Unnamed Class J starships
List of unnamed Federation Class J starships.

Denevan ship

Starfleet training vessel 

In 2266, an old Class J starship was maintained by Starfleet for use as a cadet vessel for Academy trainees. 

During a training mission aboard this vessel, one of the ship's baffle plates ruptured and exposed the engine room to delta radiation. Fleet Captain Christopher Pike suffered severe radiation exposure and eventual paralysis due to his attempts to rescue the cadets who were trapped in the room. (; )

J