I learned it in Basic Boating class when I was 9. After that I just remembered the formula. That's why I'd forgotten all about it. Plus I rarely used it once I had GPS. If you're traveling a short distance you really don't need it. In fact you don't even need a compass card (which most boaters never get) for most cruising. Close is close enough. But if you're traveling long distance being off by even a degree or two could have you missing the island you're looking for. Just ask Amelia Earhart. Oh that's right, she was never found. Draw a course line from Vancouver to say Hawaii. Now change the course by a couple of degrees and see where you'll end up.