The Arcturian Fire is an inexpensive heavy weapon that has a very high chance of causing fires, of which are very potent. Additionally, this weapon deal huge impact damage to sails, as well as burning them severely, making them the strongest heavy weapon option for removing sails. Against wood, they lack much burst damage, but still cause potent fires and are still useful, although this is secondary to sail removal. Against tougher materials however, especially iron, they become far less effective. It is best to have only a few on your ship if you want to be able to destroy sails, which may be useful as a counter to faster ships and by equipping these you will greatly extend your ability to destroy them. However, against hulls, although not useless, conventional weaponry will be more effective.
These catapults lob flaming spheres of unstable plasma at enemy ships doing terrible damage to cloth sails, and starting fires on wooden ships. Arcturian Fire is considered a very primative weapon, but it can be very effective against large, slow moving ships with many sails. Of course, if you load up on these, and then encounter an Ironclad you could be in serious trouble.