I know you were very careful to make the vignetting seem accidental, but I can still tell it's vignetting. I just want it a bit more random. let some light touch the edge on the upper left. Then you'll have a really cool photograph.
Beautiful processing and strong diagonol presentation. I feel the top of the mast was important to have in the shot, as it currently leads my eye out of the image instead of bringing me back in the shot.
Looks like a nice place to take photos. IMHO this would have been better in landscape orientation, as it is now the poles(?) of the boat being cut off in the top left corner is a little distracting to me. I also think this could do with a very slight straighten :o)