This was a classic sunset photo.  A number of sailboats were out racing far from shore.  Fortunately, the sailboats happened to be in a good position, just as the setting sun dropped below some evening clouds.  Perhaps there's some classic good luck in many of the classic photos.

This is the one of the reasons photographers lug around those telephoto lenses and tripods.  The only question in this photograph was whether all the elements were going to come together.  I had the camera on the tripod and was following the sailboats' motion.  I was also watching the setting sun.  When the sun had dropped clear of the cloud and taken a position which I estimated would be at an intersection of two 1/3 lines in relation to the sailboats, I released the shutter.   I think I was pretty lucky.  On the other hand, I had prepared for the good luck.