Understand when the stand-on vessel must sound signals under COLREGs Rules of the Road

Understanding the moment to sound your horn can feel like a tiny nerve-wracking puzzle out on the water. You’re not just steering a vessel; you’re coordinating with the other guy who’s also trying to stay in one piece. In COLREGs, some rules are crystal clear, and others rely on good judgment plus clear communication. Today, we’ll focus on a specific, practical question: when must the stand-on vessel use sound signals? The short answer is simple, but the why behind it is surprisingly important.

A quick refresher: stand-on vs give-way

Before we dive into signaling, let’s frame the situation. In many crossing scenarios, one vessel is designated the stand-on vessel and the other the give-way vessel. The stand-on vessel technically has the right of way and should keep her course and speed, at least initially. The give-way vessel should take early and substantial action to avoid a collision. The whole point of COLREGs is to keep two boats from becoming one tangled mess.

What the question is really asking

The scenario you’ll often see in tests and in real life is this: the stand-on vessel is considering changing course, but the give-way vessel isn’t making any visible changes to her own course or speed. In that moment, the stand-on vessel is obligated to signal her intended maneuver. In plain terms: if you’re the stand-on vessel and you decide you must alter your course because the other boat isn’t shifting course, you should communicate that intention with sound signals.

So, the correct choice among the common options is: B — when she alters her course if the give-way vessel is not altering hers. The other options—passing at night, approaching a port, or navigating in a narrow channel—don’t specify the maneuver-triggered signaling that the question is highlighting. They describe different operational contexts where signaling may or may not be used, but they don’t pinpoint the moment when signaling is required to resolve a potential conflict of actions.

Why signaling in this moment matters

Here’s the thing: you’re not guessing. You’re trying to prevent a collision in a situation where actions aren’t immediately obvious to the other vessel. Sound signals are a universal language on the water. They help to bridge the gap when visibility is limited, when lights aren’t enough, or when both boats are close and the situation could become ambiguous in a heartbeat. Even if you’re technically in the right of way, signaling can prevent misunderstandings and give the other skipper a mental and audible cue to adjust.

Think of it like a city street where someone tries to merge into your lane. You’re keeping your pace, but you flash a quick signal to let them know you’re aware of their approach and you’re taking this side of the street. It’s courtesy, yes, but more importantly, it’s safety in motion.

A closer look at the signaling moment

If you’re the stand-on vessel and you realize the give-way vessel isn’t altering her path in time, you’ll alter your own course to avoid a collision. At that moment, you should use sound signals to announce your intention. This is not about shouting at the other captain; it’s about providing a clear, audible cue that you are changing course. The goal is obvious: reduce the ambiguity between two moving vessels and steer toward safe separation.

What about the other possibilities (just to clarify)

• A. When passing another vessel at night — Night maneuvers come with their own set of precautions. You’ll still need to monitor signals and lights, but the specific rule requiring a stand-on vessel to signal when she changes course because the give-way vessel isn’t changing hers doesn’t hinge on “passing at night.” It hinges on the action of altering course in the cross-threat scenario.

• C. When approaching a port — Port approaches involve a host of navigational rules, traffic separation schemes, and sometimes pilot boarding. Signaling is essential in many contexts, but the precise requirement described here is about signaling when you alter course while the give-way vessel isn’t matching that action.

• D. When navigating in a narrow channel — Narrow channels demand heightened awareness and sometimes special signaling, especially if you’re restricted by depth or traffic. Yet, the rule in question centers on the stand-on vessel altering course in response to a non-altering give-way vessel, not on every situation in a narrow channel.

Bringing it together with practical guidance

Here are a few practical takeaways you can tuck into your mental toolbox next time you’re on the water:

• Always keep a vigilant lookout. The decision to signal comes from recognizing that the other vessel’s actions aren’t aligning with yours quickly enough to avoid danger.

• Use sound signals to communicate intent when you must alter course because the other vessel isn’t changing hers. This isn’t optional; it’s about reducing ambiguity and increasing predictability.

• Remember that signaling is about intent, not punishment. The horn doesn’t win or lose a battle; it clarifies what you’re about to do.

• In poor visibility, rely on rules of the road plus signals to maintain a safe plan of action. Lights and shapes matter, but sound signals can cut through confusion when visibility is compromised.

• After signaling, monitor the other vessel’s response. If she still doesn’t alter course, you may need to complete the maneuver and ensure your course change provides safe separation.

How to think about these rules in real life

A helpful analogy is driving with a courteous but assertive driver in heavy traffic. If you’re in the stand-on position and you see a potential clash, you don’t just hold your line and hope the other driver notices you. You communicate your intended move—via signals in the marine world—so the other driver (or skipper) can adjust. If they don’t, you proceed with caution, keeping safety as the north star.

The role of signals in the broader COLREGs framework

COLREGs aren’t just a dry rulebook; they’re a safety framework built on communication. Rule-based navigation isn’t about micromanaging every move; it’s about predictable behavior so nearby vessels can anticipate what you’ll do next. In this light, signaling when you alter your course because the other vessel isn’t altering hers is one of the simplest, clearest ways to keep the water safer for everyone.

Practical tips for captains and crew

• Make signaling part of your standard operating procedure. When you’re thinking about changing course due to another vessel’s behavior, plan to use a sound signal to indicate your intent.

• Practice the timing. You don’t want to signal too early or too late. The goal is to give the other vessel enough lead time to react without causing confusion.

• Pair signals with other cues. Use lights, AIS, and VHF communications as additional confirmation of your intent. A coordinated approach reduces the chance of misinterpretation.

• Teach this rule at the deckplate level. If you’re in a crew setting, make sure the lookouts and helmsmen understand when signaling is required and why it matters.

A few notes on sources and continuing study

For those who want to ground this in the official framework, the International Regulations for Preventing Collisions at Sea (COLREGs) provide the details. You’ll see the logic laid out in the sections that discuss stand-on and give-way vessels, as well as the chapter dedicated to sound signals. In practice, many mariners also refer to regional addenda and guidance from organizations like the U.S. Coast Guard or the maritime authority in their country. It’s always worth checking the latest official text and any local adaptations that apply to your waters.

Bringing it home

So, to recap in a sentence: the stand-on vessel must use sound signals when she alters her course if the give-way vessel is not altering hers. It’s a rule designed to keep a few critical seconds clear, to prevent collisions, and to maintain a shared sense of what’s happening on the water. It sounds simple, but its impact on safety is real. A quick horn, a clear intent, and suddenly two crews can navigate through potential trouble with less risk.

If you’re curious to learn more, consider reviewing the sections on sound signals and maneuvering in COLREGs, and keep the practical mindset handy: vigilance, communication, and a calm, deliberate approach to any close-quarters scenario. The ocean rewards clarity, and a well-timed signal is a small act that makes a big difference.

Key takeaways

• The stand-on vessel signals when she alters her course if the give-way vessel isn’t altering hers.

• Signals are a practical way to communicate intent and prevent misinterpretation in close-quarters or low-visibility conditions.

• Other scenarios (night passing, port approaches, narrow channels) involve broader navigational considerations, but the rule highlighted here hinges on the interaction where one vessel changes course and the other does not.

• Stay safe by combining sound signals with lights, AIS, and good lookout practices, and consult official COLREGs for full details.

If you want a clear, accessible refresher on these concepts, you’ll find it in the official navigational rules and the practical guidance many mariners use day to day. It’s all about clear communication on the water—one horn blast at a time.