One boat keeps clear of another if the other can sail her course with no need to take avoiding action and, when the boats are overlapped on the same tack, if the leeward boat can change course in both directions without immediately making contact with the windward boat.

Keep clear illustrated
File:Keep clear duck.gif
File:Keep clear cross.gif
File:Keep clear tack.gif
File:Keep clear gybe.gif
animated illustrations wanted
File:Keep clear luff.gif