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Romulan D7 Class

Size Comp

Klingon import, figures for 2265

Universe : Prime Timeline
Affiliation : Romulans
Class Name : Romulan D7 Class
Type : Cruiser (Obsolete)
Unit Run : Total 437 imported since 2245. 112 were in service at the beginning of the Dominion war; 60 of these were lost in the war. 437 built in total. 102 have been lost in all. 335 have been retired from service.
Commissioned : Dates uncertain, but in service as of 2267 [1]
Dimensions : Length : 228 m [2]
Beam : 160 m [3]
Height : 60 m [3]
Decks : 18
Mass : 344,000 metric tons
Crew : 480
Armament : 10 x Mark 7 disruptor cannon [4], total output 5,500 TeraWatts
2 x Basic photon torpedo tube with 260 rounds
Defence Systems : Standard shield system, total capacity 81,000 TeraJoules
Heavy Monotanium Double hull plus 5 cm High density armour.
Standard level Structural Integrity Field
Warp Speeds
(TOS scale) :
Normal Cruise : 5
Maximum Cruise : 6
Maximum Rated : 8 for 10 hours.
Strength Indices :
(Galaxy class = 1,000)
Beam Firepower : 110
Torpedo Firepower : 100
Weapon Range and Accuracy : 40
Shield Strength : 30
Hull Armour : 520
Speed : 267
Combat Manoeuvrability : 6,000
Overall Strength Index : 139
Diplomatic Capability : None
Expected Hull Life : 100
Refit Cycle : Minor : 5 year
Standard : 5 years
Major : 20 years


In 2268 Starfleet Intelligence reported a most troubling development - the Romulan Empire had acquired a substantial number of Klingon D-7 class battle cruisers to supplement their fleet. [1] Somewhat ironically, the impetus for this move on their part could well be the actions of the Federation Starship Enterprise. The Romulans had fielded a new "bird of prey" type vessel in 2266. As a test of this ship one was sent across the Neutral Zone to attack the Earth outposts along the border. The Enterprise engaged the Romulan ship in battle, ultimately defeating it. The loss of their most advanced vessel must have demonstrated to the Romulans that they had little chance of mounting a full scale invasion of the Federation; more worryingly, it may have implied that their own borders were not safe from possible Federation incursions. [5]

The precise nature of the deal the Romulans struck with the Klingons is unknown even today, but intelligence agnecies have speculated that the Romulans traded their cloaking technology for Klingon warships. In the hands of the Klingons the D-7 was considered to be somewhat less than a match for the Constitution class, one-on-one. But when fitted with a Romulan cloaking device the Klingon vessel had a huge advantage over its Federation counterpart.

Fearing a Romulan invasion, the Federation felt it had no choice but to act. Captain Kirk was sent on a mission into Romulan space, feigning mental unbalance in order to give the Federation a degree of deniability. His ship was quickly surrounded by D-7s, and Kirk was able to infiltrate the lead ship and steal its cloaking device. The Romulan commander was also captured as the Enterprise made its escape. [1]

By treaty the Federation is not allowed to develop or deploy cloaking technology, a rule Kirk briefly broke by using the captured Romulan device to evade persuit and return to Federation space. [6] Posession of the cloak allowed Federation scientists to devise counters to it, mostly in the form of more advanced sensor systems which were able to partially negate the cloak's invisibility.

Despite their posession of the D-7, the Romulans never did mount a serious invasion of the Federation. [7] Little is known about the service life of the D-7 in Romulan hands, but by 2344 the Romulan fleet was equipped with Warbird type vessels which took part in the attack on the Klingon outpost of Narendra III. [8] It is probable that the Romulans retired their D-7s as relations with the Klingon Empire went sour, so as not to have to rely on them for spares and support. A date of 2325 is generally regarded as being a reasonable figure for their retirement.

Colour key

Canon source Backstage source Novel source DITL speculation


# Series Season Source Comment
1 TOS 3 The Enterprise Incident
2 Star Trek Deep Space Nine Technical Manual Calculated from the scale diagram on page 317, assuming it is the same size as Klingon D7
3 Star Trek Deep Space Nine Technical Manual
4 Generic canonical information
5 TOS 1 Balance of Terror
6 TNG 7 The Pegasus
7 Various Original Series episodes
8 TNG 3 Yesterday's Enterprise
Series : TOS Season 3
Episode : The Enterprise Incident
Book : Star Trek Deep Space Nine Technical Manual
Comment : Calculated from the scale diagram on page 317, assuming it is the same size as Klingon D7
Book : Star Trek Deep Space Nine Technical Manual
Source : Generic canonical information
Series : TOS Season 1
Episode : Balance of Terror
Series : TNG Season 7
Episode : The Pegasus
Series : TOS Season
Episode : Various Original Series episodes
Series : TNG Season 3
Episode : Yesterday's Enterprise


The D7 was seen in Romulan hands in the TOS episode "The Enterprise Incident". A long-standing rumour has it that their acquisition of these ships came about when the Romulan bird of prey model was dropped, resulting in damage that prevented it being used in the episode! We know nothing canonical beyond what we saw in "The Enterprise Incident", but some novels have suggested that the ships the Klingons gave to the Romulans were not exactly in the best of condition or up to their full specs. Nevertheless, I have given the ship the same specification as the Klingon D-7. For more details of the D-7s history and variants of this design, see my article on the Klingon Battlecruiser.
© Graham & Ian Kennedy Page views : 61,413 Last updated : 22 Dec 2021