But are cannonballs any better than fireballs? Fireballs have a large spread per unit of energy and are incendiary which is very effective against soft targets such as horses and humans. A cannonball is devastating to what it hits but loses spread, and our fireballs are, I would expect, more focused on thermal energy than gunpowder is, so we end up with less kinetic energy than similar expenditure of gunpowder would provide. In short, we can already put the explosion in the enemy's face, why put it behind a rock instead? I guess that we might be able to gain efficiency bonuses from reducing the range, but then our wizards are standing next to medieval cannons...
The pulse-jet would have the advantage of being more efficient than an orion drive, which is what we can currently do with fireballs.
Which gets me thinking.
Order: Use existing freestyle crystal formation and fireball technology to put an expendable armour shell behind our ships and then use fireballs against that armour as a form of propulsion.
Orion-drive, especially if you don't have the best shaped-shield, is horribly inefficient, but it is better than mages standing on deck playing cards while the enemy is outrunning us...
Oh, and I am a bit worried that animal-people might be a bit too generic and have massive penalties. We might have to start with cat-girls to fight at night and then work our way up to mermaids and disciplined giant scorpions...