moving the boat more into the image (over the sand bar and closer to the viewer might help).. the boats wake is hitting the horizon in the Hi Res, a bit of a problem.. but Only IMHO good luck and cool image

I think there are a few problems with lighting and implicitly with the shadows.. see the big rock formation in the lower left corner of the image ? well at the top of this formation there is a shadow that clearly puts your light source somewhere center-right over your image's top margin thus contradicting your choice in moving that cloud formation whose well lit margins indicate that they are concealing another light source of an opposite orientation ( look at the rock on the beach in the source image ). Also taking this into consideration there might be some things to ponder as to who's shadowing who regarding the close vicinity of the castle and ( or on itself ) the rock formation close-by. That's just my two cents regarding tweaking to perfection.. other then that it is a good composition and it had a nice feel to it.

Congrats!!