ARPA: Automatic Radar Plotting Aid

Developed for marine usage in the 1970’s. Fittings aboard tankers were made mandatory in 1982, or other classes of ships soon after. On an ARPA the radar observer can designate a “target” ship of interest and the ARPA calculates the speed and course of the ship and assesses the risk of collision. Targets may also be “acquired” automatically and tracked. A number of targets can be tracked simultaneously. A “dangerous” target (one having a risk of collision) will be highlighted and an alarm will sound. On any target being tracked, the closest point of approach (CPA) and time to closest point of approach (TCPA) are calculated and displayed. Development of ARPA started after the accident when the Italian liner SS Andrea Doria collided in dense fog and sank off the east coast of the United States. ARPA radars started to emerge in the 1960s and, with the development of microelectronics. The first commercially available ARPA was delivered to the cargo liner MV Taimyr in 1969 and was manufactured by Norcontrol, now a part of Kongsberg Maritime. ARPA-enabled radars are now available even for small yachts.

Raytheon Marine Co. – RAYCAS V 1660/12SS

Manufactured by: Raytheon Marine Co.

Model: RAYCAS V 1660/12SS

Date of Mfg: 5/82 (Display), 2/82 (Transceiver)

Power Requirements: 115VAC

Operating Frequency: 3070 +-50 MHz, Output power 60KW

Pulse Repetition Frequencies: 3600, 1800, 900 Hz