In RL, the IJN in 41 was very well trained and liberally supplied with excellent binoculars (up to 16x AFAIR). During the night fighting around Guadalcanal, IJN lookouts often spotted Allied ships before the IJN ships showed up on radar. At the battle of Tassafaronga, it was later estimated that the IJN lookouts had spotted the U.S. Task Force at a distance of 20-24 nautical miles, on a moonlit night. Of course, the ships they spotted were cruisers which are considerably bigger than a fleet boat.
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