Dry goods freighter and tanker, by Jay Thurman (human)
Freighters (freight transports) are the most common type of spaceship in the Frontier. They are built in a greater variety of styles than spaceliners (hull size 5-20) or other ship types. The largest are as big as a battleship, but are much slower and less maneuverable. Some small freighters are fast enough to outrun pirate vessels or spacefleet frigates. Most of the room in a freighter is taken up by cargo, so the crew area will generally be vary minimal. Some are armed with minor defensive armaments to ward off pirate attacks. Some will require an overhaul after a single jump, while others will be able to make 8 or 12 interstellar trips or more without maintenance.
These are the most common types of freight transports:
Fast freighters (hull size = 3-4), also known as couriers, are commercial starships generally employed in frequent runs, such as delivering supplies to outposts and bases, or occasional runs of low-bulk cargo, such as heavy machinery or high-tech parts. Fast freighter often carry some minor defensive armament.
Hauler (hull size = 3-4) are space-going tugs that drags heavy, non-powered loads and modular cargo containers, though they have precious little cargo space of their own. Haulers are fitted with big power plants and huge engines, at the expense of crew quarters and armaments. They are like semi trucks in space.
Bulk freighters (hull size = 5-14) usually carry cargo in bulk containers, and carry out regular runs between densely populated systems. Hull Size 5 and 12 are of the most common sizes of this class of freighter.
Tankers (hull size = 5-14) are more specialized freighters, that are intended to transport large quantities of gases or liquids. Although these ships can be adapted for other forms of cargo storage, most ships of this type carry water, hydrogen, petrochemicals, or oxygen.
Heavy transports (hull size = 15-20) are designed to move great amounts of specialized cargo such as bulk freight, containerized freight, or roll-on/roll-off vehicle storage.
Freight hauling is a stable and lucrative trade. Hauling "high risk" materials can be very lucrative. Because of the valuable cargo ferried by freighters, they are usually at risk of piracy.
(Material based on official rulebooks, and D20 Future)