There are two fleets of ~34 boats each. Not a very big start really, but I think the race course is fairly short. F18 worlds usually has 60-90 boats per start, big opti and laser fleets have around 100. I think Etchells worlds this year had 90+ on one line.

Personally the biggest fleets I have sailed in would be F18 worlds (~60 per start), Etchells Jaguar Series (~60-70 per start), and Laser nationals (~100). Big fleets are lots of fun.