Anchored vessels must repeat their sound signal every minute under COLREGs Rule 35.

Signals on the water aren’t just noise; they’re the maritime version of a handshake. When you’re out in a busy harbor or cruising along at night, sound signals carry more meaning than you might guess. They tell other vessels where you are, what you’re doing, and—most important—whether you’re anchored, under way, or maneuvering to avoid a collision. Among these signals, one rule stands out for anchored vessels: a short blast every minute. Let’s unpack what that means and why it matters.

Anchored vessels and Rule 35: the one-minute heartbeat

In the COLREGs, Rule 35 is all about sound signals. It isn’t there to complicate things; it’s there to save them. For a vessel at anchor, the rule specifies that a short blast should be sounded at intervals of every one minute. Think of it as a steady heartbeat that says, “I’m here. I’m anchored. I’m not moving.” The exact duration of a “short blast” is simple and unmistakable—roughly a second or so. The point isn’t to blare forever, but to create a predictable rhythm that nearby boats can detect and understand, even if visibility isn’t ideal.

Why a one-minute interval? It’s a careful balance

If you’ve ever listened to a sequence of blasts from a vessel at anchor, you’ve felt the purpose behind the timing. Too frequent signals would irritate and degrade the signal quality—the nautical equivalent of someone loudly tapping a desk. Too sparse, and approaching vessels might miss you entirely, especially in fog, rain, or night when sight lines are limited. One minute is the sweet spot. It’s long enough that the sound doesn’t become background noise, short enough that other mariners aren’t left guessing whether you’re still anchored or have drifted off. In a nutshell: it’s enough to keep you visible to the radar of human attention and to any listening watch aboard nearby ships.

What this signal actually communicates

• “I’m anchored and not under way.” The signal confirms your status and helps others avoid misinterpreting your position as a vessel in motion.

• “I’ll be here for a while.” The cadence communicates predictability; you’re not likely to lurch forward suddenly, which helps others plan their own course adjustments.

• “I’m in the area, so please monitor your bearings.” The sound signal is a cue to maintain situational awareness in the surrounding traffic pattern.

Real-life moments where the signal matters

Imagine you’re anchored in a busy channel at dusk. The water’s choppy enough to jostle small boats, and the harbor is a hive of activity. A fishing vessel slips into the same narrow pass, its engine rumbling; a container ship looms in the distance, lights blinking like a city on the water. If a vessel is anchored, the one-minute blast becomes a reference point. Other mariners hear a cadence they expect and can adjust their bearings and speed to avoid crowding you out of the central channel. It’s a simple, practical rule that reduces confusion when visibility isn’t perfect and helps maintain safe distances between vessels.

What to do when you hear that signal

• Acknowledge and interpret the status. If you’re piloting a smaller craft or another commercial vessel nearby, treat the signal as a cue that there’s an anchored vessel in the area.

• Don’t assume you have right of way. The signal doesn’t grant status; it communicates it. You still need to navigate according to the other COLREGs rules—keep safe distance, monitor your speed, and be prepared to take early action if the wind or current shifts.

• Use your listening skills. In rough weather or in crowded waters, hearing the pattern clearly can be more important than sight. If you’re uncertain about a sound signal, slow down, take a wider berth, and reassess your options.

A moment to connect the dots with other signals

Sound signals are one part of a broader set of visibility tools. You’ll also want to consider:

• Fog signals and their longer, more deliberate blasts.

• Day shapes and lights that indicate a vessel’s status at a glance, when you’re within sight of each other.

• The distinction between a short blast (about a second) and a prolonged blast (often used to signal a different situation, like distress or danger, under other rules).

Putting the one-minute rule into a mental model

Let me explain it this way: imagine you’re at a party and you casually say hello every sixty seconds to let your friends know you’re still around. If you stop that rhythm, someone might assume you’ve left or that you’re ignoring them. The anchored vessel signal works the same—it's a reliable reminder to nearby mariners that you’re in a fixed spot, and it helps them gauge how to maneuver around you safely. The consistency of the signal is as important as the signal itself.

Common questions and quick clarifications

• Do you have to signal at night, in fog, or during daylight? Yes. The rule applies under all conditions; the purpose is to ensure visibility and awareness, not to create a mood for specialized times.

• Can a vessel at anchor skip the signal if the wind is calm? No. The signal cadence is a rule-based practice, designed to be consistent regardless of weather or tide.

• What if I’m in a crowded harbor and a loud engine drowns out the sound? If you can’t hear it, assume there’s a need for caution. Maintain a safe distance and monitor the surroundings. When you do hear it, respond as you would to any other important navigational cue.

Integrating this into mindful navigation

For anyone spending time on the water—whether you’re a commercial operator, a harbor pilot, or a recreational sailor—the anchored-vessel signal is more than a rule; it’s a shared code. It’s part of the water’s language that keeps traffic organized and accidents at bay. When you understand the cadence, you start to notice the subtle choreography that governs the sea: who yields, who passes, who holds position. It’s a discipline, yes, but it’s also a respect for the space other people are sharing with you.

A few practical tips you can carry forward

• Listen actively. If you hear a short blast at regular intervals, treat it as a cue to keep your distance and watch your own speed.

• Keep a mental checklist. If you’re the one maneuvering near an anchored vessel, slow down, avoid abrupt turns, and give the other boat ample room to maneuver if needed.

• Practice good watchkeeping. Even when the water looks calm, conditions can change quickly. Regular sound signals help your crew stay alert and ready to respond.

Final thoughts: a simple rule with real-world impact

There’s something wonderfully straightforward about the one-minute signal for anchored vessels. A short blast, repeated every sixty seconds, creates a dependable rhythm that anchors your safety—and the safety of others—in place. It’s a small, precise act, but it carries a lot of weight. In the grand stream of maritime navigation, these signals are anchor points we can all rely on, moments of clarity in the shifting tides.

If you’re curious about how this fits into the broader tapestry of COLREGs, you’ll notice similar patterns everywhere: set phrases, clear timings, and signals that reduce ambiguity. It’s not about memorizing every detail in a vacuum; it’s about understanding why those details exist and how they help real people on real boats stay safe. And that, in the end, is what good seamanship is all about.