Friday, July 7, 2017

AIS


In the you-can-never-have-enough-information category, I am including the newly purchased AIS. No, it’s not misspelt, it is AIS, as in Automated Identification System. It came packaged in a Standard Horizon VHF radio. The Matrix AIS/GPS GX2200 to be precise. This marvel of technology has a VHF radio, GPS, compass, rudimentary but quite useable navigation abilities, and AIS. There is more, like a foghorn and a hailer but I do not want to be a bore.

For some background on AIS, working vessels are required to transmit their name, location, heading, and speed on a near constant time frame, and this is what AIS does using VHF frequencies. Depending on how a boat is equipped, it can transmit its own information and receive others, or just receive other transmitting boat’s data. The latter is what Carrie Rose chooses to do.

A VHF (very high frequency) radio is how boats communicate. There are specific channels for specific functions. Channel 16 is for emergencies and to be monitored at all times. Channel 9 is for calling other boats, though this often falls to 16. Channel 13 is for ship to ship or ship to bridge. The channels run into the 80’s and then there are 10 channels devoted to weather forecast.

In what I believe to be a remarkably simple solution for the government, they decided to use a radio signal, not some exotic space technology thus the price for an AIS devise is reasonable, and no complicated hardware is needed. For AIS to work all that is needed is power and an antenna.

Carrie Rose has always had two VHF radios that is until last year when the older of the two finally died. The AIS/GPS function added about 150 dollars to the cost of a plain radio, which in terms of “boat bucks” is a tolerable hit, that is if the AIS proves useful.

The first several cruises from Herrington Harbor South, where I installed it, to the Magothy and Chester Rivers and then to Rock Hall did not highlight its usefulness. I was beginning to doubt the expenditure. Then from Rock Hall to the Sassafras River, and onto Havre de Grace and the C&D Canal, the added information helped make the trips less demanding.

The northern portions of the Chesapeake are confined. We travelled closer, if not in, the large ship channel and crossed it several times once during a thunderstorm where the rain severely curtailed visibility. In the distance, I could see large tows (tugs pushing barges). Their speed and direction are the concern. If close enough, radar is a good way to keep track of them but now with the AIS, while many miles away I could see the little circle with a line pointing to their direction in relation to us.

I cued up the AIS screen and picked my target. There was the speed and direction. Though we were headed to the same place — the entrance of the C&D Canal — our speed was 7.1 knots and theirs was 6.8. I relaxed. Carrie Rose would slowly gain distance and be anchored in Chesapeake City without interference from the behemoth.

I would have easily dealt with this in pre AIS times, but by taking the guesswork out of the navigational question, it took the stress out. A simple thing this marvel, a couple of data points broadcast over Marconi’s wireless telegraphy.




1 comment:

Adventures of Fran and Stephen said...

I too love my AIS. It is amazing technology and it gives you another toy to use underway to keep you alert.
Cheers
Stephen