For our Club and Winter dinghy racing we race around fixed marks, starting from a a committee vessel (to give a windward start) and finishing at a fixed line. This line is not very long (around 150m) and we do not want boats who have finished to come back over the line and preventing the Finish officials from seeing sail numbers of finishing boats. This is the SI as currently written: "After starting correctly, the finish line between the orange pole at the battery in the North dinghy park and the black mark F shall rank as an obstruction except when finishing or completing a round. Boats contravening this SI will be scored DSQ without a hearing. This changes RRS 63.1, and A5."
The problem that has arisien is that a boat having finished (and cleared the finish line and marks) could then sail down through the line with the defence that they were no longer racing and no longer subject to the SIs. How do we and is it possible to make this instruction bullet proof?