Chartplotter with AIS overlay ?

[captainslarty]

Hello all.
I am thinking of buying a class B transponder (AIS) and need to consider a chart plotter that allows AIS data overlay.
I would prefer Navionics charts.
Which plotters that you know of can overlay this data ?
I like lowrance and was considering the 8200, but does not seem to have this function, and my current 3500 certainly doesnt lol.
Dont want to really pay raymarine prices.
Any ideas please ?
ps, a laptop is out of the question. I already have one but do not want it running all the time)
ta.
Joe

 

[pvb]

If you want AIS overlay on Navionics charts, your choice is basically restricted to Raymarine. If you'll accept C-Map charts, the choice is wider. For example, the Standard Horizon CP300 at around £500 supports AIS and has a 7" 800x480 screen, or for £1170 the Standard Horizon CP500 has a 12" 800x600 screen. The Northstar/Navman ranges have an 8" 800x600 display for around £1070. The Siewa Starfish has a 7" 800x480 display for around £850.

Not sure whether an AIS transponder is really worth it.

 

[captainslarty]

Many thanks PVB.. appreciated... !
Why not a class B ts ?
I think its another weapon in the anti collision armoury
Joe

 

[pvb]

I don't think ships will necessarily pay a lot of attention to class B AIS. Worse than that, if lots of people start fitting them it will be a problem on leisure chartplotters - most will only display a max of 100 AIS targets, and usually they choose the nearest. So the screen will fill up with relatively unimportant targets.

 

[captainslarty]

Yes, good points, However, I am taking offshore. I didnt think there was any differentiation for the ship 'tween A n B ???
Joe

 

[pvb]

[ QUOTE ]
I didnt think there was any differentiation for the ship 'tween A n B ???

[/ QUOTE ]The AIS equipment on ships differs widely. Some can certainly differentiate between Class A and Class B transmissions. But the situation is much more complex. Don’t run away with the idea that, just because you have a Class B transponder, ships will automatically notice your presence. Right now, ships only have to have what’s called a "minimum keyboard and display". A simple alphanumeric list, which need show no more than three ships at any one time (and only detailing bearing, range and name of ship) meets the minimum requirement! Even ships which have some sort of spatial display of AIS targets often revert to a text list because the graphical display becomes so cluttered.

Remember too that the AIS system on many ships is a stand-alone device which is not integrated with the rest of the navigational suite. There’s no requirement for AIS to be integrated with the radar display until July 2008 and even then the requirement will only apply to <u>new</u> ships and to <u>new</u> radar sets. It won’t apply to repaired radar systems. And, of course, the minimum keyboard and display may not be under continual observation.

Andy Norris of the University of Nottingham, writing in the Journal of Navigation, said “The CSTDMA Class B system has been designed to prevent overloading of the AIS VHF data link. This is briefly reviewed but there are a number of other aspects that need to be considered. These include: the increased garbling of Class B messages compared to those of Class A; the problems accruing from the low update rate of Class B information; the increase in display information that will need to be managed; and the possible increase in inappropriate manoeuvres of leisure craft caused by misplaced reliance on AIS. As a result of the investigation the paper highlights the fact that Class B users must not assume that their own presence, in the form of Class B transmissions, will be particularly visible on the bridge of many SOLAS vessels. This will continue to be the case for many years into the future, until such vessels are mandated to carry radar with AIS target overlay capability.”

Unfortunately, if there’s a proliferation of Class B transponders, the situation will get potentially so confusing that action will need to be taken. One result might be that Class B signals simply get filtered out. In the present regulations there is no need for Class A stand-alone equipment to have any filtering capability. On a radar screen an excessive number of AIS symbols will make the observation of raw radar data more difficult and so the display of AIS targets may need to be inhibited or an AIS target filter enabled. From July 2008 all new navigation displays capable of showing AIS targets will need to meet the requirements of IMO's “Performance Standards for the Presentation of Navigation-related information on shipborne navigational displays”. As with the new radar standard, AIS filters must be included “in order to ensure that the clarity of the total presentation is not substantially impaired”. That sounds to me like they’ve paved the way for Class B signals to be excluded from the display when things get busy.

So, I’m not convinced that a Class B transponder is a cost-effective purchase.

 

[Gelfi]

Spoke to the Lowrance rep at Excell and was told that a software download for both new and slightly older models would be available some time this year. Lowrance appear to have the best displays and use both Navionic and there own charts.

 

[pvb]

[ QUOTE ]
Lowrance appear to have the best displays .....

[/ QUOTE ]I don't think Lowrance displays are any better than comparable spec ones from other plotters. But you're proving that screen definition is important - Lowrance routinely use higher-definition screens. More pixels mean sharper images, better text, smoother graphics. When Lowrance have proved the importance of higher definition, why do so many plotters still have clunky 320x240 screens? And the Lowrance 5150C, with a 640x480 screen and a NauticPath chart, must be the all-time bargain for under £300!