[Public-List] working jib size

Tue Feb 7 16:29:36 PST 2012

Glenn -
 The official Chesapeake Bay A30 Rules working jib is an 82% - this is
LP/J not an area ratio.

I don't know about roller furling, but below is a table with the Luff
Perpendicular worked out for each of the
jibs shown in the A30 Sail Plan. The Chesapeake Bay One Design rules
specify these numbers as max dimensions for the Working Jib and the #1,
but say only that the #2 must  be smaller in every dimension than the
#1.  
The J shown in the Sail Plan is 10 feet 5 inches.

          Luff   Foot Leech   LP    LP/J%
 Working  30.00  10.25 25.75  8.52  0.82
 #2       32.00  15.00 30.25 14.06  1.35
 #1       34.00  19.00 33.50 18.09  1.74

 LP can be found directly from the three sides of a triangle as :
 LP = sqrt ( foot^2 - ( (leech^2-foot^2-luff^2)/(2*luff) )^2 )

 Mike
Rinn Duin #272
-----Original Message-----
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[mailto:public-list-bounces at lists.alberg30.org] On Behalf Of
brooks.glenn at comcast.net
Sent: Tuesday, February 07, 2012 7:21 PM
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Subject: [Public-List] working jib size

Anybody have an idea of what the ideal working jyb measurements might be
for the A-30 with roller furling? 

I have an older jyb that came with Dolce that I never use, but today
just dusted it off and measured at (luff 24' , foot 13'). This seems a
bit long in the foot for a working jyb, but maybe it was designed as a
110% laper under the old cca rules. North sails quoted a working jyb at
36' luff X 10' foot, which is about a 100% of the foretrangle area. my
old jyb is actually about 24 Sq ft smaller than North's proposed jyb. I
am going to put it on tghe boat and do a little sea trial in the few
days, but am wondering in advance how the sailing characteristics may
differ between the two different sail configurations and how it might
affect the boat. 

Thanks for any info you all might be able to offer. 

Glenn P 
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