[GerritJ9]

There is a campaign available, "Hurricats", which simulates CAMship launches- not quite the real thing, but close and the maximum that was possible under FB/PF when it was not possible to mod the sim. Now, it seems anything's possible- but it would require a lot of 3D work to add a catapult to the bows of a merchantman and more work to make it function.
A shortcut as regards the 3D modelling might be using the CAMship available for SH3 once importing new objects/ships etc becomes possible, though you would, of course, require the maker's permission to use it.