ORIGINAL: Yamato hugger
Well thats not always true with subs. The Barb for example used to raise its periscope and observe a target while they maneuvered to get in front of it thus staying over the targets horizon. Makes sense that they would probably use that method (periodically if nothing else) to spot as well, so that would increase the observation range a lot.
I think this was referred to as 'high periscope watch'. IIRC, aboard O'Kane's Tang they welded small platforms to the periscope shears on which lookouts could stand, thereby giving a few additional feet of altitude to enhance the spotting range.










