Completed this one in three hours -one hour a day. I just wanted to do a sub.
I consider paintings like this to be more like a doodle. I didn't spend any time doing thumbnails to find good a composition or color scheme. I didn't even play around with drawing different kinds of submarines to paint!
Still, doing something like this without any kind of planning (and just seeing where it takes me) is fun to do from time to time.