Rule 16 in the COLREGs explains when to maintain course and speed to avoid a collision

Rule 16 of the COLREGs isn’t a buzzword you see on a sticker or a quick memorize-and-forget line. It’s a practical principle that keeps boats predictable when they’re on a collision course. In plain terms, Rule 16 says: when you’ve got another vessel coming at you, the vessel that is supposed to keep going—stand-on—must maintain its course and speed unless it becomes obvious the other boat isn’t taking action to avoid a collision. It’s a rule built for clarity in the chaos of open water.

Let me explain why that matters. On a busy stretch of coast or a narrow channel, you’re not just navigating a straight line from point A to point B. You’re coordinating with other vessels that might be moving differently, with different speeds, and in slightly different directions. If both boats suddenly decide to zigzag at the same time, confusion can turn into contact. Rule 16 is designed to reduce that confusion by creating a steady baseline. The stand-on vessel stays the course, and the give-way vessel does the maneuvering—ideally early and decisively enough to prevent a collision.

A simple way to picture it is to imagine you’re driving on a two-lane road with one car in front and another behind. If the car ahead keeps its speed and lane, you know where it’s going. If you notice the car behind isn’t slowing or changing lanes in a safe way, you adjust. The water version isn’t exactly the same, but the logic holds: predictability creates space for safe decisions.

Stand-on versus give-way: who does what, and when

Rule 16 sits next to a handful of other rules that help boats decide who should act. Rule 17 discusses the give-way vessel—this is the vessel that must take early and substantial action to avoid a collision. Rule 18 covers responsibility for crossing vessels, where one party may be the stand-on vessel and the other the give-way vessel depending on the situation.

Here’s the practical bit: as a stand-on vessel, you’re not free to maintain course forever if a collision is inevitable. You’re obliged to keep going straight and steady unless it becomes clear that the other vessel isn’t taking appropriate action to avoid you. In that moment, the responsibility shifts, and you may need to maneuver to prevent an accident. The key phrase you’ll hear on decks around the world is all about predictability—keeping your path steady makes it easier for the other vessel to interpret your intentions quickly.

Why this rule feels so intuitive in the real world

Think about a crowded harbor at dusk, or a fishing boat shifting its gear near a busy channel. It’s tempting to assume, “If I’m not sure, I’ll just adjust a little to be safe.” Except that little adjustment might create a new risk for someone else or even backfire if both boats react the same way. Rule 16 pushes us toward a simple decision: hold your course and speed unless you’re certain the other vessel will not avoid danger. If you’re unsure, it’s safer to err on the side of caution and take timely action yourself.

This approach mirrors good habits on land as well. When cars approach an intersection where the line of sight is limited, drivers hold their lane and speed, trusting others to do the same. If a vehicle looks like it might cross into your path, you don’t hope for a better outcome—you adjust early. The same logic applies at sea, but with a few extra variables like wind, current, and vessel type.

A few real-world flavors to chew on

• Sail versus power: Sailboats have different handling characteristics than motorized vessels. Rule 16 still asks the stand-on vessel to stay on course and speed, but sailors might be more cautious about changing speed or altering course in shifty winds. The motor boat, meanwhile, might have more immediate maneuvering options. The bottom line remains: predictability matters, regardless of what kind of boat you’re on.

• Narrow channels: In tight water, keeping a steady course can be the easiest way to reduce near-m misses. Other vessels can gauge your momentum, judge your path, and act accordingly. If everyone slows or swerves unpredictably, the channel becomes a moving chessboard with too many sudden moves.

• Night operations: Visibility changes everything. Rule 16 is a reminder to stay consistent in your movement, so other boats—perhaps using radar, AIS, or watchful eyes—can anticipate your path even when lights are low.

Practical tips you can carry on deck

• Visualize the stand-on and give-way roles before you even hit the water. If you’re the stand-on vessel in a scenario, ask yourself: “Am I sure the other boat will act in time to avoid me?” If the answer isn’t a confident yes, you may need to act.

• Use early, clear, and decisive actions if danger becomes apparent. A small course adjustment now is better than a large, abrupt one later.

• Communicate when needed. While Rule 16 emphasizes maintaining course and speed, there are situations where reasonable signals or brief visibility of your plan helps reduce uncertainty. A quick radio call or a conspicuous signal can prevent a tense moment from turning into trouble.

• Don’t chase collisions with “will they or won’t they?” Thinking in terms of probabilities is a safety trap. Treat potential risks as real and plan for them.

How Rule 16 sits with other navigation rules

Rule 16 is part of a broader toolkit that guides collision avoidance. It doesn’t stand alone; it interacts with speed guidelines (how fast is safe given the conditions), risk of collision assessments (am I on a collision course or not?), and actions to take to avoid contact (alter course, slow down, stop). The whole framework is about turning a potentially chaotic situation into something you can reason through calmly and quickly.

A quick mental model you can use

If you’re on a collision course with another vessel, ask yourself:

• Who has the stand-on responsibility here? Am I the one expected to maintain course and speed?

• Is there an apparent risk of collision? If yes, what immediate action is required to avoid it?

• Can I communicate my intentions clearly to the other vessel (even if just through light, horn, or radio)?

• Will my action keep both boats safe while maintaining predictable movements?

By keeping this set of questions in mind, Rule 16 stops becoming a dry rulebook item and starts feeling like a practical habit you bring to every on-water decision.

Common misconceptions—and why they trip people up

• “Stand-on means never move.” Not true. Stand-on means you keep your course and speed as long as the other boat is taking appropriate action. If you see clear danger or the other vessel isn’t acting, you’re allowed—and sometimes required—to maneuver.

• “If both boats change course at the same time, we’re safe.” That’s precisely what Rule 16 tries to avoid. Conflicting changes can create new risks. Clear, early, and decisive action is better than a series of last-minute swerves.

• “All vessels can be stand-on in every situation.” In crossing situations or with certain vessel types, the stand-on role may shift. The rules are situational, and staying adaptable matters.

A note on the bigger picture

Rule 16 is a small sentence with a big job: it keeps the water sense-making instead of guesswork. When every vessel moves with a shared sense of predictability, the chances of safe navigation rise. It’s one of those rules that doesn’t sound dramatic, but it quietly does a lot of heavy lifting. It’s about reducing ambiguity, not about flexing a power move.

Where to focus next

• Take a closer look at how Rule 16 interacts with Rules 17 and 18, which spell out the give-way responsibilities and crossing situations. Understanding the full flow helps you see the logic in the order of actions.

• Practice with real-world scenarios. Sit in a harbor or watch videos of near-miss moments and trace who should act and why.

• Stay curious about equipment. Radar, AIS, and proper lookout practices all feed into how confidently you can decide to stay the course or alter it.

The takeaway

Rule 16 is a quiet compass in the storm. It tells you when to hold steady and when to shift gears, all with an eye toward predictability and safety. In the hands of a careful mariner, it turns potentially chaotic moments into manageable decisions. It’s not about being rigid; it’s about being reliable. And in the end, that reliability is what keeps waters safe for everyone who sails them.

If you’re curious to connect Rule 16 to day-to-day boating—the feel of a tide shift, the hum of a crowded harbor, the moment you spot a vessel looming on your horizon—that connection is what makes navigation feel less like a rulebook and more like an practiced craft. After all, learning the COLREGs is really about building a shared sense of how we move through space on the water, together. And that shared sense? It starts with something as simple and essential as maintaining your course and speed when the moment calls for it.