I don't know about your PHRF area, but Chesapeake requires that the furler
drum is above deck AND you have the UV patch (heavy cloth) on both the foot
and leach of the sail. Then you get the six seconds.
Gary
----- Original Message -----
From: "Martin DeYoung via CnC-List" <cnc-list@cnc-list.com>
To: "Dennis C." <capt...@gmail.com>; <cnc-list@cnc-list.com>
Sent: Wednesday, May 07, 2014 1:32 PM
Subject: Re: Stus-List Technical sail discussion
Calypso's headsails were also cut for a furler with the higher foot, now
about 18" off the deck.
We still get a significant "speed bubble" in the main at the mid to upper
wind range for the light and heavy #1s. The bubble shows up 6' to 25'
(off the deck) on the mainsail.
From my miss-spent youth crewing with serious race programs I expect there
to be an advantage to the deck sweeper type headsails, more so for the
early IOR type sail plans with big fore triangles and smaller mainsails.
The engineers may reference something about an end plate effect.
Over the last 10 years of club racing Calypso with roller furling
headsails we see a significant decrease in performance at the low end of
the wind range, especially in acceleration. Side by side with another C&C
43 that had newer, non-furling headsails Calypso was left in the dust as
the wind built from calm to 5 knots. Once the TWS was above 7 knots the
speed difference was much less but the newer sails still pointed higher.
After reading about your +6 per mile for the roller furler I need to take
a close look at the PHRF-NW book and re-file Calypso's data. We are still
using the old IMS/IOR type measurements.
Martin
Calypso
1971 C&C 43
Seattle
-----Original Message-----
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Dennis
C. via CnC-List
Sent: Wednesday, May 07, 2014 5:51 AM
To: cnc-list@cnc-list.com
Subject: Stus-List Technical sail discussion
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 sail maker cut a bunch off the foot.
I was chatting about losing 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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