Straighten shoreline.
Dupe Background, USM at 20, 40, 0. Adjust layer opacity to taste.
Levels adjustment layer setting white point on sky and
black point on black sail.
Curves adjustment layer applying a slight "S" curve.
Selective color adjustment layer targeting white > change to blue
for the sky. Apply a gradient to delete the resulting blue in foreground.
Cloud brushes for hazy clouds.
Paint With Light.