When to reef? Honestly, I wasn't sure. The wind was now up to a solid 13 knots, tickling 15 with every indication of getting stronger. Yet the 35-foot boat with a full-batten, square-top main seemed to be handling everything fine. In fact, as we galloped past Old Mission Light in Grand Traverse Bay, my sister and her daughter, both nonsailors, were below in the galley, happily making grilled cheese sandwiches and tomato soup without a hint of seasickness. Not bad for a sailboat I was originally reluctant to take on a four-day cruise on Lake Michigan.