Why Supertankers Need 20 Minutes Just to Stop

Imagine you're piloting a vessel the length of four football fields, carrying enough crude oil to fill 2,000 Olympic swimming pools. Now imagine someone tells you to stop. You'll be traveling for another 20 minutes before your ship finally comes to rest—covering anywhere from 3 to 5 miles in the process.

This is the reality of commanding a supertanker, and it's a perfect illustration of Newton's first law of motion playing out on a mind-boggling scale.

The Physics of Stopping a Floating Skyscraper

Supertankers—technically called Very Large Crude Carriers (VLCCs) or Ultra Large Crude Carriers (ULCCs)—can weigh up to 500,000 tons when fully loaded. That's roughly the weight of 3,000 blue whales or 100,000 elephants, all moving forward at 15-16 knots (about 17-18 mph).

The issue isn't speed—it's momentum, which is mass times velocity. When you have that much mass, even moderate speeds create enormous momentum. And according to physics, an object in motion wants to stay in motion unless acted upon by an external force.

The problem? There's not much force available to stop a supertanker. Unlike a car with powerful brakes creating friction against the road, ships have only their propellers and rudders working against water resistance.

How Captains Actually Stop These Giants

When a supertanker captain needs to stop, they can't just slam on the brakes. The standard procedure is to reverse the ship's engines to full astern—essentially running the propellers backward to push against the ship's forward motion. Even then, the ship's tremendous inertia keeps it gliding forward.

In an emergency "crash stop" maneuver, where engines are immediately thrown into full reverse, the absolute minimum stopping time is about 14 minutes. But under normal operating conditions, 20 minutes is standard.

This is why most supertanker captains begin their stopping procedure about 15 miles from port. They need every bit of that distance to slow down safely.

The Turning Problem Is Even Worse

If you think stopping is hard, try turning. A fully loaded supertanker has a turning circle with a diameter of more than three ship lengths. For a 330-meter VLCC, that means a turning circle nearly a kilometer wide—about 10 football fields across.

This is why collision avoidance at sea requires planning hours in advance. By the time you see another vessel and decide to turn, you've already committed to whatever path you're on. These ships don't dodge—they plan.

Why This Matters

Understanding supertanker physics isn't just trivia—it's crucial for maritime safety. These vessels transport about 60% of the world's oil, and a collision or grounding can result in catastrophic environmental damage.

The Exxon Valdez disaster happened partly because the ship couldn't maneuver quickly enough to avoid a reef. Modern shipping lanes, traffic separation schemes, and vessel traffic services all exist because these giants need extraordinary amounts of time and space to operate safely.

Next time you're stuck in traffic and frustrated that the car ahead won't move faster, remember: at least your vehicle doesn't need 20 minutes and 5 miles just to stop.