I find it runs large. I bought a new jacket in the fall and I could have gone a size smaller. Not the end of the world, but not how I'd like it to be.
Personally, it's the last mail-order jacket I will buy. Just too much hassle to have the wrong size.
For buoy-racing, I'd consider dinghy gear
. The most comfortable people in the crew I ran with wore dinghy
smocks and the like. The freedom of motion is a lot better.