The Viper 640 is the perfect one design performance race boat. It combines the stiffness of an open keelboat with the acceleration and planning abilities of a dinghy. The Viper is a joy to sail with a precise and exhilarating feel on the helm, a comfortable open cockpit for 3 people, strict one-design class rules and ease of launching at any tide.
Read The Reviews"The Viper 640 was our unanimous choice as Performance One Design Winner". - Sailing World
It's not a dinghy. I don't think you can call it a keelboat. It's something in between. Upwind, the boat's fine bow slices through the water. Downwind, it gets up and planes. - 48 North Magazine