COLREGs Revision: The Rules MCA Oral Candidates Must Know Well

COLREGs knowledge underpins every MCA oral exam at every level. Whether you are preparing for OOW Unlimited, Chief Mate or Master, examiners will test your understanding of the Collision Regulations — not just your ability to recite rule text, but your capacity to apply the rules correctly in real scenarios under follow-up questioning.

Why COLREGs Matter in the Oral Exam

The International Regulations for Preventing Collisions at Sea (COLREGs) are the legal framework governing how vessels behave to avoid collision. Every deck officer certificate requires candidates to demonstrate thorough knowledge of the regulations. COLREGs questions frequently feature in oral exams because collision avoidance is central to safe navigation, and because the regulations require both knowledge and contextual judgement.

Rule 5 — Lookout

Every vessel must at all times maintain a proper lookout by sight and hearing, as well as by all available means appropriate to the prevailing circumstances and conditions. A proper lookout is not just about having someone on the bridge. It means actively watching and listening, using radar and other equipment, and maintaining situational awareness.

Rule 6 — Safe Speed

Safe speed is contextual, not fixed. It is the speed at which a vessel can take proper and effective action to avoid collision and stop within an appropriate distance. The factors to consider are set out in Rule 6 and include visibility, traffic density, manoeuvrability, background light, sea state, and — when radar is in use — specific radar-related factors including stopping distance and detection limitations.

See our dedicated article: Safe Speed Explained for MCA Oral Exams.

Rule 7 — Risk of Collision

Risk of collision must be assessed using all available means. If there is any doubt, risk shall be deemed to exist. The classic indicator is constant bearing with decreasing range, but candidates must understand that a slowly changing bearing does not necessarily confirm adequate clearance. ARPA data should be interpreted with awareness of its limitations.

Rule 8 — Action to Avoid Collision

Any action taken to avoid collision must be positive, made in ample time, and large enough to be readily apparent to another vessel. Small, hesitant alterations of course or speed are dangerous. A single bold alteration is almost always preferable to a series of small ones. Actions must be assessed to ensure they result in a safe passing distance.

Crossing Situations

In a crossing situation between two power-driven vessels, the vessel which has the other on her starboard side is the give-way vessel and must keep clear. The stand-on vessel must maintain course and speed initially, but if the give-way vessel fails to act, the stand-on vessel may take action — and must act when collision cannot be avoided by the give-way vessel alone.

Head-On Situations

When two power-driven vessels meet on reciprocal or near-reciprocal courses with risk of collision, both shall alter course to starboard so each will pass on the port side of the other. In doubt about whether a head-on situation exists, the vessel must assume that it does and act accordingly.

Overtaking

Any vessel overtaking another must keep clear of the vessel being overtaken. A vessel is overtaking if it is approaching another from a direction more than 22.5 degrees abaft her beam. The overtaking obligation continues until the vessels are finally past and clear — even if the overtaking vessel subsequently becomes a crossing vessel.

Restricted Visibility

In or near an area of restricted visibility, every vessel must proceed at a safe speed, have engines ready for immediate manoeuvre, have a proper lookout, and navigate with extreme caution. Vessels must use radar and sound appropriate fog signals. If risk of collision exists through radar alone, avoid alteration of course to port for a vessel forward of the beam (other than for an overtaking vessel).

Lights and Shapes

Navigation lights must be exhibited from sunset to sunrise and in restricted visibility. Candidates must be able to identify the lights displayed by different vessel types, understand the significance of lights and shapes, and explain what they indicate about a vessel's status and activities.

Sound Signals

Sound signals serve two purposes: manoeuvring signals in sight of another vessel, and fog signals in restricted visibility. Candidates must know the standard manoeuvring signals and the fog signals required for different vessel types and conditions.

How to Revise COLREGs Effectively

Effective COLREGs revision goes beyond reading the rules. Use scenario-based practice to apply the rules to real situations. Practise explaining the reasoning behind each rule — why does the give-way vessel have that obligation? What is the logic behind altering to starboard? Understanding the reasoning makes the rules far easier to apply and explain under questioning.