Abeam

Abeam means bearing 090 degrees or 270 degrees relative to own ship’s heading, at right angles to the fore-and-aft line on either beam. It is a relative bearing referenced to the ship’s head, not to true or compass north, so a mark reported abeam to starboard lies 090 degrees relative. The point of beam passage is used in the four-point bow-and-beam method to read distance off, in parallel indexing as the closest-approach reference to a beam object, and in timing passing distances during pilotage. Adding the abeam relative bearing to true heading gives the object’s true bearing.