I am asking this, b/c I have done an independent Iron race in the past. The swim was very open. My next big race is a branded Ironman and I know I am looking at a whole different ball game with the crowding.
In particular, I am amazed that the quick times I see posted in Ironman swims. I belong to a large pool and I observe/swim with many many IM participants. I see them struggle in the pool, yet then I see some pretty quick times in the actual IM. What is that all about? Are they really dropping the hammer on race day, or is there a draft effect if you hold your own in the thick of the action?