Have you looked at tug boat propulsion units lately? Those things look like black magic.

You are right, these things are nuts: https://en.wikipedia.org/wiki/Voith_Schneider_Propeller

Wow this is the coolest thing I've learned this week.

I'd guess figuring out where you can safely attach the tug boats, monitoring stability and stresses on the container ship and so on is non-trivial, too.

If you fuck up bad enough those containers end up landing on the tugs, killing the crews. Not to mention increasing the quantity of stuff blocking the canal.