Fubar512 1,350 Posted August 17, 2017 Anyone care to guess what caused the return at the 8 o'clock position on this commercial marine radar display? It's on a 12-mile range setting, so each ring represents 3 miles across. That places the target 4.5-5 nm out from the vessel carrying the radar. Now, I know what it is, from its track (relative to the antenna's sweep period), and by having encountered such targets before. Share this post Link to post Share on other sites
Skyviper 1,101 Posted August 17, 2017 No guesses here. I thought I was looking at a weather radar for a second :/. But you do have me interested. Share this post Link to post Share on other sites
+Crusader 2,101 Posted August 17, 2017 DDG1000 .. and you are able to see the boat with the $ 10 commercial radar.... Share this post Link to post Share on other sites
Fubar512 1,350 Posted August 17, 2017 Skyviper, you are correct in one respect. You are looking at a heavy rain storm approaching from the vessel's port side. I happen to know that this boat is tied up at its slip in a small marina. Notice the diagonal line near the center of the display ? That's the land and docks in that marina, and in the surrounding area. The target at 8 o'clock traces back from a thin line and then gets "thicker" as it goes along. The antenna sweeps every 3-4 seconds. To make a line like that at that distance (given the sweep interval) requires a bit of headway. Hint: It's not another vessel. Share this post Link to post Share on other sites
+76.IAP-Blackbird 3,557 Posted August 17, 2017 It`s a girl!!! Congrats! Share this post Link to post Share on other sites
Skyviper 1,101 Posted August 17, 2017 If that's rain, then that really thick mass seems like a bow echo. My guess is that it's a waterspout. Share this post Link to post Share on other sites
Fubar512 1,350 Posted August 18, 2017 It's an aircraft. Share this post Link to post Share on other sites
+swambast 723 Posted August 18, 2017 OK Ed, I'll bite...F-18 or F-35? Share this post Link to post Share on other sites
Fubar512 1,350 Posted August 18, 2017 An airliner from the size of the return. Too bad it wasn't a video, as opposed to a still, then you'd appreciate how fast the return traverses the display. Share this post Link to post Share on other sites
Skyviper 1,101 Posted August 18, 2017 Well. That makes sense. So how high or low was it? Share this post Link to post Share on other sites
Fubar512 1,350 Posted August 18, 2017 1 hour ago, Skyviper said: Well. That makes sense. So how high or low was it? To figure that out, one must know the height of the radar, how its mounted (savvy installers place a wedge under the mounting flange to compensate for a boat's running angle), and the vertical beam width (large span open array radar antennas usually have a narrower beam width, than smaller, enclosed dome antennas). One boat that I used to run had a 72-mile radar mounted on it's bridge top. The antenna was about 20 feet above the waterline. On its 12-mile range setting, I used to see smaller, private aircraft departing from a local airport about 6-7 nautical miles away, and at the 36-mile range setting, military transports climbing out of joint base McGuire -Dix-Lakehurst (once they cleared the ground clutter). Share this post Link to post Share on other sites
Wrench 9,855 Posted August 18, 2017 and here I was going to say "the Hindenburg".... Share this post Link to post Share on other sites
