Olympic Triangle - Length of Windward Leg and Course - Time Versus Distance

Time Versus Distance

Many dinghy classes have a target length for a race for the first boat. This time might take into consideration the age of competitors, how physically demanding the class is and how physically demanding the conditions are. 100 minutes is often used by Herons in Australia as an informal target (not specified in the Sailing Instructions). It is generally accepted that the whole of the course ought be completed in a race to ensure that all points of sailing are tested by competition. This requires consideration of the length of the course for a given class of boat in given wind strength.

When dinghies are sailing in displacement mode (as opposed to planing mode) they will take longer to complete a leg than if they are planing. The relationship between the time taken to complete a beat, compared to a run, compared to a reach will vary between classes at a given wind speed and by a class at varying wind speeds, with a significant change once boats are consistently planing on reaches (and runs).

Empirical evidence for Herons at 8 knots (15 km/h) of breeze on Botany Bay, Sydney with a windward leg length of 0.8 nautical miles (n.n.) saw a beat of 19 minutes, a reach of 9 minutes and a run of 13 minutes (non-planing conditions). With an equilateral triangle the traditional triangle, sausage, triangle, and beat to finish would require a windward leg of approx 15 minutes to allow for a completion time of approx 100 minutes for the first boat. In 8 knots (15 km/h) for a Heron the indicated windward leg length is approx 0.6 n.m..

Any Principal Race Officer wishing to have completed courses within a target time will need timing of completion of beat, reach and run legs over a wide range of wind conditions for the particular class to enable the setting of an appropriate length course (9 times the windward leg length in the traditional configuration described above). Race committees need to ensure that the sailing instructions regarding course length for each particular regatta have taken into account the aims of the Organising Authority in relation to all of target times, course length and course completion and that the achievement of some are not inconsistent with the achievement of the other(s). The possibility of changing leg/course lengths during a race needs to be considered to allow for changes in wind conditions.