RADAR on ships

[Crannogman]

I ran a test (of coastal guns) at Midway the other day, with a raid by a lone Yamato (because why not?) coming from the Northwest and circling the atoll clockwise.

The Yamato seemed to detect an anchored battleship fairly quickly, and indeed fixed its main guns on the Colorado-class, but did not fire. A number of destroyer in the anchorage poured a fusillade of 5" shells into the Yamato, which sailed silently by while fixed on the more distant battleship. For a while I thought Yamato was broken, until it passed between a trio of destroyers (to its port) and the atoll & battleship (to starboard). At this point, its primary and starboard secondary batteries remained trained on the battleship, but the port-side secondary came to life and quickly dispatched the destroyers.

The Colorado was the Westernmost of a line of 3 ships; easternmost was an armed trawler, and in the middle some tin can. As the Yamato drew closer, they opened up in succession from east to west (not in order of longest- to shortest-ranged guns or (presumably) optics). The Yamato and Colorado opened up about the same time (amazingly the Yamato was sunk by the 5th salvo), the first time the Yamato had fired to starboard despite multiple targets firing upon it.

So it does seems there is some other limitation on engagement range. I am using RSRDC, OTC, and ISE. Is this engagement distance hard-coded, or does it have to do with sensor and gun data that can be modified?