I use the NASA engine, but doesnt really make any difference. Personally I prefer to view my AIS seperately from the chrt so that I dont get them confused. I use www.shipplotter.com software for the AIS. This is superb in that it works out the CPA for you and then will sound an alarm on anything coming within a defined distance/time, even if shipplotter is not the screen being viewed at the time, thus you can be looking at the chart plotter software (and I use Maxsea) and if there is a potential problem a new window pops up showing what the problem is, and an alarm sounds.
I use Franson GPSGATE software to share the gps signal between the two pieces of software.
You can chose to use a chart as the backdrop to the AIS, but I prefer a calibrated satellite image, which are available for the shiplotter .
I'm not considering AIS for myself (we don't get much commercial shipping on Lake Windermere!) but a friend is considering the SR 161 AIS engine which he has seen on a website in Canada at a much lower price than the units we see here. I said I'd gather the collective wisdom of the forum.
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How useful is AIS to you? What do you find are the main benefits?
[/ QUOTE ]IMHO I very much like the AIS used with Shipplotter software, especially when trying to cross a transit lane. It enables mean to achieve 2 things -
establish easily the visibility range.
when I am not able to cross safely ahead of a merchant ship, it enables me to manoeuvre to pass astern of ships prior to being in visual range.
It has other benefits:
It also enables me to establish ships that are not using their AIS and to prioritise those vessels for visual watch.
It does not replace radar, but does provide another very useful source of information.
If you are not used to using radar, it can assist considerably in sorting the radar picture out, and allow you to recognise if the radar is working properly.
None at all, as fishing vessels dont need to use it.
Except of course, it does allow you to concentrate on them more than you would otherwise, knowing that if one of the ones you have identified alters course to a dangerous bearing, you will get an alarm.
If you have locked MARPA onto the potentially conflicting targets you get an alarm in the same way and you can select any target, not just those equipped with AIS, or am I missing something?
I like my AIS, I have the NASA engine from a VHF splitter which works a treat. It is great at making the judgement call when you have multiple ferries bearing down on you. Normally it is hard to tell if something is going to pass in front of or behind you when it looks like it's coming right for you! Paid for itself outside Dover!
price and power consumption, and an mmsi number so that if necessary you can call a vessel directly
furthermore for marpa to work well you not only need that more expensive radar set, (= more power as well) but also a very good heading sensor (more expense).
Personally I am a great believer in keeping my systems as seperate as possible so that a single point of failure does not take the lot down