[PUP] AIS Transponder

[John Marshall]

I often see AIS targets on the Furuno come up at long range with only  
an MMSI number. No name.  As the distance closes, the quality of the  
data exchange seems to improve (my theory) resulting in catching the  
less frequently broadcast messages. I think its just that parts of  
the message get garbled when the target is too far away.

After having used AIS in the traffic lanes of LA, SF and the Straits  
of Juan de Fuca, and shooting the Admiralty Inlet going down into  
Puget sound today with lots of large, fast traffic, I swear by the  
system.  It might still get crowded out there, and a bit tense when  
you can't see, but watching CPA's and the projected tracks on the  
screens is sure reassuring. Plus VTS traffic control sees us and when  
ships call in to enter/exit an area, we often hear our boat's name  
being mentioned in the traffic briefings. Nice to know everyone else  
knows we're out there.

Too bad Naval and CG ships don't generally broadcast their position  
(although for understandable reasons). That lack has led to a tense  
moment or two in thick traffic when a big radar target doesn't have  
any AIS data.

The big gripe is that smaller vessels don't have it. I'm hoping the  
marine model will follow the aviation one where transponders are  
pretty much required for everyone... eventually.

John Marshall
Nordhavn 5520 - Serendipity

On Jun 1, 2007, at 5:58 PM, Dave Cooper wrote:

> <Steve wrote: So, it is common to see vessels
> without their names for a while.  Did they wait long enough?>
>
> This is a known but not publicly announced problem as near as I can  
> tell
> with the Class A AIS units. The software needs to be updated to  
> include the
> vessel types.
>
> There are, I believe 80 types of which only something like 20 are  
> currently
> used. The unassigned ones, as they become assigned will need to be  
> input to
> each users system via an upgrade as I understand it. This doesn't  
> sound like
> the best situation but again this AIS system is a developing one,  
> IMHO, even
> tho it is deployed and mandated on over 300 ton vessels and all  
> passenger
> carrying vessels on international voyages.
>
> They had several hours to acquire our name....all our other data  
> was there
> from the get go they said.
>
> Steve, do you have an AIS? If so what make?
>
> Cheers
>
> Dave & Nancy
> Swan Song
> Roughwater 58
> Caribbean Cruise '07
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