Our trip in "real-time"

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Sunday, July 7, 2013

Automatic Identification System


Pam and I are enroute from South Haven to White Lake Michigan.  This is a 59 nm leg.  Our plan is to come in to White Lake and anchor for the night.  Along the western shore of Michigan several lakes have had natural channels deepened or manmade channels dug to provide access from the big Lake Michigan to smaller lakes along the shore.  This makes for great places to duck in to if the weather turns bad, or provides scenic places for cruisers to harbor in.  We are making White Lake a one night stop over and then heading to Frankfort, Michigan to spend a few days. 
Although Pam and I both enjoy night sails it can be tiring.  During night sails we take turns on three hour shifts.  When ‘on shift’ the person has responsibility for navigation and collision avoidance.  The person not on watch has a responsibility too – to rest.  So if not on watch good seamanship has you sleeping so you will be prepared when the watch turns over.

Pam mentioned in an earlier post that we had an Automatic Identification System, AIS, installed just before leaving Chicago.  These systems use digital radio signals to exchange information between boats, some shore based stations, or aids to navigation through a specific radio frequency. 
There are three types of AIS:  Receiver only, Class B, and Class A.  The receiver only receives the messages sent out from boats carrying Class A or B transceivers, land based stations or aids to navigation.  The Class B AIS is a transceiver, meaning it both receives and transmits certain information about the boat.  These are not for commercial ships so the information transmitted at slower intervals and is limited in content.  Finally there is the Class A AIS used by commercial boats.   Commercial vessels are required to have AIS installed, although there is no regulation that requires it be in working order.  These transmit the more detailed information at more frequent intervals than the class B.  Class B transmits the information every 30 seconds, assuming the boat is moving a minimum of 2 knots.  The Class A transmits every 10 seconds or less depending how fast the boat is moving. 

The type of information transmitted by Class B boats include:  Ship’s name, type of vessel, call sign, size, course and speed.  Class A AIS includes additional information such as cargo information and destination.

As Pam mentioned boats to receive AIS signals may set a ‘ring of protection’ so that an alarm sounds off when a boat transmitting an AIS signal breaches a predetermined range.  We have our range set to sound off for any AIS boat that enters within a one mile zone.   
If you want to check out what AIS might look like and the type of information we receive while sailing, check out MarineTraffic.com at  http://www.marinetraffic.com/ais/

Fair winds,

Jeff   

5 comments:

  1. Just wanted to let you guys know that I bookmarked both your sites, this and the one with your location. Looks like you made a nice sail to Frankfort. Stop and drop anchor for lunch in front of sleeping bear dunes, have a beer and take a picture for me. I ALWAYS wanted to get to that shoreline, but crossing on foot was too daunting. Then try to take in Leland. It's a really cute spot.

    Have fun. I'll be keeping a weather eye out for you :)

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  2. Been tracking you on the map. Really cool! Have fun and smooth sailing.

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  3. They've had this type of technology for a while now, but this device, the Inreach SE, is the latest and greatest in that you can actually send and receive messages via GPS. No cellular or WIFI needed. It can also be used anywhere, like for hiking, camping etc. Definitely feel a little safer with it as people know where we are.

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  4. Yes it is - looks like you're tucked into S. Manitou Island for the evening.

    That's got to be somewhat isolated - enjoy!

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  5. Indeed, nice and peaceful. There's five other boats anchored here. However still getting a cellular signal, probably from Leland, so not that isolated!

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