Class Rules

The Viper 640 is a strict one-design keelboat where the true test, when raced, is between helms persons and crews, and not boats and equipment. This offers fair sailing and is the fundamental rule of the Viper 640 Class.

The boat is supplied as a strict one design, so no changes should be necessary. All Vipers should be the same except for minor upgrades approved by the Class Association.

Sail Button Request Form

Also available:

Championship Boat Inspection Form V6a August 2023 and

How to Prepare Your Viper for Inspection at a Championship_August 2023


Rules Introduction From The Technical Committee

If you have any questions about the Class Rules , please don’t hesitate to contact a member of the Technical Committee  We are here to help.

One of the attractions of the Viper for most owners is that the class rules are very simple and that the boat is strictly one design. The Viper philosophy incorporated in the rules is that “We want to go sailing, not use our time custom rigging our boats. We want an emphasis on sailing skills not differences between boats. We want to win or lose races on the water with the same exact boat as our fellow sailors” .

The Class Rules are written to prevent any changes from the standard boat that might be perceived to affect performance or boat handling, so that on the water each boat is the same. The few options to the standard boat that are allowed are minor. We want the boats to look and feel the same. A Viper owner should be able to step from one boat to another and feel right at home.

The class members have rejected changes to the rules that allow more expensive or complicated equipment or allow perceived variances between boats. When rule changes are reviewed, the Class asks :

“Does it make the Viper either (a) Easier or more comfortable to sail (b) Less expensive to own (c) More fun (d) A safer boat or (e) Does it improve longevity ? Then they ask (a) If it affects performance, can it be retrofitted to existing boats in a cost effective manner? (b) Will it be adopted by all boats (c) Does it accord with the Viper mission of providing  a fast, exciting , fun, easy, contemporary, high performance, one-design sport boat that is accessible to a wide range of sailors?”


Here are a few simple guidelines…

The Rules have three separate sections that are relevant to owners.

Part A is the “Fundamental Rule”. It states quite simply that you cannot change anything on the boat from the way it was originally supplied by the builder unless it is specifically allowed in Part B.

Part B lists the specifications for all components that are not supplied by the builder, eg. sails, and specifies any changes that are allowed from builder supplied boats. It also lists a few specific prohibitions and additional requirements that have to be made to builder supplied boats.

Owners don’t really have to concern themselves with Part C, unless there is anyone who thinks they have a boat that was not built either by Rondar or pre 1999 Performance Boats.

Part D lists any “interpretations” issued by the Technical Committee. They are mercifully few.

There is a simple rule of thumb.

If you are thinking of changing something to your boat, STOP! Look through Part B of the rules. If you cannot see a paragraph allowing the change – it will probably make your boat non-compliant. If you have any questions, the class technical committee is there to help. If the change has any impact on performance or boat handling, it will have to be addressed prior to racing at a class one design event.

The most common modifications allowed to the boat are; split tail mainsheet, GNAV, Cunningham.

Viper Class Rules V3.3 March 26, 2023 posted 082523