Certainly mind set has a lot to do with it! If you think your boat/sails/etc. are 'slow' chances are you are not going to push as hard when you should. "What's the Use" is the mindset.

In Dennis Connor's book, "No Excuse to Lose" he talks about it, and Stuart Walker has one called simply "Winning", which goes much deeper into the psychological aspects of the mind being pre-disposed to win...or lose, regardless of new boat, new sails, etc.

Connor makes a good point though. He says to go out and buy the best stuff you can, get what ever it is that the class champions are using, the same boat, the same sails, etc. so when you get out on the race course, you can't blame your boat/sails/etc. In effect, you will give yourself -No Excuse to Lose-, so you must push yourself harder to win, or admit you just suck...some people just can't go there, must be the boat!