If I had to guess, I’d bet the boat was on auto pilot. One of the biggest things to watch for are idiot power boaters who turn on the auto pilot and then go below deck “for just a few seconds”. If you set your auto pilot and GPS to return to your slip in the marina (without using waypoints to set a path) the auto pilot will take the boat in a straight line to your destination. If there happens to be a big rock in the way, the auto pilot does not care.
That boat did not have an auto pilot
does this miracle GPS you speak of coupled to an auto pilot park you in the slip and secure all the lines too....
Your funny