Who gives way when one boat overtakes another?

The overtaking boat always keeps out of the way of the boat being overtaken (COLREGs Rule 13). This applies to every vessel, sail or power, and it overrides the usual sail-before-power order.

Rule 13 of the collision regulations says that any vessel overtaking another shall keep out of the way of the vessel being overtaken. It applies whatever kind of vessels they are: a fast yacht overtaking a slow motor boat must keep clear of the motor boat, and a motor boat overtaking a yacht must keep clear of the yacht.

A vessel counts as overtaking when she comes up on another from a direction more than 22.5 degrees abaft (behind) the other's beam. In practice, if you are coming up from behind and at night you would see only the other vessel's white stern light, and neither of her sidelights, you are overtaking. If you are in any doubt, the rule says to assume you are overtaking and act accordingly.

The obligation lasts until you are past and clear. You cannot overtake, pull ahead, and then claim to be the stand-on vessel under the crossing or port-and-starboard rules. Any later change in the bearing between you does not make you a crossing vessel.

How to overtake safely:

• decide early which side to pass on, and give a wide berth;
• on a sailing boat, passing to windward of another sailing boat will take her wind, so passing to leeward is often more courteous, though slower;
• do not cut back in close ahead of the boat you have passed;
• in a narrow channel, do not overtake unless the other vessel can safely let you through. Rules 9 and 34 give sound signals for asking (two prolonged blasts and one short for her starboard side, two prolonged and two short for her port side) and agreeing (prolonged, short, prolonged, short).

The vessel being overtaken should hold her course and speed so the overtaking vessel can plan around her.

More in the book: Chapter 13, The rules of the road