To whet your appetite and keep your writing fingers limber, take a good look at the photo, or let a prompt settle in your mind. Set a timer for a reasonable amount of time, be that five, fifteen, or thirty minutes. Then start writing.
Write a locked room mystery involving this crew on this boat.
Write about your favorite summer adventure from childhood. Who was there? What made it great? When was the last time you felt that good?
Write a guide for people who are thinking about buying a boat. What should they consider before taking the plunge?