The core rules
- Rule 5 — keep a proper lookout at all times, by sight and by hearing.
- Rule 6 — proceed at a safe speed for the visibility, traffic and conditions.
- Rule 7 — use all available means to decide whether a risk of collision exists; a steady bearing with decreasing range means it does.
- Rules 13-15 — the overtaking vessel keeps clear; head-on, both alter to starboard; crossing, give way to the vessel on your own starboard side.
- Rule 18 — a power-driven vessel gives way to sailing vessels, and to vessels not under command or restricted in their ability to manoeuvre.
| Encounter (power) | Give-way vessel | Action |
|---|---|---|
| Head-on | Both | Each alters to starboard |
| Crossing | Vessel with the other on her starboard side | Alter to starboard; do not cross ahead |
| Overtaking | The overtaking vessel | Keep clear until past and clear |
| The three power-driven encounters. |
Risk of collision
The test for risk of collision is the compass bearing of an approaching vessel: if the bearing stays steady while the range closes, a collision is developing and action is needed. Action should be early, obvious and, in a crossing or head-on meeting, an alteration to starboard. A small, late alteration is dangerous because the other vessel may not notice it in time.
NOTE — Sailing does not always mean right of way A sailing yacht still gives way to a vessel not under command, one restricted in her ability to manoeuvre, and, in a narrow channel, a vessel constrained by her draught. Know Rule 18 in full, not just 'power gives way to sail'.
WARNING — A steady bearing is the warning If the compass bearing of an approaching vessel does not change and the range is closing, you are on a collision course. Do not wait to be sure — take early, clear action.