Shipboard Catapult Weight - inclusive/exclusive of Cargo?

Is the weight of the catapults or whatnot that can be placed on galleys inclusive or exclusive of the cargo capacity?

In other words, can I leave off the two light catapults on a Small Galley and load 240 more stone of cargo, or does adding the catapults reduce my capacity by the same?

I’ve always treated them as entirely separate. The encumbrance or weight of the catapults is relatively irrelevant to the cargo capacity and vice versa. It’s more a question of bulk, space, and rigging.