1.9 Give-Way & Stand-On (Rules 16–17)

Why Rules 16–17 Close the Geometry Loop

Rules 13–15 tell you who is give-way and who is stand-on in overtaking, head-on, and crossing situations. Rules 16 and 17 tell each vessel what to do once that assignment is made. On the ONC06 Master Less Than 100 GRT exam, Q100 Rules of the Road is scored at 90%. Missing the stand-on port-turn prohibition or the staged Rule 17 duties is a classic fail pattern. For a Master of a passenger-carrying vessel — water taxi, dinner cruise, T-boat whale-watch under 100 GRT — these rules are not abstract: passengers expect steady course, but the Rules also demand early give-way action and, when the other vessel freezes, lawful late stand-on action that still avoids a crash.

Rule 16 — Action by Give-Way Vessel

Rule 16 is short and absolute in spirit:

Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear.

Three exam words do almost all the work:

1. Early — act while range still allows a safe, obvious pass; do not wait for close quarters.
2. Substantial — the change must be large enough to be readily apparent (Rule 8(b) language echoes here).
3. Keep well clear — the goal is generous CPA, not a legal-minimum scrape past the other vessel's bow.

Rule 16 does not invent a new maneuver type. It loads the quality standard onto whoever is already give-way under Rules 12–15 or 18. If you are the power-driven vessel with another power-driven vessel on your starboard bow (Rule 15), Rule 16 requires you to take early, substantial action — typically a bold starboard alteration to pass astern, not a late throttle blip or a timid 5° drift.

Master Scenario: Give-Way on a Harbor Crossing

You command an 80-foot inspected passenger vessel on a city harbor loop. A commercial ferry appears on your starboard bow with a steady bearing (Rule 7 risk). You are give-way under Rule 15. Rule 16-correct action: while still well apart, make one early, substantial course and/or speed change that keeps well clear — usually alter to starboard to pass astern, verify until past and clear, and sound required signals. Rule 16-incorrect action: hold course hoping the ferry "moves," cut across her bow at the last minute, or make a succession of tiny trims that never open CPA.

Rule 17 — Action by Stand-On Vessel

Rule 17 is staged. Exam items test which stage you are in.

17(a)(i) — Keep Course and Speed

Where one of two vessels is to keep out of the way, the other shall keep her course and speed. Predictability is the stand-on vessel's first duty. The give-way Master is calculating where you will be; if you wander, accelerate randomly, or "help" with a half-turn too early, you destroy the geometry the give-way vessel needs to clear you safely.

On a passenger boat, "keep course and speed" means hold a steady, known track while the other vessel still has room to act. Q100 answers almost always reward that primary 17(a)(i) duty over random early wandering.

17(a)(ii) — May Take Action Alone

The stand-on vessel may take action to avoid collision by her manoeuvre alone as soon as it becomes apparent that the vessel required to keep out of the way is not taking appropriate action in compliance with the Rules.

This is permission, not yet the mandatory last-second duty. When the give-way vessel is clearly not acting (no course change, no speed reduction, no signal, closing CPA), the stand-on Master is allowed to maneuver alone. Use Rule 8 standards: positive, ample time if still available, readily apparent, check until past and clear.

17(b) — Shall Take Action When Collision Cannot Be Avoided by Give-Way Alone

When, from any cause, the vessel required to keep her course and speed finds herself so close that collision cannot be avoided by the action of the give-way vessel alone, she shall take such action as will best aid to avoid collision.

The verb changes from may to shall. At this range, Rule 2(b) and Rule 17(b) both push you off pure stand-on pride. Slow, stop, reverse, or alter as needed — choose the action that best aids avoidance, not the action that "punishes" the other vessel for being wrong.

17(c) — No Port Alteration for Power-Driven Stand-On (Critical)

A power-driven vessel which takes action in a crossing situation under 17(a)(ii) to avoid collision with another power-driven vessel shall, if the circumstances of the case admit, not alter course to port for a vessel on her own port side.

Why? In a classic crossing, the give-way vessel is on your port side (she has you on her starboard). If she finally wakes up and alters to starboard to pass astern of you — the usual correct move — and you simultaneously alter to port, you both turn into the same water and create a head-on collision from a fixable crossing. The rule therefore forbids that port turn for the power-driven stand-on vessel when circumstances allow any other option.

Memory hook: stand-on power in a crossing — do not turn port toward the give-way vessel on your port side. Prefer starboard, slow, stop, or reverse under 17(a)(ii).

17(d) — Give-Way Not Relieved

Rule 17 does not relieve the give-way vessel of her obligation to keep out of the way.

Rule 16–17 Duty Ladder

Master Scenario: Stand-On Ferry on Your Port Bow

You are Master of a 65-foot passenger vessel on a steady coastal track. Another power-driven tour boat is on your port bow with a steady bearing — you are stand-on; she is give-way. Correct early stage: hold course and speed, watch closely, prepare engines. If it becomes apparent she is not acting, you may act alone under 17(a)(ii) — but do not alter to port toward her if circumstances admit; prefer slow/stop or a starboard option that does not meet her starboard turn. If she is now so close that she alone cannot avoid collision, you shall take the action that best aids avoidance — including Rule 8(e) all-way-off if needed.

Exam Framing for Q100 (90%)

Highest-yield phrases: early and substantial / keep well clear (16); keep course and speed (17(a)(i)); may act when give-way is not acting (17(a)(ii)); shall act when collision cannot be avoided by give-way alone (17(b)); power-driven stand-on shall not alter to port for a vessel on her own port side (17(c)); give-way not relieved (17(d)). Master stems dress these facts in passenger ferries and harbor crossings — the rule language is identical, and the 90% cut leaves no room for mixing may with shall.