Is it possible to flip a ship around the core?

[Jaybeanstalk]

If you say..... build your ship backwards is the only way to fix it to rebuild it block by block?

 

[Crusade]

you could copy and paste the entire ship to face the other direction.

 

[DrTarDIS]

if you're in single player, and your computer is beefy enough:
-set your build area to a large area (like half of the shortest ship dimension, or larger if you can handle it)
-dock ship to a station that has only 2 docks, (set sector to protected, or god mode, or both)
-dock 2 copies of the ship, delete in front of the core on one, behind it on the other.
-set plane in line with core, begin copy large chunk, paste it back over itself, (creates "fixed" half on paste), repeat till complete.
-repeat above on "other copy"
-choose one that was the most work, use the other as a donor
-use entity-swap arrows to copy from donor and paste onto other(remember turn off symmetry )
-do victory dance, save a blueprint backup, then go nuke the hell out of the backwards ship, vowing to forever check that arrow in the top of your screen build-mode.

 

[IG-1000]

When I was building a Space Galleon I decided that the back end looked better as a front end, fortunately it was just a frame.
So I rebuilt the thing next to the backwards one, yep I built the new one backwards because I forgot the first one was backwards, I may have built it backwards yet again I don't really recall. Needless to say it's facing the right direction now...
I should really finish that Ship

 

[Tamren Shade]

Depending on the size of the ship, you may be able to copy and paste the entire thing or, as I've had to do a few times, divide the ship into sactions and slowly copy and paste each section over. You can also use that technique to move your ship core if you decide you don't like where you put it to start out.