If it can go to sea, it’s nautical. That is, if it has to do with a boat, ship, sailor, or one of those maps of the ocean that nautical people call a chart, it can be considered nautical.
You can wear khakis with sailboats or whales embroidered all over and not be the least bit nautical, but if you know that a rope is called a sheet and that hard to the lee means “duck and move to the other side of the boat,” there’s hope. The most nautical among us know what knot to tie in any given boating situation, which makes them both nautical and “knot-ical.”