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Sailboat Specifications

Viper 640

Fractional Sloop · Lifting Keel

Designed by Brian Bennett · Built by Viper Boats (Usa)/Rondar · First built 1996

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LOA 21.08 ft  ·  Beam 8.17 ft  ·  Displacement 700.00 lb  ·  Sail Area 252.00 ft²  ·  Fractional Sloop  ·  Lifting Keel
About the Viper 640 Sailboat

Designed for pure performance and competitive racing, the Viper 640 has earned a strong reputation as one of the most exciting one-design sports boats on the water today. Built for a crew of three, this sleek planing hull delivers an exhilarating sailing experience that appeals to experienced racers looking for a fast, responsive, and highly competitive platform. The Viper 640 is particularly well suited to inshore and coastal racing, where its agility and speed-focused design can be fully exploited. Its relatively simple rig and manageable size make it accessible enough for a small but skilled crew, while still offering the kind of intense, high-performance sailing that keeps seasoned racers coming back. The boat is known for being physically demanding in a rewarding way, rewarding good technique and sharp tactical decisions. With an active class association and a dedicated racing community, the Viper 640 benefits from strong fleet presence at regattas across North America and beyond. For sailors seeking a boat that prioritizes speed, competition, and fun over comfort or cruising capability, the Viper 640 is a compelling and well-regarded choice.

Dimensions & Specifications
LOA (Length Overall) 21.08 ft / 6.43 m
LWL (Waterline Length) 19.08 ft / 5.82 m
Beam 8.17 ft / 2.49 m
Max Draft 4.83 ft / 1.47 m
Min Draft 1.83 ft / 0.56 m
Displacement 700.00 lb / 318 kg
Ballast 185.00 lb / 84 kg
Sail Area (Reported) 252.00 ft² / 23.41 m²
Design & Construction
Hull Type Lifting Keel
Rigging Type Fractional Sloop
Construction FG
Designer Brian Bennett
Builder Viper Boats (USA)/Rondar
First Built 1996
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Frequently Asked Questions

What is the Viper 640's sail area to displacement ratio?

The Viper 640 has a Sail Area to Displacement ratio (SA/D) of 51.22. Values between 14–18 are typical cruising sailboats; 18–22 is cruiser/racer; over 22 is performance racing.

What is the Viper 640's comfort ratio?

The Viper 640 has a Ted Brewer Comfort Ratio of 3.35. A ratio over 30 indicates good offshore comfort; over 40 is very comfortable offshore.

Is the Viper 640 safe for offshore sailing?

The Viper 640 has a Capsize Screening Formula value of 3.68. Values under 2.0 are considered acceptable for offshore sailing; under 1.8 is ideal.

What is the hull speed of the Viper 640?

The theoretical hull speed of the Viper 640 is 5.85 knots, calculated from its waterline length.

How much does a Viper 640 weigh?

The Viper 640 has a displacement of 700.00 lb and a length overall (LOA) of 21.08 ft.

Who designed the Viper 640?

The Viper 640 was designed by Brian Bennett, first built in 1996.