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Olympic triangle
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Olympic triangle
The Olympic triangle is a sailing course used in racing dinghies, particularly at major regattas like State, National and World Titles and was used at the Olympics. (Olympic sailing now uses quadrilateral courses)
The remainder of this article should be read in conjunction with Sailing Instructions for the specific regatta or the International Sailing Federation (ISAF) Race management page, the Racing Rules and particularly Appendix L.
The traditional Olympic triangle course consists of a lap (starting with a beat or work to windward from the starting line to the top, weather or windward mark, a first reaching leg to the wing mark (also known as the gybe mark), a second reaching leg from the wing mark to the bottom or leeward mark), a hot dog (a beat to the top mark with a square run back to the bottom mark), another lap and then a beat to the finish line, which may have one end at the top mark, or may be set beyond the top mark. When the finish line is set beyond the top mark, the sailing instructions need to specify whether the top mark remains a mark of the course on the final leg or whether it is to be ignored. There are generally 9 legs, 5 equal to the length of the windward leg (4 beats and a run) and 4 reaching legs (2 of each reaching leg), so once the leg lengths are known the total course length can be calculated. Roundings are generally to Port. Many sailing instructions only specify the length of the windward leg and the total course length, but see below on the use of the law of sines, trigonometry table and spreadsheets to calculate the angles and other leg lengths.
Traditionally the configuration of the triangle is an equilateral triangle (3 equal sides and 3 equal angles of 60 degrees) with a ratio of the windward leg to a reaching leg being 1:1. In that case the course length for the 9 legs described above is 9 times the length of the windward leg. The angle at each point of the triangle is 60 degrees. The windward leg is generally aligned with the average wind direction.
Another configuration is a triangle with a right angle at the wing mark and 45 degrees at the top and bottom marks. In this case the ratio of the windward leg to a reaching leg is 1:0.7071 and the course length for the 9 legs described above is 7.8284 times the length of the windward leg. One would imagine that a triangle with 45 degrees at the top and bottom marks and 90 degrees at the wing mark would provide ideal reaching conditions on both reaching legs, provided the windward leg runs straight up wind. However, the wind will often shift during the race and the Committee may not always be able to shift marks to re-align the course to the new wind direction. With a 60, 60, 60 triangle, if the wind shifts 15 degrees either way, one of the reaching legs will be a 45-degree broad reach, while the other will be at 75 degrees to the wind and will be a close reach.
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..
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Olympic triangle
The Olympic triangle is a sailing course used in racing dinghies, particularly at major regattas like State, National and World Titles and was used at the Olympics. (Olympic sailing now uses quadrilateral courses)
The remainder of this article should be read in conjunction with Sailing Instructions for the specific regatta or the International Sailing Federation (ISAF) Race management page, the Racing Rules and particularly Appendix L.
The traditional Olympic triangle course consists of a lap (starting with a beat or work to windward from the starting line to the top, weather or windward mark, a first reaching leg to the wing mark (also known as the gybe mark), a second reaching leg from the wing mark to the bottom or leeward mark), a hot dog (a beat to the top mark with a square run back to the bottom mark), another lap and then a beat to the finish line, which may have one end at the top mark, or may be set beyond the top mark. When the finish line is set beyond the top mark, the sailing instructions need to specify whether the top mark remains a mark of the course on the final leg or whether it is to be ignored. There are generally 9 legs, 5 equal to the length of the windward leg (4 beats and a run) and 4 reaching legs (2 of each reaching leg), so once the leg lengths are known the total course length can be calculated. Roundings are generally to Port. Many sailing instructions only specify the length of the windward leg and the total course length, but see below on the use of the law of sines, trigonometry table and spreadsheets to calculate the angles and other leg lengths.
Traditionally the configuration of the triangle is an equilateral triangle (3 equal sides and 3 equal angles of 60 degrees) with a ratio of the windward leg to a reaching leg being 1:1. In that case the course length for the 9 legs described above is 9 times the length of the windward leg. The angle at each point of the triangle is 60 degrees. The windward leg is generally aligned with the average wind direction.
Another configuration is a triangle with a right angle at the wing mark and 45 degrees at the top and bottom marks. In this case the ratio of the windward leg to a reaching leg is 1:0.7071 and the course length for the 9 legs described above is 7.8284 times the length of the windward leg. One would imagine that a triangle with 45 degrees at the top and bottom marks and 90 degrees at the wing mark would provide ideal reaching conditions on both reaching legs, provided the windward leg runs straight up wind. However, the wind will often shift during the race and the Committee may not always be able to shift marks to re-align the course to the new wind direction. With a 60, 60, 60 triangle, if the wind shifts 15 degrees either way, one of the reaching legs will be a 45-degree broad reach, while the other will be at 75 degrees to the wind and will be a close reach.
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..