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J Class

Size Comp
Universe : Prime Timeline
Affiliation : Humans
Class Name : J Class
Type : Cargo Ship [1]
Unit Run :
ECS Constellation [2] - Retired
ECS Horizon [3] - Retired
plus 13 others built in total. 4 have been lost in all. 11 have been retired from service.
Commissioned : 2095 - 2105, remained in service until 2205
Dimensions : Length : 339 m
Beam : 140 m
Height : 59 m
Decks : 8
Mass : 855,000 metric tons
Crew : 15
Armament : 2 x plasma cannon [1] , total output 2 TeraWatts
Defence Systems : Light Monotanium Single hull plus 0.2 cm Polarised armour. [1]
Low level Structural Integrity Field
Warp Speeds
(TOS scale) :
Normal Cruise : 1.5
Maximum Cruise : 1.85 [1]
Maximum Rated : 2 [1] for 1 hours.
Strength Indices :
(Galaxy class = 1,000)
Beam Firepower : 0.04
Torpedo Firepower : -
Weapon Range and Accuracy : 2
Shield Strength : -
Hull Armour : 5.31
Speed : 4
Combat Manoeuvrability : 440
Overall Strength Index : 8
Diplomatic Capability : 2
Expected Hull Life : 100
Refit Cycle : Minor : 5 year
Standard : 5 years
Major : 50 years


The J Class cargo ships were an early Human craft whose engines were designed by Zefram Cochrane himself - in fact rumour has it that the great man signed the inside of each reactor casing. [2] Like all Human ships of the early 22nd century, the ships were limited to speeds just above Warp 1 [3] - though later in their life they benefitted from refits which raised this to warp 2 or more. [2] Interstellar voyages still took years or even decades, and like all Human cargo ships of the time these vessels were largely crewed by families. They were small, agile craft when not towing cargo, and with their two plasma cannon they were quite well armed for their size. [2]

In an alternate timeline, at least one J class ship was part of the fleet which took the remnants of Humanity to Ceti Alpha V after the Earth was destroyed. [4]

Colour key

Canon source Backstage source Novel source DITL speculation


# Series Season Source Comment
1 Generic canonical information
2 ENT 2 Horizon
3 ENT 1 Broken Bow
4 ENT 3 Twilight
Source : Generic canonical information
Series : ENT Season 2 (Disc 5)
Episode : Horizon
Series : ENT Season 1 (Disc 1)
Episode : Broken Bow
Series : ENT Season 3 (Disc 2)
Episode : Twilight


The long-awaited J Class cargo ship was first seen in Enterprise's "Horizon", where the ship of the same name was a J class. Mayweather had mentioned the class the previous year as being an ancestor to the Y class seen in that episode.

The Horizon was carrying various cargos, including 30,000 tons of ore. Dumping some of this allowed the ship to increase its top speed from Warp 1.85 to Warp 2; since not all the ore is dumped, presumably the ship could get slightly above warp 2 with no cargo at all. This is actually pretty fast for a Human ship, especially one as old as the J class - which is said to be fifty years old in the episode. Perhaps some of the high warp technology developed for Enterprise is beginning to make its way onto civilian ships?

The Horizon is fitted with two plasma cannon, and performs very impressively in battle with the pirate vessel in the episode. Mayweather has upgraded the cannon, but this has only increased their firepower by 80% - yet they comfortably defeat a vessel many times their size.

© Graham & Ian Kennedy Page views : 47,344 Last updated : 4 Apr 2013