So there you are outside one of the more sheltered harbours (Dromaan, say), unable to see how much space there is inside and wondering whether, if you go in, you’ll find you have to reverse out again. How useful it would be to be able to see inside from some distance away. How useful it would be to have a small helicopter at your disposal, one that could send pics back to you.
Clearly such a gadget would be a must-have item, an essential piece of equipment for any conscientious barge-driver. Happily, it exists.