Just an FYI...
I tried to add some new cannons to a couple different ships, just as a test. Used TOOL, edit scene, added cannon_x.gm, rotated model to fit, played around with correct placement coordinates on the hull, then added cannon locators for the new cannons, and saved the GM model (ship hull). File sizes were smaller (depending upon the number of cannons added) - and it appears that the collision data might be missing.
Everything looks OK in TOOL and in GM_Viewer, i.e., I can see the new cannons added.
I tested the modified ships in game, and got the dreaded BEEP. The ship is playable and all the added cannons actually fire. And the ship(s) did not cause a CTD.
I also, got this error message in sytem.log:
<!--c1--><div class='codetop'>CODE</div><div class='codemain'><!--ec1-->SHIP: Down trace error, ship XebecSS<!--c2--></div><!--ec2-->
<a href="http://www.picsaway.com/view/xebecss_addedcannons-2bc461b143.jpg" target="_blank"><img src="http://www.picsaway.com/thumbs/xebecss_addedcannons-2bc461b143.jpg" border="0" class="linked-image" /></a>
So, it looks like either I did some part of the process wrong, or TOOL craps out on adding individual cannon GM models to an existing ship GM model. And, as the help files for TOOL mention, I suspect that the missing info is the collision data.
EDIT:
I just re-read a couple of the posts above, and I guess I don't quite understand how to add the cannon(s) ONLY as a locator and not to the hull...
kevin