Yes, that is a good point and something I didn't consider until you mentioned it. Especially the mountains. I had a few occasions where I thought I was close enough to known mountainous regions and couldn't see them but, I just never gave it much thought. I thought (at the time) it might be due to fog or some other weather phenomenon. The "docks" situation never really hampered or presented me with any real problems so, I just chalked it up to curvature of the earth along with fog, heat waves or any combo of weather conditions. I guess if I was trying celestial navigation, I might have been more aware of it.
Then again, knowing me, I probably would've just gotten close enough to where I could see the landmarks.