For starters- Scope course is parallel to the waves so you don't get sucked up and broach. In a round bottom boat.

There might have been special scopes for early boats but I've spent a lot of time dancing with the one-eyed lady and it's difficult to keep a contact in sight nevermind getting a precise elevation angle.....

Probably WWII boats used celestial but they would have a sextant because they were really just surface craft that could disappear for awhile.