COLREGS made simple
Including some bits you weren’t taught elsewhere
To begin…
Your primary obligation is the safety of your vessel and the people aboard, followed closely by the obligation to avoid any collision. (Rule 2)
Thus, you must always keep a proper look-out to detect potential hazards. (Rule 5)
You must also travel at a safe speed, appropriate for conditions, that allows stopping in time. (Rule 6)
This deck is intended to help you understand the general framework of the steering and sailing rules.
A sailing yacht and a kayak meet…
You’re the skipper of a 40 foot yacht, gliding down a narrow, dredged channel towards your marina. Ahead of you a kayaker is paddling. What do you do? What should they do?
You’re a kayaker, in the middle of San Francisco Bay, crossing from Angel Island to Berkeley. You spot a large sailing yacht approaching on your right. What do you do? What should they do?
You may have guessed that different circumstances call for different actions, even though in both cases the sailing vessel is far faster than the kayak and has almost 100x the mass.
This is why we’ll begin with Rule 9: Narrow Channels.
As an aside, the COLREGs are mostly silent on human-powered vessels. The US Coast Guard’s take is that “ultimately, the issue of whether a vessel under oars is the give-way or stand-on vessel would fall to what would be required by the ordinary practice of seamen, or by the special circumstances of the case (Rule 2), and, the notion that they are less able than most other vessels.”
Why start with Rule 9?
Many encounters recreational boaters have with large ships fall under Rule 9, which overrides some of the other rules about who is stand-on versus give-way.
Not being aware of this, people often make up various rules to explain what they see. But….
Sometimes local rules, such as harbor by-laws or state law, grant priority to commercial vessels. These apply only in local waters, so it’s important to be aware of the local regulations in your area.
Rule 9: Narrow Channels
As a recreational boater, you are most likely to encounter large shipping traffic in areas where Rule 9 applies. This includes large bays such as San Francisco Bay or Chesapeake Bay.
Loosely summarized, Rule 9 requires you to:
Traffic separation zones (Rule 10) are treated similarly; with the addition that you should only cross them if you must, and when doing so, keep you heading at right-angles to the lane.
Risk of collision, and who goes first
To determine risk of collision, the gold standard is to take a compass bearing on the other vessel. If it doesn’t significantly change, and you’re getting closer, you will collide!
Be wary of using a feature on your own vessel, or a nearby landmark in place of a compass bearing; any yawing or gradual deviation in course will make the former fail, and nearby landmarks will also change in bearing. Very distant marks on the horizon (mountains, stars) are OK for quick, one-off assessments.
When two vessels are converging, one or both will be the “give-way” vessel. That vessel must “take early and substantial action to keep well clear”. (Rule 16) The other must maintain her course and speed. Think of this as “keep doing whatever you’re doing”; if your course bends to follow a river, then continue to follow the river.
A common factor in many collisions is 1) an inadequate look-out, and 2) waiting too long to act.
Why not just give-way to everyone?
The stand-on / give-way rules clarify who must make the first move, to reduce the chance of both vessels attempting to both dodge in the same direction (think of the “sidewalk shuffle” or the “footpath foxtrot”). This is one reason “always giving way” can still be dangerous.
This doesn’t mean you are not allowed to move. When you are the stand-on vessel, keep the timeline below in mind. The precise times and distances depend on the vessels involved: two sailing dinghies need far less space than two container ships.
Time needed for own evasive maneuvers to work
Time needed to sound a warning and see response
Time to allow give-way vessel to maneuver
Time needed to assess the situation and identify roles
Rule 17: Action by Stand-on Vessel
The stand-on vessel has three sequential responsibilities when risk of collision arises:
The timeline below is a rough illustration of how those stages map to collision avoidance.
Note: If you are a power vessel, avoid turning to port if possible. (Rule 17)
Time needed for own evasive maneuvers to work
Time needed to sound a warning and see response
Time watching for give-way vessel to maneuver
Time needed to assess the situation and identify roles
must hold course
may take action
must take action
When operating under power…
Give way to any vessels you are overtaking. (Rule 13)
When meeting head-on, both vessels must alter to starboard. (Rule 14)
Treat crossing situations like all-way stops on land: give way to the vessel to starboard. Do not pass in front of the other if you can avoid it. (Rule 15)
A
B
A
B
To the left, both A & B must divert to starboard.
To the right, B must give way to A
When operating under sail..
Give way to any vessels (sail or power) you are overtaking. (Rule 13)
Know which tack you are on. Vessels with the wind on their port side give way to those on a starboard tack. If both are on the same tack, the vessel to windward gives way. (Rule 12)
If you are motor-sailing, you are not under sail. (Rule 3)
wind
A
B
A
B
In both examples, vessel B is the give-way vessel.
To the left, B is on port tack.
To the right, both are on the same tack, but B is to windward.
What if a sailing vessel meets a power-driven vessel?
Rule 18 defines stand-on and give way relationships between vessels in certain circumstances.
These circumstances have very specific definitions (Rule 3) and, apart from vessels under sail, it can be rare to encounter them. Just because a vessel is very large, or has a fishing line over the side, does not mean it can claim special status.
Anyone higher in the priority list than a sailing vessel must display specific day shapes and lights to indicate that status.
Gives way to…
Gives way to…
Gives way to…
Gives way to…
or
Sailing
Power
Fishing
CBD
NUC
RAM
A sailing yacht and a container ship meet…
Remember the kayak at the start of this deck? A sailing yacht is even smaller compared to a massive container ship.
In confined waters the ship can not easily change course, and so the yacht must be careful to stay well clear. But in open waters, the yacht is slow and has very little control over the crossing. Her safety lies in being seen, and communicating early when there is uncertainty.
A large ship will ideally sight the yacht miles away, and have adjusted course well before the yacht has taken notice. If the yacht panics and changes direction early, this can undo that work and move the yacht back into danger. The yacht skipper may even wonder “why does that ship keep aiming for me?”
Wrapping up…
This deck doesn’t go into the specifics of each rule or the differences between the International Rules and the US Inland Rules. The main purpose of this deck is to get you started on a solid footing.
You can find the complete rules here: https://www.navcen.uscg.gov/navigation-rules-amalgamated
You may have additional questions. Many do, and there are always special cases that keep admiralty courts in business. I’ve listed some texts below, but remember these mainly cover large ships, and do watch the prices!