Thanks Maxi for the explanation.

Hello Matty anda David.
The main reason to drop the anchor is for manouvering auxiliary. While the ship is moored, it doesn´t do anything.
As tugs are not compulsory, in most Parana Rivers Port the anchor is use for "hold" the bow when mooring, like a bow thruster.
And when the ship departure, heaving up the anchor in adtion to the river current, helps to open the bow from the pier.
Basically it act as a "free" tug or non mechanical bow thruster.
Best regards
Maxi

Thanks David, yes I see.

Seems to be standard practice there
http://www.shipspotting.com/gallery/photo.php?lid=3123840
http://www.shipspotting.com/gallery/photo.php?lid=3123480
http://www.shipspotting.com/gallery/photo.php?lid=3123476
etc

Dusty work. But why drop anchor on a secured berth ?