Q&A – wireless broadband and AIS

[This is the online version of an article in the April 2011 issue of the Mainsheet, the monthly magazine of the Coastal Cruising Club of Australia]

I have recently been giving presentations about the use of the Internet at sea as well as Cruise Communications generally. Here are some of the questions which came up after those talks.

Q: Where should I install my Mobile Broadband Antenna?

A: It’s hard to be specific without more information about a particular boat, but three principles are important:

  • Transmission and reception is limited by ‘line of sight’, so install your antenna as high as practical.
  • Have it away from interfering elements. Keep it away from other antennas such as the VHF antenna (30 cm or more if possible). Don’t install it in close proximity to other metal structure (atop the mast, not next to it)
  • Install the antenna as close to the transceiver as possible, in other words, close to the mobile phone, USB dongle or Fixed Wireless Terminal (such as an Ericsson W35) you are using.
    You’ll note that there is a conflict between (1) and (3), so use low loss cable (the cable that is as thick as your thumb) for permanent installations. The “rules” for antennas are similar to VHF antennas. There is a particularly good article about antennas at boat-project.com [1]

Q: Where can I expect mobile internet reception along the East Coast of Australia and where not?
A: Australia is particularly well served by Telstra’s network. With a simple dongle style broadband modem, you will get Internet access along much of the coast of NSW and much of Queensland, with the exception of Shoalwater Bay and when blocked by Islands. As a rule of thumb, you can say that if you can see the mainland, you should have internet access and mobile phone reception. Telstra have a useful coverage map on their website [2]

Q: I have a mobile phone with Optus and I’m going to the Whitsundays this winter. What should I do?
A: Unfortunately, you’ll only have patchy coverage with Optus. Your choices are:

  • Switch to Telstra permanently, which might attract a penalty of you have to break a contract.
  • Get a prepaid plan and SIM with Telstra for the duration of your cruise. But first check that your phone is compatible with Telstra’s 850 MHz NextG network, otherwise you will still only have coverage in major centres. For the duration of your cruise, redirect your Optus calls to the Telstra number.

Q: I’ve been thinking about fitting AIS to my boat, but just found this website, marinetraffic.com which displays shipping along the East Coast. Should I bother getting the AIS unit?
A: While marinetraffic.com [3] is an interesting website to check on shipping, it is not suitable for navigation and not a substitute for having an AIS unit on board. The website relies on volunteer “observation stations” without continuous coverage of our coast and occasional long latency (the delay between transmission by the ship and display on the web page). So by all means, use it for interest, but don’t rely on it while at sea.

References:

Happy Browsing,

Marius Coomans
skipper@webcommunications.com.au