I think this puzzle is overrated with 3 stars. It was not that hard.
Because of the size of the ships a lot can be ruled out. And then it's just simple logic. No guessing, no 'what if' strategies.
Our statistics indicate that most people find this one relatively difficult. I think maybe you had some insight on it that is not as obvious to many others.
I see what you mean (about #80), and I agree with you: in retrospect, I don't think I would have given it three stars if I had made it now. Back then my feeling for stars was not as good yet, I guess...