Safe Operation and Navigation Rules
What this domain tests
This domain covers the Collision Regulations and safe navigation practice: rights of way, sound and light signals, speed and lookout, and safe passage in channels. Questions often present two vessels and ask who gives way, or ask what a specific light or sound means.
Steering and sailing rules
- Power-driven vessels give way to sailing vessels, except where the sailing vessel is overtaking or is a vessel not under command.
- When two power-driven vessels meet head-on, both alter course to starboard and pass port-to-port.
- Crossing: the vessel with the other on its starboard side gives way; the stand-on vessel keeps course and speed but must act if collision is imminent.
- Overtaking: the overtaking vessel keeps clear regardless of propulsion type.
- Keep a proper lookout by sight and hearing, maintain a safe speed for visibility and traffic, and use all available means to determine risk of collision.
Lights and shapes
- Power-driven vessels under way show sidelights, a sternlight, and a masthead light (two masthead lights if 50 m or more).
- Sailing vessels under way show sidelights and a sternlight; a vessel under oar or paddle shows a white light or lantern in time to prevent collision.
- Anchored vessels show an all-round white light where required.
- Day shapes: a black ball for anchoring, a cone point-down for a sailing vessel motor-sailing.
Sound signals
- One short blast: altering course to starboard. Two short: to port. Three short: operating astern propulsion.
- Five or more short rapid blasts: danger or doubt about the other vessel's intentions.
- In restricted visibility, power-driven vessels make one prolonged blast at intervals of not more than two minutes.
Worked example
A powerboat approaches a sailboat from the sailboat's port side, and the sailboat is under sail only. Reasoning: the powerboat is the give-way vessel because a power-driven vessel keeps clear of a sailing vessel, and the geometry also places the sailboat on the powerboat's starboard side. The powerboat should alter course to pass astern; the sailboat holds course and speed unless risk becomes imminent.
Traps that cost marks
- Applying the sailboat rule when the sailboat is overtaking; the overtaking vessel always gives way.
- Reversing the crossing rule and treating the give-way vessel as stand-on.
- Forgetting that the stand-on vessel must still act to avoid collision.
- Mixing up one and two short blasts.
Key points to memorize
- Overtaking vessel always keeps clear.
- Head-on power vessels pass port-to-port.
- Crossing: vessel with the other on its starboard side gives way.
- One short blast means altering to starboard; five short means danger.
- Keep a proper lookout and a safe speed at all times.