The 'member of a recognised yacht club' (Rule 10) must be on board at _first_ gun, and so with all the other racing rules.
One of the race officers must very carefully watch the alignment as the starting time (_precisely_ five minutes after first gun) approaches, and the other officer should watch the chronograph and shout the word 'fire' at the fraction of a second. 'Should the gun miss fire the simultaneous lowering of the blue peter is the signal to start' (Rule 17). The officer attending to the starting line should carefully note whether 'any part of the hull, spars, or other equipment' (Rule 17) of any of the yachts 'be on or across the line _before_ the signal to start is made.' If so, the recall numerals of such boats should be at once displayed, and kept displayed until they return and recross the line or give up the race (Rule 12). The second race is started in the same way, the preparative flag C being hoisted when the starting gun for the first race is fired.
Sometimes there is an interval of time between these actions; but there is no difficulty in starting races every fifteen minutes in strict accordance with the rules, if the officers know their duties and the signalmen are well trained.
The work of starting shows the necessity of appointing _two_ race officers; and, subsequently, during the racing it enables at least one officer to be always on duty. The officers should watch the racing as much as possible, and should they see or learn that any yacht has broken any rule, they should disqualify her whether she be protested against or not (Rule 30).
'Should it be necessary during a race to shorten the course' (Rule 4), the officers will order 'the signal flag denoting the race' (or races) to be 'hoisted under the white peter; or, in case of fog or darkness, two guns' to be 'fired,' to show that the race is to finish with the round about to be completed, 'or at such mark as the sailing committee or officer of the day may appoint.' In practice, the sailing committee never interferes with the race officers.
Of course the time allowance, if any, is adjusted to the altered distance (Rule 4).
If there be more than one round in a course, each yacht should be timed at the end of each round; but there is no rule to this effect. The time at the end of a round or race is taken when any part of a yacht's hull or equipment _first_ cuts the line. When the competing yachts pass the race officer, he should also notice whether any of them 'show an ensign conspicuously in the main rigging' (Rule 30), this being the preparative signal of a protest; and consequently, the race officers must be prepared to receive such protest 'within two hours of the arrival of the protesting yacht,' but they cannot decide it. This rests with the sailing committee.