Real world AIS B #3, jumping bean plots

AISB_Spirit_Bermuda_cPanbo crop

So somehow when I was actually plotting Spirit of Bermuda’s Class B AIS output in Hamilton Harbor my screen shots failed to save. But I still have the marks I made every time its plot updated and you can sort of see the jumping bean effect that results from Class B’s 30 second update rate. I connected them with route lines so you can get a better sense of scale, bigger here. As discussed earlier, a 30 knot boat is going to plot every .25 nautical miles; Spirit at 9 knots plotted at about .07 mile increments. It was a little disconcerting, especially when she made large course changes rounding up to a pier. (And, by the way, would have been twice as bad if I had been using a single-channel-at-a-time receiver). But, again, I still think Class B is valuable regardless, plus I figure some smart developer(s) is going to figure out a way to dead reckon these targets in a way that’s not confusing.
   Finally, small world department, Spirit was built only a few miles from Panbo HQ at Rockport Marine, and we watched her launch from the bridge of Shanghai Baby last August, as noted in an article just published in PMY.

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Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now excited to have Ben Stein as very able publisher, webmaster, and editing colleague. Panbo is going to the next level in 2019 and beyond.

1 Response

  1. Ben,
    I’ve automated the screen capture process using the Snagit program, available at
    Since using it I’ve never lost a capture!

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