The USS Enterprise is so famous that its registry number gets reused several times for successor ships (NCC-1701-A, B, C, D, E, etc.).

Does this ever happen with any other Starfleet ships? Sisko's original USS Defiant (NX-74205) is replaced by another Defiant with a completely different registry number (NCC-75633), so apparently using letters to designate a replacement or successor ship is not a universal practice. Is the practice of using letters limited to the Enterprise, or are there other examples of this in any Federation era?

This question is not really asking when (that is, under what criteria) a letter is chosen for a replacement ship and when a full renumbering is given, but if the Enterprise was uniquely qualified in some way to receive a letter while all other replacement ships were not (because reasons), that's an answer.

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    One possible explanation about the Defiant 2 not having a matching registry number is that it was originally the USS Sao Paulo. It was renamed to Defiant under a special dispensation, but that might not include a registry update.
    – Servitor
    Commented Jun 19, 2018 at 16:17
  • 4
    @Ben though the standard understanding is that the Enterprise-A was originally the USS Yorktown and renamed due to Kirk and company's bravery. Why would that one include a registry update and the other not? Was Sisko less brave than Kirk? Certainly, he got laid less often, but that's not the same thing. Commented Jun 19, 2018 at 16:22
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    Do you have a good source for the Yorktown rename to Enterprise? I see on memory alpha that non-canon sources have claimed it but nothing official. memory-alpha.wikia.com/wiki/USS_Enterprise_%28NCC-1701-A%29 I would think the registry number is mostly used as a unique ID, I don't see why they would change it as a reward.
    – Servitor
    Commented Jun 19, 2018 at 16:31
  • @RobertColumbia, it is with all those weird aliens with weird anatomies and weird diseases. Commented Jun 19, 2018 at 16:52
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    Tangent - I see to recall that the prefix "NX" was for prototype or experimental ships. Am I hallucinating? Commented Jun 19, 2018 at 17:55

4 Answers 4


Main Canon

Two ships in the main canon have suffix designations:

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RIKER: It's a Federation ship. NCC one three zero five dash E. It's the Yamato, our sister ship.

EU Canon

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    Interesting note on the Yamato: According to Star Trek Encyclopedia (4th ed., vol. 2, p.505), the initial NCC-1305-E registry number was a production mistake. It was given to the Yamato by the episode writer Jack B. Sowards who was unaware of the registry numbering scheme developed for Star Trek: The Next Generation. Michael Okuda had intended to correct the number
    – Machavity
    Commented Jun 19, 2018 at 20:21

In the TNG episode "Where Silence Has Lease" the Galaxy class Enterprise NCC-1701-D encountered what seemed to be a sister ship the Galaxy class Yamato NCC-1305-E, but it turned out to be a fake ship created by the strange alien being Nagilum.

WORF: Captain, there's another vessel approaching in sector zero nine one, mark two six.

PICARD: On screen. Magnify.

RIKER: It's a Federation ship. NCC one three zero five dash E. It's the Yamato, our sister ship.

Where Silence Has Lease

In the TNG episode "The Measure of a Man" an Okudagram said, that the Galaxy class Yamato NCC-24383, commanded by Captain Richard Mackenzie was patrolling the Neutral Zone in sector 134.

The Measure of a Man, Okudagram  image

In the TNG episode "Contagion" the Galaxy class Enterprise NCC-1701-D encountered the real Galaxy class Yamato NCC-71807 under the command of Captain Donald Varley.

A piece of hull from the exploding Yamato has 71806, but dialog in the episode establishes that the registry number is NCC-71807.

Thus we see that the USS Yamato also had a registry number with a letter suffix. Why did the Yamato also have other registry numbers? Maybe in the era of TNG some starships have two or more registry numbers at the same time, or maybe Starfleet kept changing the registry number of the Yamato for some reason.

In real life, this was the result of various errors and failures to communicate by the production staff of TNG. But in the universe of Star Trek each of the Yamato's registry numbers is correct and valid.

In the era when TNG was produced, physical models of starships would keep their hull markings as long as they lasted, or until someone physically repainted them. And computer graphic models of starships would also keep their hull markings until somebody reprogrammed them to show different hull markings. So a specific starship would have the same registry model on its hull every time it was shown.

