[PUP] More AIS

[John Marshall]

<Dave> To your question, I have the Furuno Class A AIS.

The base stations have a name, not just an MMSI, but I haven't  
bothered to scroll through all the data to see what I can learn. I  
tend to ignore them... not sure what to with them, other than perhaps  
as a fourth level of navigation backup.  I'll check to see what info  
is on the fixed station pages next time I fire up the AIS.

Lately, I've been getting fixed stations and ships at such distances  
that I've had Nobeltec filter the targets to only track ships within  
20 miles of me. Before filtering, I had over a eighty targets  
(Straits of Juan de Fuca) with the furthest ones at 80+ miles. No  
data at that range other than location, SOG and MMSI, but the system  
was still diligently tracking them. Good thing I have a high-end  
desktop computer to run Nobeltec.

As more transceivers are sold, filtering is going to be a real issue.

It would be nice if ENav vendors gave us some options. For instance,  
I'd like to know when those 32+ knot ferries are coming when they're  
still 30 or so miles out. 20 knot freighters at 20 miles is cool.   
8-10 knot trawlers and tugs at 10 miles is good.

I guess what I'm hoping for is a Time to CPA filter capability. That  
would let me sort out risks by required decision time, not just by  
distance.

Also different symbols on the screen for different ship types. Tugs  
with long tows are a particular concern up here. I spend a lot of  
time scrolling through the screens to sort out the tugs with short or  
long tow (AIS shows the tug, not the tow way behind it) and making  
crossing decisions accordingly.

On the other hand, it gives me something to do as the autopilot  
drives. Guess I shouldn't complain.

Last point... its easy to get complacent watching the shipping lanes  
via an AIS overlay on Nobelec. It looks so orderly, seeing those AIS  
targets marching up and down the lanes on the map, and making  
crossing decisions based on that. Well, today, I got closer than I'd  
like to a very big Navy warship screaming down the shipping lane at  
nearly 30 knots. No AIS. I realized I was depending too much on the  
wonder box to show me the big boys.

(For some strange reason, CG and Navy ships don't advertise their  
positions. <wink>)

John Marshall
N5520-Serendipity


On Aug 10, 2007, at 12:43 PM, Dave Cooper wrote:

> <John wrote: I've seen a number of things that report as "Base  
> Stations" on
> AIS.  Not sure it that's an ATON. I've seen them at ranges out to  
> 60 miles.>
>
> If I recall you have a Furuno AIS. Is this true or is my CRS acting up
> again?
>
> We have been told that these AIS units may be replacing lighthouses  
> if they
> are on land and leading sea buoys if they are in the water. How  
> much of this
> is true seems to be hard to find out.
>
> In the UK there are many many of these "base stations". More to follow
> according to a UL friend of mine. The new "smart buoys" will be  
> equipped
> with SIS transmitters to help their identification and also as an  
> ATON.
>
> Coastal Explorer only identifies them as "base stations" with their  
> MMSI
> numbers, location and accuracy of location. I have an earlier  
> version of the
> Captn which does a similar readout, Sea Clear also. Sure would be  
> nice if
> the software computed the range, bearing, CPA, etc as it does on  
> ships.
>
> I can see lots of great uses for all of this....looks like the  
> software
> folks have to catch up with it.
>
> Cheers
>
> Dave & Nancy
> Swan Song
> Roughwater 58
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