Question 1
Must the string described in the definition Sail the Course, when drawn taut, lie in navigable water only?

Answer 1
Yes, definition Sail the Course refers to ‘a string representing a boat’s track’. A boat’s track cannot pass over dry land, nor can it pass through non-navigable waters or through prohibited areas. It follows that, when drawn taut, the string must lie entirely in navigable waters; it passes to one side of non-navigable shallows, prohibited areas or other obstructions, and follows the path of a river.

Similar considerations apply to both the requirements in the definition Finish to cross the finishing line from the course side, and to pass through a gate from the direction of the previous mark. A boat is required by rule 28.1 to ‘sail the course and finish’. To do so, her track must satisfy the three tests in (a), (b) and (c) in the definition Sail the Course. Therefore the taut string described in the definition is constrained to lie in navigable water as described above.

The diagram illustrates boat A’s taut string when a headland obstructs boats on a leg of the course. The course described in the sailing instructions was: ‘After starting, round Mark 1 to port and then finish.’ After rounding Mark 1 to port, A sailed as close to the headland as possible given her draft and the depth of the water at the time she was passing it. A’s string is shown touching Mark 1 and following A’s track around the shallow water at the north end of the headland. Because of the headland the ‘course side’ of the finishing line was north of the line. Therefore, to be recorded as having finished, A was required to cross the line from north to south (see the definition Finish). If A’s taut string was not constrained to lie in navigable water, it would follow the straight line across the headland from Mark 1 to the finishing line. Then, the ‘course side’ of the line would be south of the line, and A would be required to cross the line from south to north.

Question 2
In tidal waters, should navigable waters be considered at high tide or low tide?

Answer 2
Neither. Whether water at a particular location is navigable or not depends on the draft of the boat and the depth of water at the time the boat sails past that location.

GBR 2000/5