I cropped a lot of objects in this scene, namely, the boat and the rows of trees on the bank of the lake. I want to highlight the lake–the (cut off) trees and boat are there to provide some context. Imagine how not including the boat and the trees would change the scene.
I placed the boat on third left of the frame. I cropped the boat because I wanted to show more of the lake. A partially shown boat is recognizable as a boat. It does act as a strong foreground which gives the photo stronger appeal. And because it acts as a strong foreground and a big portion of the boat is shown, the boat needs to be sharp.
I cropped the trees because their reflection is enough to convey their form. Also because the trees frame the scene, little to be shown. If I had shown more trees, they would look awkwardly placed too closed to the edge of the photo.
Inside the Frame series dissects how a photo incorporates composition patterns. Every photo is annotated to clearly reveal each photo composition technique used when framing the scene. Studying these photos will help you take better pictures yourself.