It is May '42. I graduated out of my S-class and into a Salmon and headed to Rabaul harbor, one of my favorite "haunts" for sniping motionless IJN ships. As usual there is a monitor in the outer harbor (and new to me, maybe the mod setup I'm using, ALSO one in the inner harbor).
In the past I had found I could slip past the outer guy by hugging the southwest shore and keeping it slow and quiet. This time I figured I'd try something different.
So I spent a good 2 to 4 hours in game time (and probably an hour in real life) crawling along across the deep part of the outer harbor from NE to SW ish and using my sonar ray marker to plot approximately where he was every couple minutes. This was only mildly tedious at 8 TC speed.
This is what I came up with
Having now positioned myself at the point in the shallows just east of the small promontory on the south shore (there is a circle and some lines there) to setup a shot at him with an Mk 14 (or 8 . . .) I've watched him do a full lap at least 5 times and he never deviates from it.
It may be the exact coordinates of his route are not identical each time, it is impossible to say with certainty just based on any available in-game information, but he is DEFINITELY sticking to one route.
This is the downside of learning C++ and a bit about how games work

!
You realize how challenging it is to create bug-proof ANYTHING, and so how the best "solution" to creating the illusion of "intelligent" computer opponents is often to "cheat!"