We open May 15, close Oct 15 every year.
Could open slightly sooner but boat valet does not start for us until around May 15 so not worth it.
Once you get past mid-Oct you run the chance of a short freeze. Even if not enough to crack pipes, your begining to get to the point where it is no fun breaking out the compresser and antifreeze and getting wet. Or pulling the dock with cold water pouring in your boots.