Rate and Ratio in Radar Collision Avoidance

Abstract

Most authorities are agreed that detailed plotting is an essential part of a ship's radar collision-avoidance system, and teaching on the subject includes the calm intellectual detachment of the radar simulator; with First and Second Officers respectively to plot the data and evaluate the developing situation, decide upon the appropriate action and initiate the conn. In conflict with this ideal executive bridge manning concept is the increasing tendency towards automation and resultant crew reduction, to the point where in an increasing number of vessels (in particular the ever increasing number of specialized supply vessels in the offshore oil industry) spare capacity no longer exists to permit the separation of bridge functions such as lookout (Rule 29), radar observer, radar plotter and anti-collision conning. The dictates of low manning, long hours and arduous and often dangerous work on low freeboard, heaving sea-swept decks, all combine in such vessels to restrict bridge manning to a single navigating officer—as a rule on a six-hour shift—overseeing the gyro-steering, reading out and plotting from the position fixing system, operating the radios, keeping a weather eye on the various bridge-mounted engine gauges, observing the radar and, when necessary, overriding the gyro steering to manœuvre the ship manually in any collision-potential situation. Radar plotting is seldom undertaken in this class of vessel, there being a limit even to the accomplishments of the one-man-band.