As a boy growing up in the midwest, I've seen two tornados up close and personal. The movement of the funnel cloud itself isn't straight line in my experience, so trying to outrun one is a guessing game, at best. If conditions were right for the formation and then a sighting, I'd be more in favor of beaching the boat and finding a low-lying area (such as a culvert) to lie in. Most tornados are not huge in diameter and will pass in a matter of minutes. Much like being in a hurricane, the problem with protecting yourself is less with the wind, but what is carried in the wind.
It's easy to say the odds are in your favor, but you won't convince the families of those who were killed in this recent situation. I'd keep the weather radio on, and an eye on the sky. And be ready to move.