Okay, this is pretty obvious on one scale, because you can avoid enemy fire with a smaller ship, but note this:
I want to create a HUGE dreadnought, about 800:800 pixels. But if you think about, it won't be able to fire properly. No offset means that it's firing range is from the centre, and since the ship is longer than primary weapons range...oops.
Now, if we put the offset at the front, we can fire forwards, but not backwards.
This also leads to what I think it the Lazira/Igazra problem - why are they so long ranged? Simple. Offset at the front. Crescent Warships, I think, are actually better off turned the other way round to fire.
SilverDragon
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Metaphorically speaking, I'm metabolically challenged.