alpena
Re: alpena
...and as a partial answer to the first question, the Alpena stops at Calumet Superior fuels in Duluth almost if not every time she visits the Twin Ports, so there's part of the picture but probably not all of it.
Re: alpena
AIS information on any public site depends on people with access to AIS systems deciding to contribute information to public networks. Coverage on public sites is far from complete and often changes as people start and stop transmitting AIS info. within range of their system's receiver. Sites like boatnerd.com's appear to do a great job of consolidating different feeds, but ships will still go out of range of all contributors' receivers from time to time and will 'disappear' from public site view. This doesn't usually mean a ship is turning off their AIS, nor does it usually mean a ship's transceiver is particularly weak, although their strengths probably vary a bit from ship to ship. Environmental factors also likely play a huge role in the transmission range of AIS info. from one ship vs. another.