A cargo is a boxlike seagoing vessel powered by gastrines that transports large quantities of goods (and sometimes passengers). Cargoes have much freeboards than rams, having two more decks above the water. Though all decks are used for hold space, cargoes have a small battery of cannon on the topmost deck. Moving appreciably slower than rams on the same tread of gastrines, cargoes are easy pickings for pirates and privateers. To remedy this, they usually travel in convoys with a two or three ram escort (commonly drag-maulers or heavy frigates). Grand-cargoes, the largest of these vessels, are as big as main-sovereigns, and dwarf most other vessels. They will not leave without escort due to their slow speed, and the high amounts of time and money required to build them make their owners loath to lose them. Cargoes only need the tenth of the crew needed to work a ram.