[Alberg30] Re. Sail area.

[Dave Terrell]

thanks for the info. I appreciate your observations

>>> nauticallyyours-maggie at sympatico.ca 07/23/03 04:33PM >>>
Michael, #220 wrote:
Also, I don't think luff X foot/2=sail area will work for genoas. I
think that formula requires a right angle, and there aren't any on
Genoas.

The right angle is LP (load perpendicular) from the luff to the clew of
the Genoa. No need to use calculus as the missed area from the triangle
below the LP makes up for the extra area from the clew to the head.

The right angle from the luff is usually a few feet above the tack -
or, using a tape measure held at the outer edge of the clew ring, find
the shortest distance to the luff. This is the way we measure genoas
when reducing them from their original size, 150% etc., to 135% etc. The
length of the foot is not the governing factor.

If you have a specific point at which you wish the clew to be located,
first check to see if the sheeting angle will be suitable for the
current location of your winches, then use the tape measure from the
point where you wish the clew to be located and find the shortest
distance to the forestay (the right angle), mark that point on the
forestay and  note the measurement, then measure from the point at which
the sail will be attached at the tack to that mark on the forestay. A
total distance for the maximum desired length of the luff will also help
your sailmaker design the perfect sail for your individual needs. The
three measurements, total length of LP, LP intersection at forestay to
tack of sail and maximum length from tack of sail to head of the Genoa,
should be all that is needed as computers do wonders with the rest. In
each case, the two sides of the two triangles you've given the sailmaker
also gives him the length of the two hypotenuses (leech and foot).

Here are the measurements we have on file for the A30:

I=36.00'        J=10.5'        P=31.00'        E=14.30'

Standard Mainsail    =    240 sq. ft.
No. 1, 150% Genoa =    290 sq. ft.
No. 2, 135% Genoa =    243 sq. ft.
No. 3,   98% Genoa =    166 sq. ft.
Storm Jib =                     65 sq. ft.
Storm Trysail =                78 sq. ft.

Just a thought - I notice the Alberg regulations specify a specific
width of material, perhaps these should be reviewed as most fabrics are
now available is widths of 54 inches, thus reducing the number of seams,
time and labour. Today's fabrics are superior in strength from even a
few years ago and don't need the narrower panels which were regulated by
the production of narrower material.

Maggie.
Strathgowan, #400
P.S. I hope I haven't stepped on any toes or opened a can of worms, but
if I see room for improvement I'll usually say something, as a few of
you already know. ;-)

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