COLREGS: The Rules of the Road, Simplified

Rule 14 (head-on) requires both vessels to alter course to starboard, passing port side to port side: the nautical equivalent of keeping to the right.

Rule 15 (crossing): the vessel that has the other on her own starboard side is the give-way vessel and must avoid crossing ahead of her, typically by turning to starboard to pass astern.

Rule 13 overrides the sail/power and crossing rules: an overtaking vessel keeps clear of the vessel being overtaken until finally past and clear: even a sailing vessel overtaking a power vessel must give way.

Rule 18 sets the general pecking order: power gives way to sail (among other categories). But this flips the moment the sailing vessel is overtaking, or if the power vessel is a large ship constrained by her draft, fishing, or not under command: those outrank a vessel under sail.

Rule 17 lets the stand-on vessel act as soon as it's apparent the give-way vessel isn't taking appropriate action, and requires it once collision can't otherwise be avoided by the give-way vessel alone. Right of way is not a right to be run down.

Rule 34's manoeuvring signals: one short blast = altering course to starboard, two short blasts = altering to port, three short blasts = operating astern propulsion.

Rule 35 requires a power vessel underway and making way to sound one prolonged blast (4-6 seconds) at intervals of not more than two minutes: this is one of the most-tested COLREGS sound signals.

Rule 9 and Rule 18 both push in the same direction here: vessels constrained by draft to a narrow channel, and vessels under 20m or sailing vessels generally, must not impede a vessel that can only safely navigate within that channel. Being 'right' doesn't help if she physically cannot turn.

Rule 12(a)(i): between two sailing vessels on different tacks, the vessel on port tack keeps clear of the vessel on starboard tack: the classic "port gives way to starboard" rule sailors learn first.

Rule 12(a)(ii): on the same tack, the vessel to windward keeps clear of the vessel to leeward: the leeward boat has less room to manoeuvre without the other's wind shadow, so she holds her course.

Rule 19(d) specifically warns against altering course to port for a vessel forward of the beam (other than one you're overtaking) in restricted visibility: a turn to starboard or a reduction in speed is the safer default.

Rule 27's day shapes mirror her night lights: ball-diamond-ball in a vertical line signals "restricted in ability to manoeuvre" to anyone who can see her silhouette but not her lights.

Annex IV's list includes rockets and flares, continuous fog-signal sounding, "Mayday" by radio, orange smoke, and slowly, repeatedly raising and lowering outstretched arms, a signal you can give with nothing but your own body if you have no other means aboard.

Rule 9(b) specifically names vessels under 20m, sailing vessels, and fishing vessels as ones that must not impede a vessel that can only navigate safely within a narrow channel: the ship's lack of room to manoeuvre takes priority.

Rule 3(h) and Rule 28 define this status for a power-driven vessel whose draft, given the depth of water available, severely restricts her ability to deviate from her course: she needs the deep water she's in and can't simply turn aside.

A loaded ship in a channel may have no room to turn and takes a long distance to slow down, whatever the rulebook says about right of way. The safe habit is early, decisive action that removes any doubt about your intentions.

Rule 6 lists specific factors (visibility, traffic density, manoeuvrability, night, and radar characteristics among them) precisely because "safe" isn't a fixed number; it changes with conditions every single time.

A constant bearing with decreasing range means both vessels are converging on the same point: exactly the situation Rule 7 wants you to catch early, before it becomes a close-quarters problem.

A small, late, or ambiguous course change can be misread or missed entirely: Rule 8 specifically wants your intentions to be unmistakable to a vessel watching from a distance, without needing radio contact.

Crossing at right angles gets you across the lane, and out of the way of vessels using it as intended, in the shortest possible time: an oblique crossing lingers in the lane far longer than it needs to.

Joining at a shallow angle blends you smoothly into traffic already established in the lane; the right-angle rule is specifically for crossing the lane, not for merging into it.

The core restriction is about ambiguity, not volume or duration: a signal that could be read as a distress call or another rule-defined signal risks causing exactly the alarm or confusion you were trying to avoid.

A pilot vessel's manoeuvring is often unpredictable by design (she may need to close alongside a ship at short notice), so recognizing the white-over-red signal and giving her space beats treating her as a routine power vessel.

Unlike a vessel that's merely anchored, an aground vessel is sitting on the bottom, which usually means there's less water than the chart led you to expect nearby, worth respecting rather than passing close.