The way the Hobie 16 Worlds works is:1- You can just show up and try to qualify on site.
There's a two-day qualifying regatta held in advance of the main event. At the 2010 Worlds in Weihai, China, there were 54 teams trying to qualify; 45 advanced to the semi-finals. It sounds easy, but you never know how many are going to try to qualify on site or how many are going to advance. For example, at the 2004 Worlds in Mexico, there were 120 teams attempting to qualify and only about 45 advanced.2 - You can pre-qualify for the semi-finals.
Each region (North America, for example) is given a certain number of "pre-qualified" spots. The way you earn one of those spots is by competing in Hobie Class Association points regattas in your area and/or by how well you do in the regional (North American) championship. That process is explained on the HCANA web site (http://www.hcana.hobieclass.com/
>Rankings > Worlds Qualfying)
For the event last year in China, the North American region had a hard time filling their spots. It was an expensive trip and not many people could afford to go to China for 10+ days.
Once you're in the semi-finals, you sail in half the races (not necessarily every other one) and rotate boats between each race. After 3 days of racing, there's a cut party and the top half of the fleet continues to sail for two more days, generally rotating boats every race. It can be a grueling schedule - especially if you sailed in the qualifying series - that's 7 days straight. It also means that there's little time for sightseeing.
I have to admit, the two worlds I've been to (Guadeloupe in 2000 and Mexico in 2004) were the most fun I've had with my clothes on. Especially Mexico.