26 AM
To: Rhodes
Subject: [Rhodes22-list] Re: Pointing

Peter,

Hold on, thar!  "Lift" from the keel, CB and rudder?  The underwater
appendages are symmetrical with the hull and cannot provide any lift.  They
only serve to prevent lee way, or to provide lateral resistance.  That part
I agree with.  Brad might have a better description, but lift happens when
air (or presumably water) has to travel farther around one side than the
other, creating a difference in pressure between the two sides.  Lift is
created by the curved shape of the sail or airplane wing and will stall if
not going fast enough.  The keel, CB and rudder do not have that kind of
shape.  I'm with you on the rest as far as pinching vs. pointing goes, but
it's the sails that stall out, not the keel, CB or rudder.

Slim

On 9/22/04 7:58 PM, "Peter Thorn" <pthorn at nc.rr.com wrote:

 Hello Ed,
 
 If you verify that you're able to point your R22 35 degrees off the true
 wind, I certainly would like to visit Lake Hartwell to see that.   Perhaps
 it's the apparent wind, the combination of the boat's velocity across the
 bottom combined with the true wind direction, that's making you think
you're  pointing so close. On a reasonably fast boat like R22, the apparent
wind  angle can move quite a bit forward.  In an extreme example such as
iceboats  (that travel many times the true windspeed) the wind indicator
points almost  straight forward.
 
 Are your headsail sheets led to tracks at the foot of the cabinhouse roof?
 That, I think, would certainly improve pointing.
 
 It's good to be aware of the difference between pointing and pinching.
 Sailing too close to the wind can cause the underwater foils to slow down
 then stall.  That's pinching.  When the keel, cb and rudder stop producing
 lift, the boat will start to produce a lot of leeway, or sideways drift.
It
 is very difficult to detect leeway when aboard the boat that's making all
 the leeway.  The bow points higher, so the skipper might think he's
pointing
 pretty high because the sideslip is so hard to feel.  To avoid this
 condition, foot off and keep the boat moving.  After regaining speed, head
 up a little.
 
 If you have a GPS you can verify your pointing angle by measuring your
 heading (not the direction the bow is pointing), tack to the other tack,
 measure heading again and divide the angle difference by 2.  I think
someone mentioned this not too long ago on the list.
 
 I too have wondered about the diamond board, and would guess Phil Rhodes
 original cb is pretty hard to improve on.   A while back Roger wrote a very
 scientific sounding comparison, do you recall that?
 
 Perhaps you Lake Hartwell guys should conduct on-the-water pointing trials
 and settle the issue.
 
 PT