Boats have no brakes and no lanes, so the sea has rules. Learn what the lights say at night, who gives way, what the horn means and how the buoys guide you. Then play the right-of-way game.
The idea behind every rule
The rules exist so that two boats never need to argue. In every meeting, one boat is the give-way vessel and keeps clear early and clearly. The other is the stand-on vessel and holds its course and speed. If the other boat does not give way, you still act in time. Nobody wins by being right in a collision.
A friendly first look, not the law book
This lesson teaches the basics of the international collision rules (COLREGs) in plain words. Before you go out on your own, read the full rules and the local rules where you sail. Buoy colours also differ by region: this lesson uses region A (Europe, Africa, Australia and most of Asia). Region B (the Americas, Japan, Korea and the Philippines) swaps red and green.
Who gives way?
You are the blue boat. Look at the other boat and decide what you do. Ten situations, shuffled every time.
A boat at night, seen from above, heading up
Three meetings
Who gives way to whom: the arrow points up, toward the boats you give way to
Horn signals: dots are short blasts, the bar is a long one
Buoys in region A
A danger in the middle, and the four cardinal marks around it
Study sheet
All the words in one place, by level.
Level 1: Lights at night
Port light (red)
The red light on the left side of the boat. It shines from straight ahead round to just behind the left side. If you see a red light, the other boat is crossing from your right, so you give way. Red means stop and let it pass.
Starboard light (green)
The green light on the right side of the boat. If you see a green light, the other boat is on your left and you keep your course. Green means go, you stand on.
Masthead light
A white light high on the boat, shining forward over 225 degrees. A boat under engine shows it. A sailboat under sail alone does not, so seeing one means the boat is using its engine.
Stern light (white)
A white light at the back, shining 135 degrees backward. If you only see a white light, you are looking at the back of a boat, and you are probably catching up with it.
Level 2: Meeting boats
Head-on
Two boats coming straight at each other. Neither is the stand-on boat: both turn to starboard (right) early and clearly, and pass port side to port side.
Crossing
Two boats whose paths cross. The boat that has the other on its right (starboard) side gives way. If you can, do not cross in front of the other boat.
Overtaking
Coming up from behind a slower boat. The overtaking boat always keeps clear, whatever kind of boat it is, until it is completely past and clear.
Give-way vessel
The boat that must keep out of the way. It acts early, with a big change of course or speed, so the other boat can see what it is doing.
Stand-on vessel
The boat that keeps its course and speed so the other boat can plan. If the give-way boat does not act, the stand-on boat must act in time to avoid a collision.
Level 3: The pecking order
Not under command
A boat that cannot manoeuvre because of an exceptional breakdown, such as engine or steering failure. Everyone else keeps clear. By day it shows two black balls, one above the other. At night, two red lights.
Restricted in ability to manoeuvre
A boat whose work stops it from turning aside, for example a dredger, a cable layer or a boat towing. By day it shows ball, diamond, ball. At night, red, white, red lights.
Fishing vessel
A boat with nets, lines or trawls out that limit how it can steer. By day it shows two cones with their points together, like an hourglass. At night, green over white lights.
Sailing vessel
A boat moving by sail alone. It gives way to the three boats above it, and to a boat it is overtaking. If it also runs its engine, it counts as a power-driven vessel.
Power-driven vessel
Any boat moving under engine, including a sailboat with the engine on. It gives way to every boat above it in the ladder.
Level 4: Sound signals
One short blast
"I am turning to starboard (right)." A short blast lasts about one second.
Two short blasts
"I am turning to port (left)."
Three short blasts
"My engine is going astern (in reverse)."
Five or more short blasts
The danger signal. "I do not understand what you are doing" or "I think you are about to hit me." Used when you doubt the other boat's intentions.
One long blast
A prolonged blast lasts four to six seconds. A power boat making way in fog sounds one every two minutes. It is also used when coming up to a bend or a spot where other boats may be hidden from view.
Level 5: Buoys that guide you
Port-hand mark (red)
A red can-shaped buoy. Coming in from the sea, in region A, it marks the left (port) side of the channel and you keep it on your left. In region B, the colours are swapped.
Starboard-hand mark (green)
A green cone-shaped buoy. Coming in from the sea, in region A, it marks the right (starboard) side of the channel and you keep it on your right.
Safe water mark
Red and white stripes with a red ball on top. There is safe water all around it. It often marks the middle of a channel or where you first reach the coast.
Isolated danger mark
Black with a red band and two black balls. It sits right on top of a small danger, such as a wreck or a rock. There is water all around it, but keep a good distance.
Special mark (yellow)
A yellow buoy, often with an X on top. It is not for finding your way. It marks things like cables, pipelines, anchoring limits, race marks or swimming areas.
Level 6: Cardinal marks
North cardinal mark
Black over yellow, with two cones both pointing up. The safe water is to the north of it, so you pass on its north side. The danger is south of it.
East cardinal mark
Black, yellow, black, with two cones base to base, like a diamond. The safe water is to the east of it.
South cardinal mark
Yellow over black, with two cones both pointing down. The safe water is to the south of it.
West cardinal mark
Yellow, black, yellow, with two cones point to point, like an hourglass or a wine glass. The safe water is to the west of it.