Port Watch

taken, of course, during the first dog watch.

Etymology ? Wikipedia has the details:
Dog watch, in marine or naval terminology, is a watch, a period of work duty or a work shift, between 1600 and 2000 (4pm and 8pm). This period is split into two, with the first dog watch from 1600 to 1800 (4pm to 6pm) and the second dog watch from 1800 to 2000 (6pm to 8pm). Each of these watches are half the length of a standard watch.
The name is said to derive from Sirius, the "Dog Star", on the claim that Sirius the first star to come into view on the first dog watch. In fact, however, the time of the rising of Sirius varies with the time of year, so that for six months of the year it is below the horizon at sunset. Moreover, the first dog watch (1600-1800) is typically in daylight, and the stars are not visible. An alternative folk etymology is that the name arose because someone tasked with one of these 'half' watches was said to be 'dodging the watch', taking or standing the 'dodge watch'. This became shortened to 'dog watch'. Another variation is that those sleeping get only 'dog sleep' in this watch. Stephen Maturin of Patrick O'Brian's Aubrey-Maturin series makes the pun that the dog watch is so-named because it is "cur-tailed" ("curtailed", i.e. shortened).
The reason behind this watch's existence is that in order for the crew to rotate through all the watches it was necessary to split one of the watches in half, to create an odd number of watches in a ship's day. This allowed the sailors to stand different watches instead of one team being forced to stand the mid-watch every night. The choice of time also allows both watches, if there are only two, to eat an evening meal at about the traditional time.