John,
The formula for the spinnaker is LeechLength * ( 4* HalfWidth + FootLength ) /6
The limit is 210.9 sq.ft (19.60 sq.m) and usually LeechLength is 6.40 to 6.45 (21 ft 1in +/- 1 in) and spinnaker pole length is 2.25 (7 ft 4in)
The limit for Australian Gem's is 250 sq.ft or 23.22 sq.m. and they survived. (but should be used with a 8 ft spinnaker pole for better stability)
Yours spinnaker is approx 170 sq.ft...
The average spinnaker has a FootLength 93% of HalfWidth
As the Gem was designed for tha Micro, the standard "genoa" should not exceed LuffPerpendicular = 2.25, this is just a 110% (or even less) genoa.
Phil
----- Original Message -----
Sent: Sunday, February 10, 2008 12:55 AM
Subject: [MicroClass] Re: Gem 550
hI pHIL-
THANKS FOR YOUR INPUT
Sails quoted by sanders were without reference to current rule,
probably from the original design data (1979)- don't forget we have
no official micro class here. Now I'm concerned with the best club
handicap to our local rules....
I presume that class rules limit 18.50 refers to main+foresail in m2 -
I think in feet and inches... 18.5 m2= 199sq ft. Also, the jib/genoa
sizes you quote- these are luff x LP?
Reference the Sanders quote, I do not know what the dimensions for
foresail refers to, luff x foot or luff x LP; spi could be luff or
max length * maw width or foot
I still have the original sails for my Gem:
jib (19ft 5in luff x 5ft 10" perpendicular from luff to clew (LP))
genoa (19ft 7in luff x 89.5" LP)
main + spi I'll measure them soon
You state that area with jib is less than rules -fine, that's why you
must have a small jib as well as a genoa. I use it a lot in heavy
weather (F6/7) with double or triple reefed main and when sailing on
my own. When sailing on my own, I can rig a light boom (6ft bamboo)
from the forestay to hold the jig goosewinged without leaving the
tiller to set a whisker pole.
You state "spi too small"- I think you mean "spi is smaller than
allowed"
> regards
> John GAZELLE #40
> Poole
>
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