You are not following a line feature
I would say you are, the fact that you do it by following a series of headings does not mean you are not following it, I would certainly not want to be the one arguing this in court. Even if agreed you are not - 5-600' from shore may NOT be enough to avoid all the guys who ARE following the coast as a line feature, who of course will be travelling the other way round. Personally I would rather go round anticlockwise or stay over land.