You are the stand-on vessel in a crossing situation. The give-way vessel is not taking action. At what point and how do you act under COLREGs Rules 16 and 17?

A. Rule 17 stand-on obligations: (a)(i) — maintain course and speed initially; (a)(ii) — when it becomes apparent the give-way vessel is NOT taking appropriate action, the stand-on vessel MAY take action to avoid collision by her manoeuvre alone; (b) — when a collision cannot be avoided by the give-way vessel alone, the stand-on vessel SHALL take action. The timing sequence: (1) Initially: maintain course and speed — Rule 17(a)(i); (2) Give-way not acting, situation developing: you MAY act to help (Rule 17(a)(ii)) — but only by altering to starboard (not to port for a vessel on your port side, as this creates confusion); (3) Imminent collision, no action possible by give-way alone: you MUST act — Rule 17(b). Sound signal Rule 34(d): if in doubt about another vessel's intentions, give at least 5 short blasts on the whistle immediately.

B. The stand-on vessel must maintain course and speed at all times until the give-way vessel passes. Taking any action while stand-on is a COLREGs violation that transfers fault to the stand-on vessel.

C. Rule 17 allows the stand-on vessel to take any action at any time, including altering to port, as long as it increases CPA.

D. The stand-on vessel must contact the give-way vessel on VHF and obtain agreement before taking any avoiding action under Rule 17.

A. Rule 18 establishes the hierarchy for power-driven vessels underway. In order of priority (highest first — you must give way to all of these in this order): 1st — NUC (not under command): cannot manoeuvre, ultimate priority — Rule 18(a)(i); 2nd — RAM (restricted in ability to manoeuvre): limited manoeuvring ability — Rule 18(a)(ii); 3rd — CBD (constrained by draught): cannot deviate from channel — Rule 18(a)(iii) [note: CBD is optional display — not all CBD vessels show the signal]; 4th — FISHING (engaged in fishing with gear): Rule 18(a)(iv) — note this means fishing with nets/lines, NOT a vessel that has fishing equipment on board but is not actually fishing; 5th — SAILING VESSEL: Rule 18(a)(v) — power gives way to sail (with exceptions in Rule 18(b) where a sailing vessel overtaking a power-driven vessel must keep clear). You must keep out of the way of all five in this order.

B. Sailing vessels have the highest priority under Rule 18 as they cannot manoeuvre under power. All other vessels must give way to sailing vessels in all circumstances.

C. Rule 18 applies only when vessels are on a collision course. When vessels are not in a close-quarters situation, the hierarchy does not apply and normal right-of-way rules (Rules 12-17) govern.

D. CBD vessels have the highest priority because they physically cannot change course. NUC vessels can use their anchors or emergency steering, so they rank lower than CBD.

A. Rule 8 — Action to Avoid Collision — requires that avoiding action: (a) shall be taken in ample time (early); (b) shall be large enough to be readily apparent to the other vessel (substantial — a small course alteration of 5-10° may not be seen on the other vessel's radar and does not clearly communicate intent); (c) shall not result in another close-quarters situation; (d) if sea room permits, an alteration of course alone (preferred as most visible from the other vessel); (e) when altering course: the alteration must be large enough to result in a safe passing distance by a wide margin — a sequence of small alterations is discouraged. At 8 minutes TCPA with CPA 0.3nm: act NOW — do not wait for CPA to reduce further. Alter course substantially to STARBOARD (for a crossing situation where the vessel is on your starboard side and you must keep clear under Rule 15). Verify by radar that the action is effective.

B. Under Rule 8, any alteration that increases CPA is valid, including small alterations of 5°. The OOW has discretion on the size of alteration required.

C. Rule 8 requires the give-way vessel to stop engines first, then alter course once the vessel has lost headway. Manoeuvring at full speed is prohibited when within 10nm of another vessel.

D. Rule 8 allows VHF agreement as a substitute for a physical manoeuvre. If both vessels agree on passing arrangements by radio, no alteration of course is required.