Eyeballs cannot be hacked. Who or what was on watch?
Hacking the binocs of the Swabbies on watch would be a trick. Not like they were keeping eyes peeled for a car on a tree lined Street or something.
The crow's nest on a ship was so called because crows were often taken on board to help the navigator determine where the closest land lay. In cases of poor visibility a crow was released & the navigator plotted a course that matched the bird's because it invariably headed towards land, 'as the crow flies'. The crows' cages were kept high in the main mast where the look-out stood his watch.