Determining the Risk of Collision

COLREGS Actions Critical to Stand-On or Give-Way Boats

Aug 30, 2007 Alan Sorum

Knowing how to avoid a collision is a basic boating skill that is easy to learn. This skill begins with an understanding of the danger zone on a boat.

The International Regulations for Avoiding Collisions at Sea (COLREGS) are the rules of the road for boaters. COLREGS breaks boats into two categories of when they meet, either to be stand-on or give-way. A stand-on vessel is expected to maintain its course and speed, not making any unexpected maneuvers. The give-way boat is responsible for taking whatever measures are necessary to avoid collision with the stand-on vessel.

Determining Vessel Status - COLREGS rules identify and define several zones around a boat to determine its operational responsibilities. The rules delineate port, starboard and stern zones. Using the bow as the zero point, the starboard section runs from 0° to 112.5° or in nautical parlance 22.5° abaft or behind the starboard beam. The stern sector runs a total of 135° from 112.5° to 247.5°. The port sector is found between 247.5° to 360° or 0°. Each of these sectors is color coded and reflects the color of installed navigation lights. The starboard sector is green, the stern portion white and port sector red. Under the rules of the road, the starboard or green sector is known as the danger zone.

The Danger Zone - The danger zone is identified in the daytime by viewing an approaching boat and at night by the green navigation light. When two vessels approach each other, the one that can see or observe the green sector is the stand-on boat and the one who sees the red must give-way. Seeing green means go or continue, and red means there is danger in persisting with the approach. As a stand-on boat you are required to maintain course and speed, but remain ready to take action if the give-way vessel does not respond correctly.

Determining Risk of Collision at Night - Avoiding a collision depends on properly identifying which vessel is to stand-on. A collision can occur through three basic scenarios:

• If you see both the red and green navigation lights of an approaching boat, you are meeting head-on. COLREGS requires both boats to give-way in this situation to alter their course to starboard or the right.
• If you see a single white light ahead, there is a good chance you are overtaking another vessel. You as the overtaking boat must give-way and maneuver to avoid the boat ahead.
• If you see the red navigation light of another vessel, you are the give-way boat in a crossing situation and must maneuver to your starboard side or slow down to pass behind the stand-on boat.

Knowing how to avoid a collision is a basic boating skill that is easy to learn. Boaters depend on each other to understand the COLREGS and operate in a predictable manner.

The copyright of the article Determining the Risk of Collision in Boating & Sailing is owned by Alan Sorum. Permission to republish Determining the Risk of Collision in print or online must be granted by the author in writing.

Boat Zones