Class-4 stardrive vessel was the designation for a type of small 23rd century spaceship, utilized by the Federation Merchant Service for the role of survey vessel. This class of vessel was equipped with transporters and utilized iridium in its construction. The SS Beagle was a vessel of this type, it had a crew of 47, and was in service until its destruction in 2262. (TOS: "Bread and Circuses" )