Ocean Cpa Method.pdf May 2026

Uses radio waves to track the relative bearing and range of nearby targets.

The is the estimated position where the distance between two ships (the "own ship" and a "target vessel") reaches its absolute minimum. It is the primary metric used by Watchkeeping Officers to assess the Risk of Collision (ROC) . If the CPA is too small, a collision is possible, requiring immediate maneuvering according to COLREGs . 2. Core Parameters The method relies on two primary mathematical outputs: Ocean CPA method.pdf

Calculated by dividing the relative distance projection by the relative speed. Uses radio waves to track the relative bearing

Provides GPS-based data including SOG (Speed Over Ground) and COG (Course Over Ground). 4. Calculation Methodology If the CPA is too small, a collision

The direction of the target's movement relative to the own ship.

Defining a "safe zone" around a ship rather than a single point.

The CPA is traditionally calculated using vector geometry. Determine Relative Velocity ( Vrcap V sub r