Which vessel is restricted in their ability to maneuver under COLREGs, and why do draft limits matter for safe navigation?

Navigating by the COLREGs means reading signs in the water that other mariners might miss. One of the trickier concepts is “restricted in her ability to maneuver.” This phrase isn’t about a mood or a mood swing—it’s a status that tells nearby vessels to keep extra space because the ship can’t move or turn as easily as others.

Here’s a straightforward way to think about it: when a vessel is truly limited in its ability to change course or speed, you treat it with heightened caution. That status isn’t assigned to every slow-going boat; it’s reserved for ships whose size, design, or operations restrict their maneuverability in a way that affects safety.

What does the question really ask?

Suppose you’re crossing a busy waterway and you’re weighing which vessel would be considered restricted in their ability to maneuver. The options look simple, but they flag different real-world situations:

• A. A vessel operating in a wide navigable channel

• B. A vessel engaged in fishing

• C. A vessel constrained by her draft

• D. A vessel at anchor

Let me explain why the correct choice is C, a vessel constrained by her draft.

Why this one is the key example

A vessel constrained by her draft is the classic example of being restricted in maneuverability. “Draft” means the depth of water a vessel needs to float safely, plus the space under her hull that must remain clear of the bottom. When water is shallow compared to the ship’s draft, the vessel can’t swing, back up, or pivot as easily as a lighter, shallower-draft vessel. A deep keel or a heavy load can turn even a big ship into a creature of inertia in shallow water. In COLREGs terms, that constraint is enough to classify the vessel as restricted in her ability to maneuver.

Think of it like driving a long truck through a narrow alley. The truck can go forward, but turning around or making sudden lane changes is tough or impossible without risking a scrape or a stall. In the same way, a vessel with a large draft, working in shallow water or an overloaded condition, carries the same “not easily moved” limitation. The mariner on deck knows this and communicates it—by expectation and by behavior—through the way they steer, speed, and position themselves relative to other vessels.

A quick look at the other options

• A vessel operating in a wide navigable channel: Not restricted in maneuverability. There’s ample room to maneuver, to turn, to adjust courses, and to respond to other traffic. In a broad channel, even big ships can change direction reasonably well—so this status doesn’t apply.

• A vessel engaged in fishing: There are fisheries-related hazards and gear that can complicate maneuvering, but a fishing vessel isn’t automatically classified as restricted in their ability to maneuver. It depends on how the gear is deployed and what the vessel can safely do at the moment. The key word is “automatically”—not every fishing operation places a vessel in the restricted category, even if it creates a hazard.

• A vessel at anchor: It’s not maneuvering, but that’s not the same as being restricted in ability to maneuver. An anchored vessel isn’t expected to respond with the same level of maneuverability as a moving vessel, and COLREGs treat it differently. The anchor status signals other considerations, but it doesn’t carry the same designation as “restricted in her ability to maneuver” for safety actions in crossing situations.

Why the distinction matters at sea

Rule 3 of the COLREGs lays out general definitions, and the phrase “restricted in her ability to maneuver” is a flag that tells other mariners to give extra space and to plan ahead. It’s not just a label; it’s a behavioral cue. When you’re piloting a vessel or sitting at the bridge watching traffic, recognizing this status helps prevent close-quarter situations that can escalate quickly in busy waters.

In practice, a crew member assumes you’ll see and respect a vessel that is restricted by draft or other constraints. You slow down a bit sooner, you plot a broader arc, and you avoid any last-second changes that could put you and the other vessel in danger. It’s a cooperative, safety-forward mindset that keeps waterway conveyances moving smoothly—even when space is tight.

A few practical takeaways for mariners

• Anticipate constraints in busy waterways: If you know you’re passing through shallow channels near shoals or a harbor approach, scan for vessels that might be drafting heavily or loaded near their limits. They could be less able to respond quickly to a crossing situation.

• Watch for obvious signals: A vessel with a deep draft in a shallow port, or one that’s listing or staying at a cautious speed, may be exercising restricted maneuverability. Give them space and plan your passage with a wider margin.

• Remember the other rules still apply: Even if a vessel isn’t restricted, every vessel must take action to avoid a collision if there’s a risk of one. The presence of a restricted-vessel usually means you should be even more prepared to alter course or reduce speed earlier.

• Use good lookout and communication: Keep a steady watch, use AIS information when available, and maintain clear communications with your crew and, if applicable, with nearby vessels or harbor authorities. The goal is predictability and predictability reduces risk.

A small digression that still fits

This topic bleeds into real-world operations you’ll encounter in harbors and on canals. Tugboats, dredging operations, and vessels laying underwater cables all have activities that can temporarily limit maneuverability. In those cases, the COLREGs and local traffic regimes often rely on specific signals, pilot arrangements, and defined traffic separation schemes to keep everyone moving safely. It’s a reminder that the water is a living system—rules work best when people read the signs and respond with proportionate care.

A quick note on how this lines up with other concepts

You’ll hear about not under command, restricted visibility, and other special statuses in the rules. Each status has its own implications for right of way and safe passage. “Restricted in her ability to maneuver” is often taught as one of the most intuitive to recognize because depth and draft are tangible, physical constraints you can assess at a glance in many situations. It helps you build the habit of thinking several moves ahead, much like chess on the waves.

Bringing it together

So, when you’re navigating a busy waterway and you come across a vessel that’s constrained by its draft, that’s the classic scenario where the other vessel should treat the situation with extra caution. It’s not about fear or hesitation; it’s about responsible seamanship—giving room, adjusting speed earlier, and maintaining a clear path of safe travel for everyone involved.

If this kind of scenario pops up in your daily reading of COLREGs, you’re not alone in the confusion. The core idea is simple: when a vessel’s ability to maneuver is truly restricted by physical realities like depth, you expect them to be less able to dodge, weave, or sprint out of trouble. Your response should be calm, measured, and anticipatory.

Final takeaway

A vessel constrained by her draft is the definitive example of being restricted in the ability to maneuver. This distinction helps keep crossing traffic predictable and safe, and it’s a good rule of thumb to apply whenever you’re assessing on-water scenarios. Keep an eye on water depth, hull design, and load, and you’ll be in a much better position to navigate safely beside big ships, narrow channels, and every other kind of traffic you’ll meet on the water.

If you’re curious to explore more about how these rules play out in real-life situations—like when dredging work or harbor pilots are in play—there are plenty of resources and real-world case studies that illustrate how the lid fits over the safe passage puzzle. The sea rewards awareness, careful planning, and a steady hand. And that steady hand, paired with a solid understanding of “restricted in her ability to maneuver,” goes a long way toward keeping everyone on board safe and sound.