Sail the course

A boat sails the course provided that a string representing her track from the time she begins to approach the starting line from its prestart side to start until she finishes, when drawn taut,
(a) passes each mark of the course for the race on the required side and in the correct order,
(b) touches each mark designated in the sailing instructions to be a rounding mark, and
(c) passes between the marks of a gate from the direction of the course from the previous mark.