Peter- Me being a straight-shooter (multiple puns intended ), I assume this is a straight shot, converted to B&W, and then fiddled with to simulate pen and ink.
I was about to suggest cloning out all those dust spots, but that would take a lot of time doing it . Leave them in- what the hey.
In a strange way, I like this.
Charlie
Charlie, you're right about the fiddling. The 'dust spots" are light mist and I removed a bunch of them but it's really tedious and I wanted a "more or less" clear sky.
Tom, the black spot is a buoy (pronounced "boy" in our neck of the woods) and I agree it would look better without it.