The illustration below shows the deck plan of a vessel with the various parts as they are named.

A vessel must always be navigated on the starboard side (right) of a river
or channel - Pass Port to Port...(left)

Keep well to the right of mid channel whenever practicable. Approaching a bend or curve that obscures visibility a powerboat must signal with one long blast of its horn... Any boat approaching from the other side must answer with a similar blast.

Each boat alters course to starboard (right) and passes port to port (left).

This rule applies to narrow channels but can also be applied in open water if there is doubt of the other boat's intentions... a single, short whistle blast signals this manoeuvre; giving a similar short blast is the proper response of assent.

Vessels under power passing starboard to starboard with adequate clearance

Sometimes in a meeting situation, such as when two boats are approaching starboard bow to starboard bow, but far enough apart so there is no danger of collision, they can legally pass each other starboard to starboard.

Each acknowledges the situation and intent with two short blasts.

Power usually gives way to sail. However, this does not always apply. Larger power-driven boats with limited manoeuvrability should be given a wide berth by all boats... a sailboat under auxiliary power also loses its privilege...even if the sailboat's canvas is hoisted.

The boat on starboard tack has right-of-way over the boat on port tack.

The leeward boat has right-of-way over the windward boat.

When two close-hauled sailboats converge... starboard tack always has right of way. The boat on the port tack (i.e., with the wind coming over its port side) must stay clear - by turning to pass astern of the other (below), by tacking onto a new course or by luffing up until the other has passed by.

Starboard tack also has right of way when two sailboats running before the wind on opposite tacks are converging on the same point. However, should one boat approach another from behind, it then is overtaking and must keep out of the other's way regardless of which tack it is sailing on.

When two boats are sailing along side by side on the same tack, the boat to leeward - the one farthest from the source of the wind - has the right of way. The boat on the windward side must avoid bearing down on the other, even if that means luffing up or coming about to the other tack to keep clear.

A boat moving in a channel - or fairway - normally has the right of way over all boats leaving a dock or berth. The docked powerboat shown below must give 3 short whistle blasts before backing - and must stop if the boat in the fairway warns of a collision by sounding four or more short blasts.

A ferryboat is the only vessel that enjoys the right of way when docking or moving out into the fairway. Though no formal regulation specifies this privilege, the ferry's inherent need to embark and dock repeatedly and on schedule has resulted in a tacit agreement among seamen to give ferries the right of way.