[PUP] AIS pitfalls

[John Marshall]

I'm used to seeing a projected course track that extends outward from  
the target, the distance proportional to the ship's speed. At least  
that's how Furuno displays show it when using the Furuno AIS. Very  
handy, as you can graphically see where the target is going to cross  
your course line.

Not sure if all units work that way or if that would also have been  
confused by the tug.

John Marshall
N5520-Serendipity

On Jun 3, 2007, at 5:39 PM, Truelove39@aol.com wrote:

> As we proceeded up the Hudson River today, a tow hove into view   
> ahead.
> Penny, at the helm, noted that he was upbound, too. After a few   
> minutes, I looked
> up and observed that the tug was not only closer but behind  the  
> barge; he was
> in fact, downbound. A glance at the AIS display (on CE)  showed the  
> triangle
> symbol facing the wrong way! Further investigation showed  that all  
> the data
> was correct, including course, but his heading was fixed at 17   
> degrees! So we
> learned something today, fortunately not the hard way: a  simple  
> glance at
> that elongated triangle may not always tell the  truth!
>
> Regards,
>
> John
> "Seahorse"
>
>
>
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