[Zorin]

Well, the hull of a regular merchant ship wasn't like "thick". I'm sure that spending lots of 50cal or 20mm rounds (IRL), will punch enough holes in it to make it sink as well. Cause in the end, the ship sinks because it is leaked, not because it is blown apart. That only happened if the cargo was of the explosive kind or the fuel storage was hit.

So all the rocket do is make a big hole.