There's no mention of what happens when a player leaves the board edge. There have been a number of instances where either mine or my opponent's ship base/movement template extends beyond the boundary of the board. We've come up with a house rule (every time any part of the ship or template moves beyond the established 3x3, that ship suffers one damage) but I'm curious what the official ruling on this is.

This is actually covered in the rules. Page 17, the ships are destroyed,1

destroyed or ran away. either way in games terms its considered "destroyed" for point calculations

Not sure how we didn't see that. Does this apply to templates as well?

OhBee said:

Nope, only the final position of the ship's base matters.

Any part of the Base, is enough to apply this rule, even an smallest, I don't know how it could apply to the a combat, i think that the eath isn't plane but the galaxy yes, greettings.