However, should there be insufficient numbers competing in any one class then the minus-one rule will be applied. 9.1 Competitors are allowed twenty minutes between scheduled events However, in the event that a swim-off is required to determine eighth place it shall take place not less than one hour after all involved swimmers have completed their heat. See FINA SW.3.2. While the intent is to perform all strokes as described by FINA, visually impaired swimmers require some considerations due to the lack of, or limited amount of sight. The referee and judges must use their discretion.
Some specific advice is given below.
A blind swimmer, B1 or low vision B2, may have difficulty making a simultaneous touch with the shoulders remaining in the horizontal plane if the swimmer is in close proximity to the lane line. In this case disqualification should not occur. A disqualification will only occur if the swimmer gains propulsion from the lane line. Likewise, at the turn or finish a simultaneous touch may be impossible. The start in Freestyle, Breaststroke, and Butterfly races may take place from the starting platform, beside the platform, or in the water.