Careful how you apply that. It only applies in as far as to prohibit "hunting"...that is when a port tack boat starts to duck a starboard boat and starboard keeps going lower and lower making the port boat have to dig even deeper. You can call starboard all day long and tack as long as the port boat didn't have to take a new immediate action. Ethical? no, probably not, to call a starboard that you do not intend to utilize...Legal, can be.