Chris Stevens,
If you like numbers, here are some. If you want the details i can
fax or mail you two pages. I have made the following calculations
with a vega loaded to 6500 pounds, indices would come out slightly
different with an empty boat but who sails with an empty boat.
LENGTH/BEAM RATIO. vega 3.4, on the border of narrow and normal.
Narrow boats have less initial stability but often more stability at
extreme angles. Narrow more easily driven, especially in waves.
WATERLINE LENGTH/DRAFT RATIO. Vega 6.0. Normal values 5.0 to 7.0.
Higher values indicate shoal draft.
BALLAST/DISPLACEMENT RATIO. Vega 31% Usual value for crusing boats
is 30 to 40, so vega tends to be at light end which we knew from Per
Brohall.
DISPLACEMENT/LENGTH RATIO. Vega 238. Values can be from 50
(ultralight) to greater than 300 (heavy). Vega classifies as
moderately light.
SAIL AREA/DISPLACEMENT RATIO. Vega 14.0. Under 15 is low, 15 to 18
is moderate, greater than 20 is high. So I guess we are in heavy-
weather sailers, not club racers.
MOTION COMFORT RATIO. Vega 25.8. This falls well into the
category "Greater Comfort" (in seas) rather than "Average" or "Less
comfort". Higher numbers mean more comfort, and the scale of numbers
depends on the length of boat, but for our length, 22 or 23 would be
the border between greater and average. An unloaded vega would be
20, in the middle of average comfort when tossed on the waves. This
category was cooked up by naval architect Ted Brewer.
CAPSIZE FORMULA. Vega is 1.71. (empty 1.87). 2 or less is okay for
ocean racing. 1.65 is a low value and low values are very good
against capsize. With value of 1.9, would not want to sail
shorthanded in the ocean. This was also cooked up by some expert
but just off-hand i have forgotten who. The formula is BEAM divided
by the following .... cube root of (displacement in pounds divided by
64) The beam i guess is in feet. The displacement over 64
represents cubic ft of seawater displaced .... arghhh will we never
get rid of these foolish imperial units and get everybody on metric.
I did not find a stability index ratio in this article.
John
J.B. Sprague, Salt Spring Island, British Columbia.
No. 1492 Flagfish.
