Sea rules of the road and their role in avoiding ship collisions

Sea rules of the road and their role in avoiding ship collisions
Page content

Part B of the ROR/Navigation Rules of the Road

Part B of the Collision Regulations (or Colregs) is divided into three Sections. The first section deals with rules in all conditions of visibility, whether normal or restricted (by fog, rain or any other reason)

Rule 5 covers lookouts, a commonsense precaution that is often neglected- basically, this is ‘keeping an eye out for other ships and dangers’. The lookout(s) must be able to hear as well as see other ships and dangers. (‘hear’ includes listening to their foghorn, by which ships alert each other of their intentions at sea, using basic morse code in a manner also prescribed by the Colregs.) Note that a lookout is required at all times, even at anchor.

Just like your cars on the road, a critical rule requires a ship to maintain safe speed at all times. This can vary depending on circumstances, eg busy shipping lanes, poor visibility, other hazards etc.

Some sea rules of the road cover the proper use and interpretation of radar and the determining of a risk of collision (will the ship I am seeing collide with me or pass dangerously close?).

Other logical rules include the requirement that if some action is required of you, such as a change of course or speed, it should be made soon to be effective, and large enough to be obvious to the other vessel. A change of course is usually more obvious than a change of speed, but the give way vessel must slow down if required for safety.

Another rule requires a ship to stay on the right (starboard) side of a narrow waterway- the equivalent of driving on the right side of a road on land.

How do you know if there is risk of collision?

(click on pic for clarity)

There are many ways to determine this, including automatic ones like the Radar (ARPA or Automated Radar Plotting Aids) which tell you how close a ship will pass to you- or, indeed, collide with you- provided none of you makes any changes to course and speed and after how long, besides other information.

The easiest way is to take compass bearings of the other vessel. If there is no appreciable change over time (say, six minutes), then a risk of collision exists and action must be taken by the give way vessel.

Rule 10. Traffic Seperation Schemes (TSS)

A very important rule that covers areas of the oceans that have been internationally agreed to have a TSS covering them. A TSS is, essentially, a ‘road map’ marked on a navigators chart, which shows roads (or lanes), the lane a ship must take when going in a given direction and how she must behave within the TSS. The TSS coverage areas are usually areas of high traffic density; hence this attempt to ‘regulate’ the traffic. Ships are not bound to use the TSS all the time, but whenever they do- or are in the vicinity of a TSS, they must follow Rule 10.

Some salient features of this rule:

  • All vessels crossing the TSS (coming from an area outside it and going to an area outside it) must cross the TSS at right angles to the traffic lane, presenting a full profile to ships within the lane. (Similar to a crossroads like situation).

  • No vessel should “impede the safe passage of a power driven vessel following a traffic lane.” The aim should be to cross as quickly as possible.

Note that the rules discussed here apply in any condition of visibility. The next article will discuss rules which apply only when vessels can see each other.

This post is part of the series: Marine Navigation: The Rules of the Road

The first article will explain basic concepts and definitions. Subsequent ones will go in some detail in the nitty gritty and explanation of the Rules.

  1. The Basics of the Sea Rules of the Road in Navigation
  2. Basics of the Sea: Rules of the Road - In any Condition of Visibility.
  3. Basics of the Navigation Rules: When ships can see each other, and when they can’t
  4. Basics of Sea Collision Regulations: Lights, Shapes, and Sound Signals