How to safely cross a Traffic Separation Scheme by waiting for a clear opening in oncoming traffic.

In a Traffic Separation Scheme (TSS), crossing traffic isn’t a game of hurry up. It’s a careful, measured move. The lanes are there to organize busy sea lanes, reduce crossing risks, and keep ships moving smoothly. When you’re approaching a cross-traffic situation inside a TSS, the safest play is to wait for an opening in the oncoming traffic before you cross. That pause might feel like a drag, but it’s the kind of patience that keeps everyone sailing safely.

Why waiting is the smart move

• Visibility matters. In a congested area, you can’t rely on luck. Waiting gives you the chance to see how approaching vessels are behaving—speed, course, and distance.

• You’re reading the room. A TSS is a managed highway on the water. Cars don’t suddenly appear in your blind spot the way they might on a city street; ships give predictable, but still dynamic, signals. The pause helps you align with that flow.

• You protect your crew and your vessel. A quick crossing with uncertain gaps invites misjudgment. Slowing down and waiting for a safe opening reduces the odds of close calls or near misses, and that’s worth more than a few extra minutes.

What counts as an opening

An opening isn’t a magical moment; it’s a safe window. You’re looking for:

• Sufficient distance: enough separation to cross without forcing a speed change on others or creating a squeeze.

• Manageable speed: the oncoming vessel should have a comfortable range and relative speed so you can estimate how long you’ll need to complete the crossing.

• Clear angles: you want to cross at a near-right angle to the traffic flow if possible, which minimizes the time you spend in the other lane and reduces the chance of crossing in the wake of a fast-moving vessel.

Think of it like crossing a busy street with pedestrians in a city center. You don’t step out until a clear gap appears, you check both sides, and you time your walk so nobody cuts in front of you. A TSS is a maritime version of that logic, just with bigger ships and longer horizons.

How to prepare for the crossing

Let me break it down into practical steps you can picture in your head as you approach:

• Scan and reassess: keep a sharp lookout for vessels in the opposite direction of your intended crossing. Use VHF, radar, AIS, and binoculars if you’ve got them. You’re building a mental map of who’s moving and how fast.

• Talk the situation through: if there’s a crew on watch, share the plan. A quick verbal check can prevent miscommunications. In busy waters, a brief acknowledgement of “crossing now” or “waiting for gap” helps everyone stay coordinated.

• Gauge distance and speed: estimate how many nautical miles you have before you’ll be in the other lane and how quickly you’ll cover that stretch. If you’re not confident about the numbers, wait a little longer.

• Adjust speed as needed: you don’t want to surprise others with a sudden movement. If you need a bit more time, ease your speed smoothly and maintain steady control.

Crossing with care

When you finally see a suitable opening, here’s how to execute with poise:

• Set a near-90-degree crossing angle: aim to slide across the lane quickly but safely, minimizing the time you stay in the other traffic stream.

• Keep a steady course and speed: abrupt changes can confuse other vessels. A clear, smooth motion is easier for everyone to read, especially in limited visibility or rough seas.

• Maintain a wide lookout and a generous safety margin: even if you think you’ve found a perfect gap, keep an extra watch out. The sea is full of small, sudden surprises—wind shifts, wake, a vessel’s speed change, or a stubborn current.

• Be ready to abort: if the gap narrows or a vessel adjusts speed, be prepared to stop crossing and wait again. It’s better to wait another minute than to push through a risky moment.

What about the alternatives?

• Using visual signals to communicate (A) helps, but signals alone aren’t a guaranteed protection. They’re part of the picture, not the whole solution.

• Adjusting speed to match surrounding vessels (B) can be useful in some contexts, but in a TSS the priority is safe crossing rather than chasing a perfect speed match. It’s easy to misjudge how another ship will respond.

• Overtaking whenever possible (D) is a dangerous and poor strategy in a TSS. You don’t want to force a crossing just because you feel you must stay in motion. It increases the risk of collisions and disrupts the orderly flow of traffic.

In the end, the best move is the patient one: wait for a safe opening in oncoming traffic before you cross. It aligns with the core COLREGs intention to avoid collisions and to navigate with caution. You’re not simply following a rule—you’re practicing smart seamanship that keeps your crew secure and the voyage on track.

Tips from the real world

• Use all tools at hand. Radar and AIS give you more time to judge gaps. Don’t rely on one signal alone.

• Keep a generous lookout. The human brain is great at pattern recognition, but on busy water, a second or third glance saves you from missing something early.

• Communicate clearly but concisely. A quick VHF message like “crossing TSS, open gap ahead” can help nearby vessels anticipate your movement.

• Practice in calm moments. When the sea is quiet, rehearse the crossing sequence in your mind. It helps you stay calm when traffic thickens.

A few thoughts on the broader picture

Many mariners describe TSSs as river-like corridors with defined lanes. The idea is simple in words but mighty in practice: stay in your lane, keep a safe distance, and only move when you’re sure you have a clear, safe window. The moment you act too soon or too late, the plan starts to fray. That’s when tensions rise and the risk goes up. Training helps you move from reaction to deliberate, careful action.

If you’ve ever watched ships drift through a narrow channel and wondered, how do they know when to go? This is the essence: crossing a TSS is less about speed and more about timing. It’s about seeing the big picture—where every vessel is headed, how fast they’re moving, and whether there’s room to slip across without forcing anyone else to slow down or alter course.

A final note

Crossing a TSS safely isn’t a one-size-fits-all move. Weather, visibility, vessel size, and crew readiness all shape what you can pull off in a given moment. The constant thread is patience and careful judgment. If you’ve got a moment of doubt, that’s the moment to wait. A shorter cross could pull you into the next stretch with fewer headaches—and a lot more peace of mind for your crew.

So, the next time you’re charting a course through a Traffic Separation Scheme, remember this: the smart play is to wait for a safe opening in oncoming traffic before you cross. It’s a straightforward rule with a big impact. It’s the kind of decision that separates confident mariners from the rest—not because they rush, but because they read the sea well and act when the moment is right.