Only since a year, dacron sails are allowed. There are also rules governing the safety of the persons on board and that of the competitors. The Committee-General checks to see if the sk tsjes meet the demands stipulated in the rules. The board is somewhat infamous in skipper-circles for performing checks even during a match. This is nessecitated by the fact that a clever skipper may make some sneaky changes to enhance the speed of his ship over the course of the match week.
Sailing is a competitive sport combining the elements wind and water.