I'm sure you've all heard the proverb regarding assumptions, about how the act of making them makes an "ass" out of "u" and "me." I always thought it was fairly clever, and some good advice to boot, but I'd never really applied it to sailing. Calling tactics, after all, involves making countless assumptions—maybe you call them educated guesses—about the near-term future: Is the wind is going to shift direction? Is it going to increase, decrease, or stay steady? What are your opponents going to do over the next 30 seconds? Over the next 10 minutes?