|You do not need a lot of stuff to organize an LD tournament. You need a baseline of 40m length, made out of a rope or a ribbon, and a circle at the center with a radius of 2 m, i.e. a standard bullseye used in bomerang tournaments (marked with ribbon, chalk or paint). The end of the baseline is marked with a post on each side. The baseline is usually perpendicular to the wind direction. However, the thrower may have it rotated around the center as he wishes.|
For the throw to be valid, at least one foot of the thrower has to be on the ground inside the center half circle at the moment of release of the boomerang, and the thrower must NOT crossthe line at any time as long as the boom is in the air. The boomerang has to cross the baseline upon return, either directly or from behind, otherwise the throw is not valid (cf. drawing with valid / not valid boomerang flightpaths).
Officials & Spotters
The head official's place is near the throwing circle. He runs the tournament. He calls forth the throwers, ensures correct throwing from the center circle, and communicates with the head spotter on the field. There may be another official helping him in his task. In addition, there are two line judges at the left and right end of the baseline, respectively, to judge whether the boomerang crosses the line or is out of bounds.
Thereis a number of spotters on the field to determine the farthest point of the boomerang's flightpath. We suggest the spotter arrangement shown in the schematic on the left. You have to be aware that if the boomerang is more or less flying over you, it is difficult for you to judge where the projected path on the ground actually is. Only by spotting from a distance off to the side are you able to determine the apex of the flightpath accurately. Therefore, we suggest placing a row of spotters to the left and right ofthe expected throwing corridor, respectively, with a ~20m distance between the spotters within one row. You can also align the two rows in a a staggered manner to get a better coverage. The spotters should be spread such that all throws, including the shortest and farthest ones, can be precisely spotted. Send the farthest spotter sufficiently far out, as there may always be "lucky" throws. One of the head spotter's duties is to ensure that the spotters are distributed correctly.
Don't use more spotters than necessary to fulfil the task, because with too many spotters they tend to walk about and have chats ! 6 is the minimum (+1 head spotter), 12 should be enough in all cases. Here's what you have to do as a spotter: Follow the boomerang on its way out with your extended arm and stop when you think it reached its farthest point. Then project that point down onto the ground by lowering your arm vertically. Fix the point on the ground with your eyes and direct the head spotter to that point. At least one other spotter will do the same, so the head spotter will have to position himself such that the closest 2-4 spotters are happy with the result. Often, there is a little arguing about the farthest point, but that's the interesting part of spotting: discuss until there is agreement ! The spotters that could not see the apex of the flightpath very well should not interfere ! The maximum distance of the boomerang is now defined as the distance from the head spotter to the center of the throwing circle. If you have a Laser Rangefinder (e.g. a Bushnell) you can measure the distance immediately, otherwise you have to place a marker in the ground and measure the distance at the end of the round with a (steel !) tape.
We estimate the accuracy of the measurement with this "spotting" method is 2m in the best case, 5m on average, and more if the spotters are not placed very well or if they are not paying attention. It is actually helpful to distribute thin wooden sticks (~2m long) to the spotters, with the help of which it is much easier to follow the flying boomerang at its farthest point and drop the perpendicular to the ground.