I like the composition. Depending on what you are trying to convey, I'd take this piece in a number of directions.
If it's the idea that this man is solemnly sailing, then I would keep him as he is and maybe darken the scene a touch. The light reflecting on the sail sort of disperses one's feeling of loneliness.
If it's the idea that this man is enjoying a nice sail, I would consider brightening him up a bit so that the viewer can connect with him a bit.
