Beta Marine

Beta Marine

Sailboat Specifications

Hull Type: Fin w/spade rudder
Rigging Type: Fractional Sloop
LOA: 7.92 m
LWL: 6.17 m
S.A. (reported): 28.71 m²
Beam: 2.30 m
Displacement: 1,656 kg
Ballast: 694 kg
Max Draft: 1.46 m
Construction: Plywood/FG
First Built: 1958
Designer: Ben Seaborn

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Sailboat Calculations

S.A. / Displ.: 20.91
Bal. / Displ.: 41.92
Disp: / Len: 196.23
Comfort Ratio: 17.40
Capsize Screening Formula: 1.96
S#: 3.19
Hull Speed: 6.03 kn
Pounds/Inch Immersion: 545.56 pounds/inch

calculation mobile

2 nd ad half width

3rd ad full width

Rig and Sail Particulars

I: 8.15 m
J: 2.44 m
P: 9.45 m
E: 3.96 m
S.A. Fore: 9.94 m²
S.A. Main: 18.72 m²
S.A. Total (100% Fore + Main Triangles): 28.66 m²
S.A./Displ. (calc.): 20.88
Est. Forestay Length: 8.51 m

Sailboat Links

Designers: Ben Seaborn
Associations: Thunderbird Class Association
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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.