The image also requires interpretation, and ‘radar assisted collisions’ have long been an issue. In doing so, it’s possible to lose sight of vessels with small radar signatures, such as yachts made of fibreglass. The picture depends on the set being tuned properly to be as sensitive as possible, while editing out wave clutter and rain. It doesn’t give you numerical data though. ![]() Much like the changing noise of a siren as it passes by, Doppler processing quickly detects if a target is moving towards you or going away and can then mark the target accordingly to identify risk of collision. MARPA (Mini Automatic Radar Plotting Aid) allows you to manually select radar targets which are then automatically tracked, giving you information such as closest point of approach (CPA) and time to CPA (TCPA). The latest radars will also let you view your radar plot at two different scales simultaneously. If your radar is connected to your NMEA network and chartplotter it will be able to overlay the radar picture onto the electronic chart, helping you decipher the picture, as well as your AIS screen, so you can match up radar targets with AIS contacts. Without getting mired in proprietary names, the following are some of the key innovations. The software that goes with them is also developing quickly, adding new functions and making it easier to interpret the key information from the radar display. Manufacturers are constantly working to make their radars have lower power consumption, better image resolution and greater range. More recently, radar technology has moved away from analogue magnetron systems to digital radar, which operates at a much lower power. It also has the benefit of revealing objects that are not charted or actively transmitting, including unmarked vessels, weather, and squalls. While GPS chartplotters have largely replaced this function, data provided by radar is not subject to datum shifts and gives a highly accurate picture of where your vessel is in relation to land. ![]() Making yourself as visible as possible on both systems is common sense It also worked well as a means of blind pilotage, allowing a course to be steered relative to land otherwise unseen.Ĭommercial shipping relies heavily on radar and AIS for collision avoidance. Put simply, it sends out a signal and listens for an echo in order to plot the range and bearing of anything solid, like land or other vessels.īy tracking the changes of range and bearing relative to your vessel, and applying Rule 19 when navigating in fog, it is a hugely useful tool for collision avoidance, but historically it needed some skill to operate effectively. Radar (Radio Detection And Ranging), which really came of age in the Second World War, is perhaps the most established of the three. ![]() With decisions to make for fitting out my own boat, Aurial, a Southerly 105 ketch, I set about exploring my navigation options. While radar was once the only real option for blind navigation and collision avoidance, there is now a range of technology to help yachts wanting to see and be seen, but each of the options has its own strengths and limitations. AIS, radar target enhancers and radar each give an added layer of observation to the ‘Mk1 eyeball’. This is where electronic aids can be of use. We would all welcome any extra help in spotting other vessels and to make sure we are seen. ![]() You can track a target with MARPA to see if it presents a collision risk
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