But how do we account for the different registry numbers of the Yamato in the fictional universe of Star Trek, since each number is as canonical and correct as the others?

With the technology of almost 400 years in the future, it is easy to believe that it would be trivaly easy to program different parts of a starship hull to show different colors and thus to rewrite its registry numbers. Thus if Starfleet kept changing the registry number of the Yamato the hull would keep changing its pattern to show the new registry number. And if the Yamato had several different registry numbers at the same time the ship could be programmed to cycle between numbers on the hull, switching at regular intervals.

And since the ship could be programmed to display different registry numbers on the hull, the Iconian invasive program that was interfering with the ship's computer programming could have cause the number on the hull to change from 71807 to the inaccurate 71806 before the Yamato exploded.

And maybe the Enterprise also has two or more registry numbers, and its hull markings may display each on in turn in a regular cycle, but we only get to see one of those registry numbers, NCC-1701-D.

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    This appears to be a very extended comment on my answer above rather than an answer in its own right
    – Valorum
    Commented Jun 19, 2018 at 18:53

The technical manuals are many and varied - I could post walls of text drowning in details - here is the SPECIFIC reference to the Yamato A; there are many, many others - if one cares to 'dig them out' from the voluminous reference works. These ARE canon, used by filmmakers, writers and game makers. Star Trek Online is a prime example of meticulous attention to detail. Examine the 'guidelines' for any attempt to have a star trek novel published and you run up against the Canon regulations - from the technical manuals.

USS Constellation-NCC 1017** USS Yamato - NCC 1305-A 
USS ENTERPRISE - NCC 1701 USS Nimitz - NCC 1702 USS HOOD - NCC 1703 USS BISMARK - NCC 1704 USS Excalibur - NCC 1705 USS Exeter - NCC 1706 
USS Valiant - NCC 1707** 
USS intrepid - NCC 1708** 
USS Lexington - NCC 1709 
USS Kongo - NCC 1710 USS Potemkin - NCC 1711
 USS Bon. RichARD-NCC 1712 USS Monitor - NCC 1713
 USS HORNET - NCC 1714 USS Merrimac - NCC 1715 
USS Endeavor - NCC 1716 USS YORKTOWN - NCC 1717 USS ESSEX -
 NCC 1718 USS Akagi - NCC 1719 USS Ti-Ho - NCC 1760 USS Soryu - NCC 1761 USS Hiryu - NCC 1762 USS Endeavour - NCC 1763 
USS Defiant - NCC 1764**
  • So... none of these have a letter next to them, except the Yamato (which was mentioned previously). Also, you don't cite where this came from
    – Machavity
    Commented Jun 27, 2018 at 0:10

The limitation to answering this seems to be excluding books.
There was a "Yamato A" in book form. In the actual medium of film/TV it was not used as I recall.

In the star trek technical manuals(which are deemed canon) there are numerous and varied ship designations dependent on form & function. A designation of any ship ending with an X to indicate an experimental ship.

Legacy ships designated by alphabet - currently the enterprise is, in variants, as far along as J.

The crash of the D where Riker mourns his loss of chance to 'sit in the captains chair' and Picard confidently replies that this won't be the last ship named "Enterprise'.

Historical canon demands legacy ships - recall the loss of the Excalibur in the M-5 experiment. The Loss of the Intrepid(an entirely Vulcan crew) in the giant space cell episode.....

the list goes on.

  • 1
    This would be a better answer if it had references. Which book does the Yamato-A appear in? Is said book considered canon?
    – F1Krazy
    Commented Jun 24, 2018 at 17:22
  • @F1Krazy - None of the fiction novels are canon
    – Valorum
    Commented Jun 26, 2018 at 11:32
  • no but the technical manual are and they provide multiple ship type classes and designations.
    – Alan
    Commented Jun 26, 2018 at 11:34
  • @Alan - Brilliant. Can you give some specific examples and which books they appear in?
    – Valorum
    Commented Jun 26, 2018 at 12:51
  • engineering.thetafleet.net/Journals/TOS/…
    – Alan
    Commented Jun 26, 2018 at 23:50

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