The Viper 640 is the fast and fun one-design that almost didn't make it. Shortly after being named the 1997 Boat the the Year, the Viper lost its builder and went out of production. The design was so well loved that in 2005, a small group reestablished the class, recruited a new builder, and started a grassroots fleet. 20 hulls quickly grew to over 125. A keelboat in name only, the swift and highly responsive Viper 640 is a great fit for sailors looking for a modern, moderately athletic, and high-performance sportboat. viper-sailplan.gif

Boat Specifications

Length Overall: 21ft 4 in (6.40 m) 
Length Waterline: 19 ft 1 in (5.7 m)
Beam: 8 ft (2.4 m)
Displacement:749 lb (340 kg) 
Ballast: Lifting Bulb Keel: 
271 lb (123 kg)
Sail Area: Main/Jib: 
252 sq. ft (23.4 sq. m) 
Sail Area: 
Spinnaker:425 sq. ft (39.4 sq. m) Designer: Brian Bennett, Kiwi Yacht Design Builder: Rondar Boats

Viper 640


viper-vang.gifSmall Boat High Load Utility Car-HC8418Track System A CB Mast 80 3/4"-380729 mm Carbo double w/ Swivel and Becket-343Track End Kit-System A CB Round-380829 mm Double w/Swivel-342Micro Block Thru-Deck-24229 mm Fixed Carbo-348
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Gnav strut

The Viper cockpit is very clean with a gnav in place of a traditional vang. The new 8:1 Harken gnav replaces the slider system with a captive bearing car designed for compression loads. The Harken IN8418 utility car removes most of the friction to make the system more powerful, reducing the need for a very high purchase, and making it far easier to use under load. 

viper-jib-halyard-leads.gifCarbo Ratchet Cheek-2137Aluminum Cam-Matic® Cam Cleat-150Stainless Steel Eyestrap-073Micro CamMatic II Kit w/Wire Fairlead-47040 mm Carbo T2 Block - 214940 mm Carbo Swivel-34029 mm Carbo 90 Degree Alternate-353Jib Lead Car w/Eyestrap-45040 mm Fixed Carbo-265029 mm Clew Block Assembly-37129 mm Carbo Stand-up-349X-Treme angle fairlead-476Cam-Matic Kit w/X-Treme Fairlead-459Dinghy jib Track Lead-453
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Jib Halyard Fine-Tune

For cranking up the luff tension in fresh wind, the Viper's jib halyard is deflected through a 8:1 fine-tune. The double-ended system uses Micro Carbo Cams with X-Treme Angle fairleads, making it easy for the forward crew to adjust without leaving the rail.

Jib Leads

The 2:1 ratchet-controlled jib sheet runs through Carbo T2s on the clew to low-profile pinstop cars for trim angle adjustments. In addition to moving the cars forward to round the foot of the jib, Viper sailors can also improve light-air performance by removing the top batten to keep the leech open.

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