Canon facts Backstage Info  Speculation

Notes : The Shelley was originally designed in the 2280's as a transwarp-capable cargo carrier which would replace virtually every large cargo vessel then in service. The ship was developed in parallel with the Excelsior class, and was essentially a heavily modified version of that vessel. The saucer section gutted of all science and diplomatic facilities, most of the crew quarters and the weapons systems. The space freed up was used to install the new transwarp power core and supporting machinery, with a pair of nacelles attached directly to the saucer outboard to port and starboard. The neck section was also retained, but the engineering hull was removed entirely from the basic design to be replaced by any one of several types of modular cargo carriers which were designed.

The Shelley would be by far the fastest support craft ever fielded, giving Starfleet great power and flexibility in its ability to deploy large cargos within and beyond its own borders. Unfortunately, the transwarp drive which was the heart of the Excelsior/Shelley project proved to be a costly failure which never succeeded in making a successful flight.

With the Excelsior, the designers designed standard warp coils to fit the existing nacelles in order to allow the ship to travel at normal warp speeds. However, it was felt that the expense involved was too high for a mere cargo vessel, so the Shelley had its nacelles removed entirely and replaced with the units which were being taken off the Constitutions as they retired. Thus remodelled, the USS Shelley was launched and commissioned in 2287.

Although these ships would never reach the heights of flight performance which had originally been hoped for, as with their Excelsior cousins the Shelley still had an excellent space frame and basic systems, and proved to be a great success in service. The ships rapidly became a common sight and have continued in service ever since, toting an incredible variety of hardware around known space.

Since the advent of the Dominion war these ships have been used increasingly as amphibious assault vessels. The first batch of Excelsior's have long since retired, but many have had their engineering hulls removed and recycled as troop and/or ground vehicle carriers. The attachment point for these hulls is far aft of the normal point so as to allow a second hangar bay to be placed on the bow; the internal systems have largely been replaced by extra accommodation and vehicle storage. When in use with the Shelley class, the saucer section provides additional cargo and accommodation for the troops, allowing up to 6,000 to be carried and supported for over one month of full combat.

The Shelley itself is unarmed, and must be accompanied by protection if enemy vessels are nearby. So far several of these ships have been lost in the war, and more are expected now that the allies are on the offensive.