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B&G Zeus 3S Plotters and Class A AIS targets

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Dave Nelson
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Joined: 6 months ago
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Hi all - wondering if others are seeing a problem I'm having and a warning to look for it...

Performed an electronics refit in late 2021, including new Zeus 3S plotters and a Vesper XB8000 Class B AIS transceiver.  After the install I loaded the latest software updates into everything, including 20.2 and 20.2.1 for the Zeus 3S plotters, issued by B&G in April and Sept 2021, respectively.  The 20.2 update included enhancements to the display of AIS Class A targets such that these would now display curved extension lines showing predicted turns based on broadcast Rate of Turn (ROT) data.  I gather that prior to this update displayed extension lines were always straight and simply updated in increments as the vessel turned.

On a cold January night moving my boat down the Chesapeake Bay, I had to talk to a container ship concerning my planned turn to avoid him in his channel and he responded he planned to turn a bit to port anyway.  No problem, but his AIS target subsequently indicated a turn to starboard.  I hailed him again and he replied he WAS turning to port.

Cutting to the chase, all Class A targets indicate they are turning to starboard whether turning to either port or starboard.  When not turning - no (or zero) ROT being broadcast - their targets indicate correctly going straight on COG.

Thus began a protracted dialogue with both B&G (Navico) and Vesper to figure out the problem.  In time (March 2022), Navico finally acknowledged they needed a software fix.  In the meantime an acquaintance reported his older Zeus plotters running 20.2 and his B&G NAIS400 AIS indicated correct Class A turns.  But I recently observed a set up with Zeus 3S plotters and a Vesper Cortex unit having the same problem as I do.

In May 2022, B&G issued software update 22.2-66.1.9 which included "improvements for extension lines from other targets" along with other fixes "from customer feedback since the last release."  After installing this update I noticed no difference in the erroneous Class A target indications.  A subsequent attempt to discuss this with B&G support has not been answered.

Since I now know that indicated Class A starboard turns could actually be to port, I'm aware of the error, but others may not be.  Some would correctly consider this a safety issue, in my view, hence this warning.

I'd appreciate any reports of seeing this problem - or not seeing this problem - along with the B&G and AIS hardware you have.


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