101.3 BUTTERFLY
.1 Start — The forward start shall be used.
.2 Stroke — After the start and after each turn, the swimmer’s shoulders must be at or past the vertical toward the breast. The swimmer is permitted one or more leg kicks, but only one arm pull under water, which must bring the swimmer to the surface.
It shall be permissible for a swimmer to be completely submerged for a distance of not more than 15 meters (16.4 yards) after the start and after each turn.
By that point, the head must have broken the surface. The swimmer must remain on the surface until the next turn or finish. From the beginning of the first arm pull, the body shall be kept on the breast except at the turn after the touch of the wall where it is permissible to turn in any manner as long as the body is on the breast when leaving the wall. Both arms must be brought forward simultaneously over the water and pulled back simultaneously under the water throughout the race.
.3 Kick — All up and down movements of the legs and feet must be simultaneous. The position of the legs or the feet need not be on the same level, but they shall not alternate in relation to each other. A scissors or breaststroke kicking movement is not permitted.
.4 Turns — At each turn the body shall be on the breast. The touch shall be made with both hands separated and simultaneously at, above, or below the water surface [effective September 23, 2013]. Once a touch has been made, the swimmer may turn in any manner desired. The shoulders must be at or past the vertical toward the breast when the swimmer leaves the wall.
.5 Finish — At the finish, the body shall be on the breast and the touch shall be made with both hands separated and simultaneously at, above, or below the water surface [effective September 23, 2013].