What is the rule 13 in Colregs

Okay, so Rule 13 in the COLREGs – that's the International Regulations for Preventing Collisions at Sea – it's all about overtaking. It tells you exactly when you're overtaking someone and what you're supposed to do about it. The big idea? If you're the one doing the overtaking, you have to stay out of the other boat's way. Completely. Until you're well past them and there's zero chance of hitting them.

Here's the deal: you're officially "overtaking" if you're coming up on another vessel from more than 22.5 degrees behind its beam. Basically, if you can only see its stern light and none of its sidelights, you're overtaking. This doesn't matter if it's sunny, foggy, night, or you're in a narrow channel or a traffic separation scheme – the rule sticks.

So, you're the "give-way" vessel. You need to take big, early action to keep clear. The other boat, the one being overtaken, is the "stand-on" vessel. They're supposed to just keep doing what they're doing – same course, same speed. But, if it looks like you're not doing enough to avoid a crash, they have to act too. And here's the kicker: Rule 13 trumps the head-on and crossing rules (that's Rules 14 and 15) whenever you're overtaking.

When does Rule 13 apply?

It applies whenever one boat is overtaking another. Doesn't matter if it's day, night, fog, or clear skies. The whole thing hinges on your position and the angle you're coming from. You're overtaking if you're coming from more than 22.5 degrees behind the other boat's beam. That means you're in a 135-degree arc on either side of their stern.

And it applies from the second you spot them behind you until you're "finally past and clear." That just means you've passed them completely and there's no more risk of bumping into each other. Even if you end up alongside or ahead of them later, you're still the give-way vessel as long as the overtaking situation is happening.

What are the duties of the overtaking vessel?

Pretty simple: stay out of the way. That means taking early, substantial action. You could turn to starboard to pass on their port side, slow down, or even stop. Don't cut in front of them unless it's totally safe.

Also, if visibility is bad and you can see each other, you gotta sound the right signals. In open water with clear visibility, no signal needed for overtaking. But in restricted visibility, you'd sound one long blast followed by two short ones to say you're overtaking on their starboard side, or one long and two short for the port side. Wait, that's the same signal – I mean, you just use that signal to announce your intention.

What are the duties of the vessel being overtaken?

You're the stand-on vessel. Just hold your course and speed. Don't do anything that might mess with the overtaking boat, like turning towards them. But if they're not doing enough, you've got to take action to avoid a collision. That's a last resort. Blow five short, rapid blasts on your horn to show you're not sure what they're doing. Then, you might turn to starboard or slow down.

How does Rule 13 differ from Rule 14 and 15?

Rule 13 takes priority. So if you're overtaking someone, the overtaking rules apply even if you later end up in a crossing or head-on situation. You're still the give-way vessel until you're finally past and clear.

What is the 22.5-degree angle rule?

This is the core of Rule 13. It defines the overtaking zone. You're overtaking if you're approaching from more than 22.5 degrees behind their beam. That's a 135-degree arc on either side of their stern. Practically, if you can't see both of their sidelights and only see their stern light, you're overtaking.

The angle is measured from the stern of the boat being overtaken. If you're within 22.5 degrees of their stern, you're overtaking. If you're further out, it's a crossing situation. This angle is what decides which rule kicks in.

What are common mistakes with Rule 13?

• Assuming overtaking ends too early: People think it's over when they're alongside. Nope. You're still the give-way vessel until you're finally past and clear.
• Failing to sound signals: In bad visibility, you have to sound signals. Skip it, and you're asking for trouble.
• Stand-on vessel taking premature action: The stand-on boat should just hold steady unless a crash is about to happen. Doing something too early just confuses everyone.
• Not accounting for speed: Overtaking isn't just about position; it's about speed difference. A faster boat overtaking a slower one has to act even if it's not technically in the overtaking sector yet.

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