You can only kill them during SP plot missions or with mods, stationary Battleships that act as bases in an unmodded game are invincible.

-----------------------------------------------------------
"The worst player has guns, and grenades, and vehicles, and all manner of damaging tools. Like a baby with a razor blade, he need not be skilled at all with his tools to cause terrible damage with them; a blind man can fire a tank and kill you."

--7--

there are modded server with battleships flying around in multiplayer. One is called Yukanojo's Universe.
This is the Server website:
http://undernet.game-server.cc:1001/fl/

This is the server forum:
http://theboneyard.proboards30.com/index.cgi

You know what?
You guys should populate
Yukanojo's Server.
I love it. Start out completely neutral and 5k credits. Also, you can e-mail me and ask to join my clan if you want. I have 2 members already. If I agree with you joining, meet me at manhatten and i will give you 100k credits. So, pay a visit to Yukanojo's server. Also, during the next week(10th to 16th), I will be donating my 7-8mil credits, and equipment to someone on the
[5thW FL:: www.5thss.com
server to some lucky player hanging out manahtten. I wil be around manhatten and only for 5 mins. I have kusari rare guns all the way to nomad guns and level 10 fighter shield. Don't miss out.