Would the stern swing to port?

What?? I have been researching the so called "Gross tonnage rule" and from a Coast Guard Auxiliary site I read:

"In other words, if a boat is moving a 5 mph east and you were in the vacuum of space, it would never stop traveling east at 5 mph. However, we all know when we stop our engine on our boat, we slow down".

I wonder if I was in the vacuum of space and I backed the engine would the ship and the propeller begin to rotate in opposite directions? I mean assuming my engine is going to run?

Anyway speaking of ships in outer space the blog Strait of Magellan has safely circumnavigated the sun.

K.C.