Never go out alone and do check your blood glucose levels before you start. If you are out on the water for more than an hour, do continue to check your blood glucose level and never exercise without taking extra carbohydrates with you. I suggested that you take lessons before you crew or kayak, but I tell you, you need lessons before you sail alone. This is an intimidating sport. Many of us know people who will volunteer to teach us.
Sailors are interesting lot especially in their own boats.
If you really want to know how to sail and be safe doing it go to an accredited school. When our children were young we spent a week at the Annapolis Sailing School, not because we didn't know how to sail, but because we wanted our children to understand the importance of safety on the water. You will need to learn how to change direction in the water, tacking, which moves the sail from one side to the other, catching the wind. Changing direction means that the boom swings across the deck with frightening regularity. Before long, you'll be the one shouting those two words, and it will be you who is maneuvering the sail boat in the channel.