WOWSA 13.1 – While open water swims are overwhelmingly completed doing freestyle, a small number of athletes attempt and complete open water swims, including marathon swims and channel swims, using the butterfly stroke. In order for a swim to be considered a Butterfly Swim, the entire distance must be swum butterfly as defined by the following rules:
WOWSA 13.2 – From the beginning of the first arm stroke after the start (either from shore or in the water) to the finish of the swim (either onshore or in the water), the body must be kept on the stomach. While the athlete is swimming, he is not permitted to roll onto his back at any time or take any freestyle arm strokes or leg kicks, or breaststroke arm strokes or leg kicks, or do sidestroke of any type. A swimmer is allowed to stop swimming in shallow water as he approaches the shoreline and walk up on shore to clear the water as an athlete swimming freestyle would do.
WOWSA 13.3 – The athlete can stop swimming butterfly only during voluntary stops or feeding stops. During stops of any kind, the athlete must stay in the same spot and can tread water to rest or take fuel (food) or hydration (drink). They can stretch their arms, body, neck, back or legs, but they must stay in the same location.
WOWSA 13.4 – To qualify as a Butterfly Swim, both arms must be brought forward together over the water and brought backward simultaneously throughout the swim. The only acceptable exception to this rule is when a large wave, whitecaps or a boat wake prevents one or both arms from being brought forward simultaneously. In this case, the next arm stroke must continue brought forward together simultaneously.
WOWSA 13.5 – Breathing in a Butterfly Swim can be done forward or to either side of the body.
WOWSA 13.6 – All up and down movements of the legs and feet must be simultaneous. The position of the legs or the fee need not be on the same level, but they shall not alternate in relation to one another. The breaststroke or whip kick may not be used exclusively or interchangeably with the dolphin kick while doing the butterfly kick while doing the butterfly stroke at any time during the race.
WOWSA 13.7 – If the above rules are not adhered to, the swim will be defined as a standard (i.e., freestyle) swim.