Rule 17
Action by stand-on vessel
The stand-on vessel holds course and speed — but may act when the give-way vessel clearly isn't, and must act in extremis.
In plain language
Stand-on does not mean helpless. First, hold your course and speed so the other vessel can plan around you. Second, once it is apparent the give-way vessel is not acting, you may maneuver yourself — but a power-driven vessel in a crossing should avoid turning to port for a vessel on her own port side. Third, when collision can no longer be avoided by the give-way vessel alone, you must take whatever action best avoids it. The give-way vessel stays obliged to keep clear throughout.
Easily confused with
- Rule 16 — Action by give-way vessel
Give-way acts early and substantially (Rule 16); stand-on first holds course and speed, and acts only when the give-way vessel doesn't (Rule 17).