This is real pretty, such a nice angle that you used. The light is devine. I see that you had half the people fooled as well. Deserved better score, but I think think this is an image you'll be enjoying for a long time.
I think it is REAL, because the sun is low enough to produce a rainbow, and the sky is gray enough to have the required mist or rain. Love the scene with all those identical boats in a row.
This is a lovely scene and I like the subtlety here. In a very gentle, pretty way you could be fooling us with the rainbow. In either case, I like the end result.
I'm just commenting here because I'm going through commenting on everyone's photographs, guessing real or fake.
I like the composition in this a lot. When you sent it to our team I thought to myself... "what a serene and very nifty photograph" At first I thought the rainbow was edited in. =) So, great job! <3