Rule 22 explains signals for vessels engaged in specific activities at night or in reduced visibility

Rule 22: What it really signals on the water

If you’ve ever watched a boat at night and wondered what its lights and shapes were trying to tell you, you’ve touched the heartbeat of Rule 22. In the world of COLREGs, this rule is all about signaling when a vessel is doing something specific. Not just cruising along, but actively engaged in an activity that other mariners need to notice and respect. In short: Rule 22 defines signals for vessels engaged in particular activities, especially when visibility is low.

Rule 22 at a glance: signals, not secrets

Let me explain it plainly. Rule 22 lays out the shapes and lights that a vessel must display to signal its current activity or status. Think of it as a language the sea uses to keep conversations clear, even when the weather is murky or when it’s dark outside. The signals aren’t random flair; they’re precise cues that let other ships know what that vessel is up to. Examples you’ll hear about include vessels that are anchored, those that are constrained by their draft, and vessels that are fishing. Each activity has its own visual cue, designed to prevent misunderstandings and, above all, collisions.

Why this matters more than you might think

The night sea is a tricky place. Even a small misunderstanding can lead to a near-miss, especially when vessels are close and speeds vary. Rule 22 isn’t just a rule; it’s a safety net. By signaling clearly, a ship communicates intent and status—so nearby boats can adjust course, slow down, or give way as needed. It’s a practical dance of visibility and anticipation. And because so much of this signaling happens in the dark or in fog, the shapes and lights become a kind of universal vocabulary that mariners share across languages and regions.

What counts as “specific activities” under Rule 22

Here’s where the rule gets tangible. The “specific activities” typically highlighted under Rule 22 include:

• At anchor: A vessel showing the standard day shapes and lights that indicate it is anchored. The signals tell others that the ship isn’t just drifting or cruising; it’s literally tethered to a spot on the water.

• Constrained by its draft: Some vessels can’t move freely due to their depth in the water. The signaling for these ships communicates that their ability to maneuver is limited by how much water they require to sit safely in depth.

• Engaged in fishing: Fishing vessels have their own distinctive signals. They indicate that workers are actively setting, hauling, or tending gear. This is important because fishing gear and lines can present hazards to other approaching vessels.

You don’t need to memorize every possible shape or light to feel the thread of Rule 22. The point is to recognize that different activities have dedicated, recognizable signals so other mariners can react appropriately.

How signaling works in practice: lights and shapes in action

The practical takeaway is simple: if you’re navigating and you spot a vessel displaying certain lights or shapes, you adjust your behavior accordingly. The rule uses both day shapes (visible on deck during daylight) and night signals (lights or shapes that are visible in the dark). When you’re learning or sailing, here’s what to keep in mind:

• Visual cues are time-sensitive. A signal’s meaning is tied to the vessel’s current activity, not to its past or future plans. Be alert to changes in signals as a vessel switches activities.

• Lights tell you more about speed and intent. A vessel that’s anchored will typically show a white light, and its position at night is predictable. A fishing vessel’s signaling may include specific configurations that warn nearby traffic to stay clear of nets and gear.

• Shapes deliver quick, at-a-glance information. Day shapes are handy for brief, non-visual communication situations. In mixed lighting or fog, lights take precedence, but the shapes still guide your understanding when you can see them.

A few scenes you might imagine

• The anchored freight barge drifts no more than a few inches, a quiet light glows on its bow, and a simple white beacon marks its quiet station. You pass by, knowing you should keep a safe distance and avoid cutting across its stern wake.

• A fishing vessel edges slowly along a coastline, nets out or being stowed, using the standard signals that say, “I’m working here—give me space.” You ease your speed and plan a wider arc around it, especially if the wind pushes you both toward busy channels.

• A sizable tugboat, temporarily restricted by depth, carries a signal that says, “I can’t maneuver freely right now.” You adjust your course sooner rather than later, saving fuel, time, and nerves.

Connecting the dots: Rule 22 in the larger rulebook

Rule 22 doesn’t stand alone. It sits within a framework where lights, shapes, and general responsibilities create a predictable order on the water. While Rule 15 (look-out) and Rule 17 (risk of collision) push for awareness and proper actions, Rule 22 gives you the exact signals to interpret when a vessel isn’t just cruising but actively doing something that requires attention from others.

For the navigator, this means developing a habit: scan for signals early, interpret what they’re saying, and adjust your plan. It’s as much about reading a situation as it is about following a rule. The sea rewards the attentive—those who notice a faint light over the horizon, or a deck shape that pops into view as you close distance in fog.

Practical tips to stay ahead of the signal game

• Keep your eyes moving, not just in front. Look for a combination of lights and shapes, not only one cue. A vessel may present a white light plus a distinctive day shape in daylight.

• Remember constraints aren’t personal. If a ship is constrained by its draft, it’s not being stubborn—it’s limited by physics. Give it room to maneuver and plan your pass accordingly.

• Use speed as a communication tool. Slowing down when you see a signaling vessel is often the simplest, safest reply. Speed changes can prevent close-quarters surprises.

• Don’t rely on guesswork. If you’re unsure what a signal means, reduce speed and increase your watch. Better to be cautious than to learn a hard lesson.

• Practice situational awareness in varying light. Dusk or early dawn can flip a signal’s visibility. Be prepared for signals to be harder to pick up when the lighting is fickle.

A quick checklist for signals that shout “pay attention”

• Are there day shapes indicating activity? If so, what is the vessel doing? Anchorage, fishing, or other work?

• Which lights are visible, and do they align with the vessel’s stated activity?

• Is there any sign that the vessel might be changing its status? Signals can switch as work shifts and weather changes.

• How far away is the vessel, and what is your current course and speed? Adjust your plan to maintain safe separation.

Keep the big picture in mind

Rule 22 isn’t about memorizing a shelf full of trivia; it’s about a practical, shared vocabulary at sea. It’s the kind of knowledge that quietly saves time, fuel, and nerves when you’re out on the water at night or in mist. It’s also a reminder that navigation is as much about communication as it is about propulsion and steering.

If you’re studying this stuff for personal growth or a professional milestone, think of Rule 22 as a window into maritime courtesy. The signals aren’t just rules; they’re a way to show respect for other crews who may be working, fishing, docking, or steaming through a busy channel. Respecting those signals keeps everyone safer and moving smoothly.

A few reflective thoughts

• Sometimes the simplest signals carry the most weight. A single light or a basic shape can tell you more about a vessel’s intent than a long radio transmission.

• Signals can change with the conditions. A vessel signaling one thing in good visibility might have to modify its signaling if fog rolls in or rain sharpens the night into a blur.

• It’s okay to be cautious. If you’re unsure what a signal means, slow down, increase watch, and give the other vessel a generous margin. The sea forgives careful behavior.

In closing: listen to the sea’s signals

Rule 22 may sound technical, but its spirit is human: it’s about clear communication when watchers are in the dark. The better you understand these signals, the more naturally safe your time on the water feels. It’s like learning a new language—one that keeps you connected to every other mariner who relies on the same rules to keep the voyage steady.

If you’re out there, eyes peeled and mind alert, you’ll notice the quiet choreography of lights and shapes. It’s not magic; it’s math, weather, and a touch of patience. And when you learn to read Rule 22 with ease, you’re not just following a rule—you’re participating in a long tradition of safe, respectful seamanship.