This morning, I did some testing on naval models by replacing the Ironclad model (used by the dreadnoughts, pre-dreadnoughts and battlecruisers) with the 38-gun Steam Ship model (used by cargo ships).
The game did not crash, and I was able to load the battle succesfully. As you can see in the attached picture, the model of the ship is, quite amazingly, that of the 38-gun Steam Ship. This means that it is possible to switch models on the ships.
Furthermore, having a rigging (found in the logic.xml.rigging) apparently unrelated to the model (which is the case here, the masts are obviously too big and are floating above the ship model) will not cause CTDs. This is obviously a good thing, since we don't want our World War I-era ships to have sails like those ships of the line from the 19th and 18th century.
Lastly - and this might be a problem - you can clearly see that the guns and the crew are misplaced. In fact, they have kept their Ironclad position and deck structure, and this is something that I believe is unrelated to the rigging. The problem with this is that it means that we have to identify the file(s) responsible for the cannon and crew positioning, but at least changing models will not cause a (CTD) conflict.
- Aanker, Chief of the Experimental Department