The animated rules library

When boats are on opposite tacks, the port-tack boat keeps clear of the starboard-tack boat.

Port/starboard applies downwind too — the port-gybe boat keeps clear of the starboard-gybe boat.

When boats are on the same tack and overlapped, the windward boat keeps clear of the leeward boat.

When boats are on the same tack and not overlapped, the boat clear astern keeps clear of the boat clear ahead.

After passing head to wind, a tacking boat keeps clear of others until it is on a close-hauled course.

When two boats are tacking at the same time, the one on the other's port side keeps clear.

The right-of-way rules apply right up to the finishing line — port still keeps clear of starboard.

At a pin-end start, the leeward boat can luff to hold windward boats out of the pin — windward keeps clear, with no proper-course limit before the start.

A boat overlapped in the middle of a stack at the start is trapped — she must keep clear of the boat to leeward, can't escape to windward, and has no proper-course protection before the gun.

A boat must avoid contact with another if reasonably possible — even when it has right of way.

Port fails to keep clear and the boats collide with damage — the port boat breaks rule 10, and the starboard boat is not exonerated under rule 14 if she could have avoided it.

When a boat acquires right of way, it must at first give the other boat room to keep clear.

When a right-of-way boat changes course, it must give the other boat room to keep clear.

A leeward boat that got its overlap from clear astern (within two lengths) may not sail above its proper course.

Rolling up to leeward from clear astern on a run, the new leeward boat has right of way but may not sail above her proper course.

At a mark, an outside boat must give the inside overlapped boat room to round it.

Overlapped boats rounding a windward mark: the inside boat is entitled to room to round.

Clear ahead up the layline at the zone, the leader gets mark-room at the windward mark — a chaser's late dive inside earns nothing.

When a boat is clear ahead as she reaches the zone, the boat clear astern must give her mark-room — a late dive inside earns nothing.

A boat that was clear astern at the zone gets no mark-room from an inside overlap she obtains only after entering the zone.

An outside boat overlapped at the zone still owes mark-room even if the overlap later breaks before the mark.

An inside overlapped boat that must gybe at the mark may sail no farther from it than needed — no swinging wide to set up the gybe.

A boat that tacks from port to starboard in the zone gets no mark-room from a starboard boat fetching the mark — and must not make her sail above close-hauled.

Rule 18 does not apply between boats on opposite tacks on a beat — a port-tack boat at the windward mark gets no mark-room and must keep clear.

When boats pass an obstruction on the same side, the outside boat gives the inside overlapped boat room to pass between it and the obstruction.

A boat needing to tack to avoid an obstruction may hail for room; the hailed boat must respond by tacking or by replying 'You tack'.

At a starting mark, rule 18 is switched off — a windward boat has no right to room to barge in.

In the last minute under a Z, U or black flag, a boat on the course side inside the start triangle is penalised — 20%, DSQ, or DSQ even after a recall.

A boat that touches a mark must take a One-Turn Penalty (one tack and one gybe) once clear of other boats.

The committee boat and pin are starting marks — touch one and you owe a One-Turn Penalty.

Lunging your body forward and stopping abruptly to jerk the boat ahead — ooching — is prohibited propulsion.

A boat that breaks a Part 2 rule can exonerate herself by getting clear and making two full circles — two tacks and two gybes.

Port vs starboard beat to a windward mark on a square line — twist the wind or add a timed shift and the symmetry breaks.

On a pin-favoured line, the boat off the favoured end reaches the windward mark first. The gap is the advantage.

Tacking on the layline lays the mark; tacking late overstands and sails extra distance.

Same distance to windward, but each extra tack loses ground — the 3-tack boat arrives behind.

A single right shift lifts the starboard boat toward the mark and heads the port boat away.

Headed on port? Tack. The boat that tacks onto the lifted tack reaches the mark; the one that holds sails away.

When the committee end is upwind, the boat starting there reaches the mark first.

Slow in the dirty air of two boats ahead, with nobody behind — the simplest fix is to tack onto the other side into clean air.

When a single tack only swaps one boat's shadow for another's, tack twice to shift across into a clean lane on the same tack.

Stuck in bad air but boxed in — boats on your tail mean a tack would land on them. Put the bow down, foot for speed, and slide into the clean lane to leeward.

Same dirty air as the pinned case, but the boat behind is far enough back that you can tack onto port and cross cleanly into clean air.