RADAR | Mariners Toy

In a 200 over meters in length of a ship is been controlled just by the tip of fingers by deck officers. Isn't it a coolest thing? Obviously yes, because it's a fact that we the merchant navy officers have been trained for it. During my diploma programme, I've been given the chance of getting into the simulators and sail the ship in and out of congested waters with high traffic density.

The main equipment for the ship's safe navigation is the Marine Radio Direction and Ranging (RADAR). Decades ago, there's no Automatic Radar Plotting Aid (ARPA) system for Radar to get the relevant information for safe passing distance and create tracks using the contacts. After World War II, the Britons has came up with this system which has the capability to calculate the tracked target's course, speed, closest point of approach (CPA), thereby showing the danger of collision with the other ships or lands.

ARPA RADAR Presentation

ARPA is more developed after the disaster of the Italian liner SS Andrea Doria collided with MS Stockholm in a restricted visibility and sank at the East Coast of United States. ARPA in marine radars established to emerge in the 1960's together with the development of microelectronics. A typical ARPA function gives a display of the current situation and uses computer technology to predict the situation according to the actions taken. ARPA actually assesses the risk of collision and enables the operator to see proposed maneuvres by own ship.

The following functions are normally provided by ARPA:

• Automatic and manual acquisition of targets
• Read-out of targets which provides courses, speed, range, bearing, closest point of approach (CPA) and time to closest point of approach (TCPA)
• True or relative motion presentation
• The ability to show collision assessment information directly on the Plan Position Indicator (PPI) using true or relative vectors
• The ability of trial maneuvers, including course changes, speed changes, and mixed course/speed changes
• Automatic ground stabilization for navigation purposes. 

Limitation
ARPA data is only as accurate as the data comes from inputs such as the gyro and speed log.