Hi Michael,
Very neat solution to the AIS issue. And for only 25 Euros (approx $33, U.S. dollars), it looks like a good program.

I have to read the website more carefully, in order to fully understand its limitations. It does mean that you have to be running your laptop (or Pocket PC).

There are several alternate solutions:
1) The SR161 AIS receiver - $189. Uses a simple VHF antenna. A dedicated single channel receiver with output at 38,400 baud (standard for AIS). That will feed directly into many of the newer generation Chartplotters, including Standard Horizon, Simrad, etc. Garmin was slow about this, and they now support it. If you have a Standard Horizon 155, 175 or 1000, they can be updated at no cost using a firmware chip the company mails to you. (You pay only postage). You can also download a software package "Seaclear II" - completely free, and good software that allows reading raster charts, navigating with GPS input, and displays lots of info about the vessels on the AIS. I plugged a USB port GPS into a USB port on my computer, and fed the AIS receiver into a serial port. Worked beautifully, and does a great job reading contiguous charts.

2) There is a complete LCD display unit made by a company based in England, called NASA (no relationship to the U.S. Space Agency), and marketed in the U.S. by Simrad. About $400. But shows a small display LCD that shows the location of all vessels up to 30 miles away, as well as all the usual info typical of AIS.

3) There are a bunch of even more pricey units in the thousands, but those often include a transponder.

I hooked the Milltech SR161 to our new Standard Horizon 180i chartplotter. Works like a dream. Not only do I see the freighter looming above me and about to crush us, but if I doubt that, I can look at our chartplotter and it will tell me the call signal, name of the vessel, SOG, CPA (closest point of approach) and Time to CPA (TCPA). That will confirm in digital terms that we are about to be crushed by a 768 foot freighter going at 15.32 knots, and will collide with us in exactly 1minute and 22.5 seconds!

If I want more data, I can go below tyo the nav station and check it all out on the laptop, and confirm the beam, draft of the vessel, and its destination after it runs us over. (Oh, as we were on our way to Panama, we crushed this really cute little double ender. Hmm! Looked like a Perry design. )

We like it, but haven't had to use it in the heat of battle. I think that it's real value will be in crossing shipping lanes, especially at night. Very important supplement to radar, and some are now saying that for purposes of shipping lanes, it may even be more important. But remember that warships are generally exempt from the requirement. Don't expect that Stealth High Speed CIA vessel to provide a strong signal telling you that you are being tracked, etc.

My argument in favor of having the info on the chartplotter is that I have it at the helm, and don't have to dash below to check the laptop. I also have the chartplotter wired in a manner that allows me to move it from the cockpit down to the nav station, where is also automatically connects with the AIS receiver. Thus, if I am below preparing something to eat, I can keep an eye on the chartplotter and AIS.

My guess is that the next generation of chartplotters that already are integrated with a VHF (e.g., the newest line of Standard Horizon), will add an AIS decoder into the same unit. The extra cost at the time of manufacturing is purely that of programming the receiver and add a small demodulation circuit.

No, I don't work for Standard Horizon, but I do have a bunch of their gear because of their technological sophistication and reasonable prices.
regards,
Harvey

  ----- Original Message -----
  From: Michael Kramer
  To: baba net
  Sent: Wednesday, February 21, 2007 10:32 AM
  Subject: [Baba-L] AIS plotting

  Late follow up on the AIS thing, which is all new to us. Found a URL advertising a plotting program which runs on PC and one´s already installed VHF receiver (Channels 87 or 88). We have a couple of idle multiband receivers on our HF sets which can be used to monitor these channels, so it sounds feasible . Also no extra hardware to import (smuggle) into a foreign country, The site is:
  http://www.coaa.co.uk/shipplotter.htm
  Would appreciate comments about this.
  Michael and Elizabeth
  S/V Cambria
  La Paz, Baja

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Received on Wed Feb 21 11:13:07 2007