The Oberth-class is a science vessel by Starfleet. They have a very unusual structure, with two separate hulls connected by the nacelle pylons. The upper section contains the living quarters, bridge and science labs. While the bottom section contains the warp core and engineering. Either there's a turbolift shaft that runs through the pylons or the crew has to beam to each section. The ship itself only requires a small crew to operate the it.

The Oberth-class is very unusual, especially since many of the standard features found on other Starfleet vessels aren't present. The nacelles lack the normal bussard collectors and blue warp field grill. Also the navigation deflector array is missing. There might be impulse engines, but they aren't obvious.

The class was named for 20th century German rocket pioneer Hermann Oberth. The first Oberth-class ship seen was the USS Grissom in Star Trek III.

Related Links:
Size of the Oberth Class (EAS)

USS Biko NCC-50331
   Rendezvoused with the USS Enterprise NCC-1701-D on stardate 46271 at Deinonychus VII.
   Named for Steven Biko, South African civil rights activist, martyred in 1977.
   "A Fistful of Data's" - TNG.
USS Bonestell NCC-31600
   Destroyed at Wolf 359 by the Borg in 2367.
   Named for astronomical artist Chesley Bonestell.
   "The Best of Both Worlds" - TNG.
USS Cochrane NCC-59318
   Transported Doctor Bashir to Deep Space 9 in 2369.
   Named in honor of Zefram Cochrane. The registry is also believed to be NCC-8000 according to another Oberth-class vessel from "The    Drumhead" - TNG.
USS Copernicus NCC-623
   In Space Dock at the time the Enterprise-A was launched.
   "Star Trek IV: The Voyage Home"
USS Grissom NCC-638
   Destroyed in 2285 by a Klingon Bird-of-Prey at the Genesis Planet.
   Named for the Mercury astronaut Virgil I. Grissom, who was killed in the Apollo 1 fire in 1967.
   "Star Trek III: The Search for Spock"
USS Pegasus NCC-53847
   While commanded by Admiral Pressman in 2358 the Pegasus was a prototype starship used as a testbed for many of the new system    designs used on Galaxy-class ships. While testing an illegal phasing cloak the crew mutinied and only seven crewmembers escaped.    The Pegasus, while still cloaked, drifted into an asteroid not to be found until 2370.
   The Pegasus was originally planned to be a Cheyenne-class starship however it was decided to make it an Oberth-class for budget    reasons. Named after the famous winged horse of Greek mythology that sprang from the severed neck of Medusa.
   "The Pegasus" - TNG.
USS Raman NCC-29487
   Lost at Marijne VII in 2370, the crew was killed by subspace lifeforms living in the lower atmosphere of the planet.
   Named for Nobel Prize winning physicist, Sir Chandrasekhara Venkata Raman.
   "Interface" - TNG.
USS Tsiolkowsky NCC-53911
   In 2364 the crew of 80 officers became infected and died from the results of the Psi 2000 virus while monitoring the collapse of a red    super giant star into a white dwarf star.
   Named after the Russian space pioneer Konstantin Tsiolkovsky.
   "The Naked Now" - TNG.
USS Valiant NCC-20000
   Assisted in the recovery of the Enterprise-D at Veridian III.
   The name and registry are speculation for this Oberth-class vessel.
   Star Trek: Generations.
SS Vico NAR-18834
   Destroyed in 2368 while exploring a Black Cluster by the severe gravitational wavefronts amplified by the Vico's shields.
   "Hero Worship" - TNG.
USS Yosemite NCC-19002
   Severely damaged while studying the plasma streamer between a binary star in the Igo Sector in 2369.
   Named after Yosemite National Park.
   "Realm of Fear" - TNG.

Specifications:
Type: Science
Length: 150m
Crew: 80