This photo is more surreal than real. I thought the photo needed just a little touching up and then a little more and a little more.... until it because this.
If you interested in what I did: The photo was a broad daylight shot, or at least late afternoon. The reflection on the water darkened the sail on the sailboat so I pulled it up in Gimp and used the scissor to select just the sail -- I like that tool because of it automatic form fitting alogrithm means I have to click on fewer points.
Next I used the "Color| Curves" tool to lighten up the sail. Next I used the "Select | Invert" tool so that now I had all but the sail selected. I used the "Color| Desaturate" to take the color out of the the rest of the picture.
Then I selected the sky using the "Scissor" and then used "Filter| Render| Clouds| Plasma" to put a brightly colored sky in the scene. Then I used "Color|Desaturate" to take out all that color but leave the cloud-like effect.
Next came the "Color| Colorize" tool to change the sky to a blue hue and darken it down. It looked great now, but the reflection on the water looked out of place with out a moon. So I used the Airbrush tool with a fuzzy circle brush and a low opacity setting ( so I could make several passes and paint the moon in). I also changed the setting of the brush from "normal" to "overlay"
I went to town painting the moon using several different sizes of the brush first a large bright area, then a real bright center. Then using a very large brush I took quick passes around the moon to better blend it in. When I had what I wanted the moon still did not seem to blend it to well -- too much of a contrast difference. So I got a royal-bluish color on my brush and made a few passes -- I liked that so much I made some random passes around the sky with it --it added a better texture to the clouds.
While I had the brush like that I made a few passes over the water to add some blue.
Voila -- sundown sailing