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1 Chapter 2 Chapter 3 Chapter 4 Mainsails Genoas and Other Jibs Spinnakers Asymetrical Spinnakers Cruising Spinnaker (The UK Flasher) Dousing Sock (The UK Stasher) Staysails Drifter Blast Reacher Storm Sails Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 |
The curved sides
of a spinnaker make the computation of area a complicated process. It
is therefore an almost universal practice in the sail-making industry
to compute the area as if the sail were a rectangle. We follow that practice,
and the area shown on a price list is the product of the luff length times
the maximum width. The actual area will vary from about 70% to 85% of
the rectangular area, de-pending on the type of spinnaker. The
length of the luffs and the maximum width are computed from the I and
JC dimensions in accordance with a formula which is common to almost all
of the rating rules for handicap racing. This formula yields dimensions
which have worked well in practice for many years. For that reason, we
use those dimensions in building spinnakers, even if the particular customer
has no intention of racing his or her boat. For those interested, the
maximum width equals 1.8 times JC, and the maxi-mum luff length equals
95% of the square root of the sum of I squared and JC squared. |
Three
basic spinnaker types are available: Tri– radials, Fatcats and Matrix
Cuts. All three have radial heads and radial clews. The Tri–radial
and the Fatcat both have horizontal panels in the center section, separating
the head from the radial clews. These horizontal panels are cut with curved
edges to permit proper control of the draft of the spinnaker. The
Fatcat differs from the Matrix and Tri-Radial in that it is designed to
be very flat for close reaching. The break point between the bottom of
the head panels and the top horizontal panel occurs much lower in the
sail, and the total surface area of the sail is less, especially in the
head. As a consequence, a Fatcat usually has fewer horizontal panels than
a standard tri-radial for the same boat. It is normally made of stronger,
heavier material, and it doubles nicely as a "chicken chute" for heavy
weather running.
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| The Matrix Cut is a variation of the tri-radial. It omits the horizontal panels altogether; the radial clews are extended up to the middle of the sail, where they meet the head. The full radial panel layout allows for precise articulation of cloth threadline to match primary sail loadings. Each panel is shaped individu-ally by our computer cutting machines to distribute shaping smoothly and evenly, with a minimum number of horizontal seams. Fewer seams make a smoother surface for the wind to flow over. The Matrix creates the lightest, strongest spinnaker for a given cloth weight. The rocked vertical panels ensure a distortion-free sail, even when close reaching. |
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