The V's'talo-class (known in translation from Klingonaase, literally, as the Watcher-class, alphanumeric designation K5-class) was a Klingon class II (for the K5B) or class III (K5C) gunboat starship in Imperial Defense Force service in the 23rd century, becoming active sometime before 2207 SFC.
- In the Spaceflight Chronology dating, 2207 SFC is a few years before the events of Star Trek: The Original Series, and so would roughly correspond to the early 2260s in the standard timeline.
The K5 was created in the mid-23rd century and crewed 18 officers and men, with accommodations for 6 passengers. Additionally, the K5A could carry 750 metric tons of cargo, rated at 15 SCU (standard cargo units). Unloaded, the vessel weighed 12,950 metric tons, measured 94 meters in length, 38 meters in width and 18 meters in height. The K5C modification had a different internal structure and had dimensions increased to 96 meters in length and 20 meters in height, and a near doubling of the ships mass to 23,300 metric tons.
The K5 warp engines were KWB-2 type, rated to cruise at warp six and max out at warp factor 7. The weight change of the K5C modification affected the engine performance, limiting those heavier vessels to cruise at warp 5 and max out at warp 6. K5B Impulse engines were of the KIA-2 type, while the K5C was uprated to KIB-1 engines. The K5B had 2 KD-3 disruptor emitters, with a single forward fire arc, while the K5C was uprated to two KD-12 disruptors, expanding arcs of fire to fore as well as port and starboard. The vessel a no launcher weapons and was defended by KSE (K5B) or KSD (K5C) model deflector shields depending on the subclass.
By the later 23rd century, the K5A was still in production, with 40 vessels per year being built at Iosia, Fonawl and Z'hai. The K5B modification entered service sometime between reference stardates 2/0711 and 2/1803, with over 403 vessels built. Of those, 5 were later captured by Starfleet, 29 went missing, 12 traded outside of the Empire and 22 given to private service. The K5C modification entered service on reference stardate 2/1404, with over 652 vessels built by the 2280s. In total, as a class, the K5 consisted of over 765 vessels built, 577 remaining in service by the late 23rd century, 8 assigned to training duty and 106 destroyed. (FASA RPG module: Klingon Ship Recognition Manual)