Dennis:  Now if you want another 9 seconds…………ditch the spinnaker pole and 
declare “no pole” and go straight to your ASYM……………Ron C.

 

From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Joel Aronson 
via CnC-List
Sent: Wednesday, May 07, 2014 8:59 AM
To: Dennis C.; cnc-list@cnc-list.com
Subject: Re: Stus-List Technical sail discussion

 

Dennis,

 

My limited understanding of aerodynamics is that if the foot is not on the dock 
then the higher pressure is allowed to "leak" under the foot to the low 
pressure side, diminishing lift.  That's why they now have tips on airplane 
wings.  If the cabin causes upward deflection, that may be more than offset by 
maintaining the pressure differential.  But either way, you are +6 sec./mile!

 

Joel

35/3

Annapolis

 

On Wed, May 7, 2014 at 8:51 AM, Dennis C. via CnC-List <cnc-list@cnc-list.com 
<mailto:cnc-list@cnc-list.com> > wrote:

I recently re-filed my PHRF certificate to get +6 seconds for a roller furler.  
Subsequently, I just had the luff my Mylar/Kevlar 155 cut down to fit on the 
furler.  My sailmaker cut a bunch off the foot.

I was chatting about loosing the sail area with one of the really good sailors 
in the club. He said it may actually be a good thing that the foot is higher 
off the deck. He said with the older narrow IOR designs, deck sweeper genoas 
may cause the slot to be less efficient. Might increase the bubble in the main.

In my simplistic mind I kinda see where he's coming from. The slot gets 
restricted at the deck by the cabin. The lower part of the air flow would get 
pushed upward into the bottom of the main. A higher foot allows some flow to 
escape and keep the air flow lines smooth in the lower slot.

Does this make sense?

Dennis C.
Touché 35-1 #83
MandevilleLA

Sent from my iPhone
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-- 
Joel 
301 541 8551 

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