Part 2, Section C When Boats Meet— Room to Pass and Tack at an Obstruction
Rules 19 and 20 are the rules that apply when you are sailing near obstructions. Remember, an obstruction is an object large enough to require you to make a substantial course change to miss it if you were one of your lengths away and aiming directly at the largest part of it, whether or not you are actually aiming right at it on the water. In other words, it is a hypothetical test to determine if the physical size of the object qualifies it as an obstruction. For instance, imagine a 50-foot barge. If you were in a 20-foot boat aiming at the middle of its side, you would obviously have to make a large course change to avoid hitting the forward or aft 25 feet of it. So it ranks as an obstruction even if dur - ing the race you were only aiming at the last foot of its transom. (See discussion of the definition Obstruction.) Also remember that a boat racing is an obstruction to you only when she
has the right-of-way over both you and the boat(s) near you that are about to pass her (see the definition Obstruction), or if you and the other boat(s) have to avoid her under rule 22 (Capsized, Anchored or Aground; Rescuing). But note that no vessel under way, including a boat that is racing, is ever considered a “continuing” obstruction.
