Radar in Hi-Def and Digital | Sailing Blog - Technical Hints and Tips - Sailing Television

Radar in Hi-Def and Digital

Leaving Portsmouth Harbour onboard Raymarine’s test boat.
Yesterday we got a chance to go out on Raymarine’s amazing test and product development boat in Portsmouth Harbour on the Solent. The “Raymariner” is a 42 foot Hardy made here in the UK and it must have more electronics aboard than any other boat less than a hundred feet. I counted six radar arrays, 8 wind indicators and 14 GPS receivers on deck.
The boat has 7 (seven!!) complete autopilot systems! Yesterday was one of the first sunny spring days here. We were out for about 3 hours and got a chance to see the new HD radar technology in action. The area that would normally be the saloon on this boat has been purpose-built as a testing lab with desks that can patch into any of the sensors or systems. Using one of the new E-Wide series of Raymarine plotters (hybrid touch screens) we were able to compare various radar scanners operating in a real envirionment at sea. First we saw a large “open array” scanner, of course with excellent definition. I don’t have enough experience with the larger radars to compare but the images of the surrounding marks and coastline were very good. Stunning really!

But now they have HD Digital Radar. What does this really mean?

Lets take Digital Radar first. Traditional radar scanners have had very little of the working circuitry up in the radar itself. A huge thick cable runs from the display set up to the radome. But with digital radar, most of the functionality is moved up to the scanner. This has a number of advantages. The cable is much smaller saving quite a lot of weight aloft. It can talk to any display you have. We have 2 screens in the cockpit and previously that would mean the radar would have been run from one of them. So you would always need that on switched on to have radar. Now either display can run the radar. And I understand that digital radar makes a better image since the signal is interpreted right up in the scanner as it is received rather than travelling down the long wires to the display. Less signal loss.

HD - High Definition Radar - This sounds like just a buzz-word - can radar be “hi-def”? Well radar is really about definition. Defining a target by bouncing a signal pulse off it. Varying the pulse length and power allow you to get better definition, and measuring how strongly the signal comes back as well as how long it took to return (which means how far away it is)
With HD Radar the power of the modern computer is put to use tweaking the outgoing signal, and analyzing the returned pulse. Interpreting and analyzing means the radar can display an image that allows us to recognize the features we are interested in. The unit will tune itself and reduce sea clutter - even adapting to the different conditions. Below the menu shows easy setup to match conditions - “Buoy Mode, Harbour Mode, Offshore Mode and even “Bird Mode” to detect flocks of birds that might indicate good fishing!
We have had 2 previous Raymarine radars, both 18 inch radomes. I was interested to see how the smaller radome would benefit from the HD Digital technology. I asked to see an image with the smaller radome as that is what most sailboats use - fitting either an 18 or 24 inch scanner in a dome to avoid tangling rigging in a spinning open array scanner. The image looked very detailed and clear to me! One of the big improvements seemed to be the reduced amount of clutter and less tuning needed. The automatic modes combined with overlaying the image on the chart makes an image that is easily recognizable to someone who isn’t a radar expert. As most of us sail short-handed (without a dedicated navigator on board) then having an easy to use radar is a great asset.

Radar is still one of the best upgrades you can do to increase safety and reduce stress especially at night and in reduced visibility. Here are my radar hints...

  • Display should be mounted so it is visible from the helm so the skipper can make quick decisions
  • Practice with it on nice days when you can see what you are doing and compare real world to the radar display
  • Make sure the unit can be dimmed down enough to be used at night without ruining your night vision. Raymarine does this nicely and also has a night palette changing to darker colours.Try out the overlay mode where the radar image is synchorized and drawn on top of the chart (as above left) This is my favourite mode.
  • Get the first mate involved as well. Anyone nervous of sailing at night can find reassurance in “seeing” whats around with radar
  • Add the AIS display on the radar overlay as well. Then ships show up nicely on the image too.
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