Start A boat starts when, having been entirely on the pre-start side of the starting line at or after her starting signal, and having complied with rule 30.1 if it applies, any part of her hull, crew or equipment crosses the starting line in the direction of the first mark.
Note: in this definition there's no mention of 'normal position' of equipment or crew, like with finishing. If you sail along just below the starting line and the crew sticks out a hand, that hand may be crossing the line. Boats have been declared OCS because the back of the crew was over the line, but the hull of the boat was not.
Note: - at her starting signal or - after her starting signal. A boat starting at the same moment as the signal is not OCS, she has started correctly.
Note: - When returning after an OCS the entire boat has to be below he starting line before she can start. Just the bow, is not good enough. Take a background bearing of the line, so if you need to return, you know when you've sailed back far enough.
Note: ...and having complied with 30.1, .... That is the round the end rule. You have to sail across an extension of the starting line from the course side to the pre-start side. That is the reason the Pin-end committee boat - if there is one - will leave an opening between itself and the pin-end. Or create a space outside itself where boats can cross. A PRO should always make sure the coach-boats and spectators aren't blocking that area.
Note: The reason why most start lines are perpendicular to the wind is because that gives the sailors the chance to line up and keep their boat relatively in the same position by sheeting in or out, or by changing course towards the wind. There's no rule dictating this in the RRS, but the course has to be described in the SI and then it becomes a rule.
Note: There's also no time limit for starting in the RRS, but in the SI most Race committees will limit it to five or ten minutes.