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THUNDERBIRD

• Designed by Ben Seaborn
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THUNDERBIRD - Drawing

General Information

Hull Type: Fin w/spade rudder
Rigging Type: Fractional Sloop
Construction: Plywood/FG
First Built: 1958

Dimensions

Length Overall (LOA): 7.92 m
Length Waterline (LWL): 6.17 m
Beam: 2.30 m
Draft (Max): 1.46 m

Weight & Ballast

Displacement: 1,656 kg
Ballast: 694 kg

Sail Plan

Foresail Area: 9.94 m²
Mainsail Area: 18.72 m²
Total Sail Area (calculated): 28.66 m²
Sail Area (reported): 28.71 m²
I (Fore Triangle Height): 8.15 m
J (Fore Triangle Base): 2.44 m
P (Mainsail Hoist): 9.45 m
E (Boom Length): 3.96 m

Engine & Systems

Performance Ratios

Hull Speed: 6.03 knots
SA/Displacement (Calculated): 20.48
SA/Displacement (Reported): 20.91
Ballast/Disp Ratio: 41.92%
Displacement/Length: 196.23
Comfort Ratio: 17.40
Capsize Screening: 1.96
S-Number: 3.19

Notes

Some THUNDERBIRDS have been built of molded FG with aluminum spars. A "cruising deck" design was introduced. Most have been built from plans now supplied by the class association. See the class web site for details.