Well, I feel the lighthouse is absolutely necessary in this composition, for it gives the total balance to the existence of the moored boat, compositionwise as well as in its reflecting just the colours that the boat has.
The bit of red in both, boat and lighthouse, nicely contrast with the general blue of see, distant bank and sky.
I also like the division in three horizontal layers (again: water, distant)shore, sky) which add to the overall calmness of the composition and enhance the impression of serenity.
The evening light adds to it.
Now I am curious what the original, the "in-camera" crop was like? But just curious. No need to show me, really... I'm just wondering...