Interaction seems pretty clear if I'm driving a ship with Montferrat and *I* ('you' on the card text) overlap another ship - he goes away, then.

When if another ship hits the ship Montferrat is on? Did ' overlap' in that case? Or, since the enemy ship cannot complete its maneuver if it would overlap, and backs up until its not...am I in the clear?

The wording is "After you execute a Maneuver".

If someone rams into you, you were not executing a Maneuver.

So it doesn't apply.