The motivation for this paper was to provide computer support on the rules for sailing races. A brief overview is given of sailing terminology and racing rules. It is argued that a useful program for the racing rules should run on hand-held devices. The program should support an archive of rule scenarios, race training, self-learning of the rules, and analysis of rule disputes. SailRule is a freely available program intended to analyse and improve performance in applying the racing rules. The SailRule program has been implemented using the SuperWaba programming environment for hand-held devices. The user interface is described for the rules program. An explanation is given of the principles behind formalising and codifying the racing rules so that they can be efficiently implemented. Examples are given of how the program represents and analyses rule scenarios.