The Naming Of Ships Is A Difficult Matter

Originally published at: The Naming Of Ships Is A Difficult Matter | The Associated Worlds

pennant number: The Imperial Navy’s best attempt at a general purpose identification code for ships, other means having proven inadequate.

It is generally held that the true identifier of a ship is its name: that is, after all, what is written upon the hull, and with it travels the ship’s crest and other naval heraldry, figurehead, relics, and traditions. More importantly, the name itself travels with the spirit of the ship.

While this is definitive from the perspective of aelvaqor, this is unfortunately inadequate for administrative purposes. Eucharion’s Spear, for example, has in its time been a war galley (w/RG-14¹), two first-rate ships of the line (w/RL1-12 and w/RL1-56), two battleships (w/BB-4 and w/BB-82), a submarine battleship (w/BS-156), two star battleships (BB-6 and BB-183), and three star dreadnoughts (BD-47, BD-200, and BD-486).

A second form of identification is the hull number, assigned to the hull upon construction. Hull numbers consist of an alphanumeric designation for the graving dock in which the hull was constructed, followed by the serial number assigned by the dockmaster to that hull.

This, too, is inadequate for administrative purposes as it relates to the ship entire. Over the course of its life, a single hull may undergo several refits, which may alter many of the ship’s characteristics, even to the point of altering its type. Consider, for example, the case of Damaschira, who began her career as a Simélia-class destroyer (w/DD-1161), was later retyped along with the rest of her class as a destroyer escort (w/DE-2217), and finally was refit as a dedicated minesweeper (w/MS-141).

For this purpose, the pennant number² was devised. Assigned to a given ship (hull) when it is commissioned, along with its name, the pennant number is updated whenever the ship undergoes a significant refit³ and is never reused after the ship is eventually scrapped and passes its spirit and name to an heir, thus providing a unique designation for both the individual ship and its current set of capabilities and characteristics.

The pennant number consists of a type prefix (also known as the flag superior), identifying the type of the vessel, followed by a numerical suffix (the flag inferior), indicating the order in which the ship in question was commissioned as that type. A ship which is refit into a new type and then back into its original type acquires a new pennant number, unless the second refit is merely to restore its original class.

Small craft are not issued names or pennant numbers, and instead – for administrative purposes – use the pennant number of their mother ship with a numerical suffix indicating order of assignment. For communications, a flight number is used instead.

Blackjacket’s Dictionary


  1. Historically, not all ships were assigned pennant numbers at the time of commission. Type codes beginning with “R” indicate pennant numbers assigned retrospectively to ships of types which no longer exist. Similarly, both the wet navy and space navy use similar pennant number systems; where both are used in the same context, it is conventional to prefix wet navy pennant numbers with “w/”.
  2. Originally flown by wet navy ships by means of signal flags, hence the name and the names of its components. In later years, and by space navy ships, the pennant number is signaled by the ship’s transponder and used in tactical mesh packet headers.
  3. The definition of significant refit is somewhat ambiguous, but is traditionally held to include any refit sufficient to change the type, or even class, of the ship in question.

I think the way I’d do it, as CNO of the Dzibanian Navy, is have a single, sequential series of hull numbers shared by all ships, along with a classification code. The hull number would never change even if wildly refit, just the classification code would change. CA-303 might have her guns removed and her deck razed to become CVL-303, or whatever. The name, like the hull number, would never change (it’s terrible luck, anyway).

Not grokking well the difference between the pennant and hull numbers.

The former identifies the ship as a functional unit; the latter identifies a physical hull.

So, to give a worked example example, the Navy orders a new cruiser from Ethring Iron and Steam Works, which they build in their #3 graving dock. When work begins, the physical hull under construction is assigned the hull number ESW03-01307, indicating the place of manufacture and that it’s the 1,307th hull constructed in that dock.

When commissioned into service, the Navy assigns her the name CS Intransigent, taken from the naming list for cruisers, a name which - along with some of the steel used in her construction and relics to be used in her fitting-out - she inherited from a previous Intransigent, since decommissioned. The Navy also assigns her a pennant number, CC-303, identifying her as a cruiser and the 303rd commissioned into the fleet.

Some years later, the situation has changed and the Navy needs a light carrier more than an aging cruiser. Intransigent is selected for this refit, and she goes for refit at Sukórya Graving & Drydocks, where they remove her turrets, plate her over, and so forth. When she’s recommissioned after her refit, she keeps her name, and also keeps her hull number; it’s still the same physical hull, which will be ESW03-01307 until it’s finally scrapped. However, she’s no longer the same functional unit, because a light carrier obviously has a very different function to a cruiser. In recognition of this, she’s issued a new pennant number, CVL-117.

Some years more later, they may refit her again, say, to a missile-armed cruiser. In that case, she needs a pennant number identifying her as a cruiser, so she reclaims her old number, CC-303. If she was instead refit as, oh, a destroyer leader or a submarine tender, she’d have changed types again, and would so get a third pennant number for her new career in her new (functional) type, but would continue to bear the same name and hull number.

When she is eventually scrapped, her name, relics, and steel will be passed on to the next Intransigent, but neither the hull number ESW03-01307 nor any of her pennant numbers will be reused.

Did that clarify things any?

It sure did. My mistake was in associating the eldraic hull number with the literal term used in the US Navy, when that is functionally cognate to the eldraic pennant number. The term hull number is here being used as it is applied in our civilian shipbuilding, and indeed as it is applied in our civilian ground transport manufacturing as well.

Since I was reading the OP examples as hull numbers, I was naturally confused when you seemed to both endorse and deprecate them at the same time.

Would it not be logical to assign a supernumerary suffix at each refit, even if only in Naval internal logs? – e.g.

ESW03-01307-1.0 CS Intransigent (CC-303)
ESW03-01307-2.0 CS Intransigent (CVL-117)
ESW03-01307-3.0 CS Intransigent (CC-303, refit)

… because even the union of {hull # | pennant #} is not a sufficiently specific lookup key to retrieve a single set of blueprints from the Yards database, and that seems like a pretty basic requirement.

Minor upgrades and repairs would, naturally, get intermediate version suffix tags, though probably only stored as diffs. Ideally, the system should be able to take a request like “Show me the complete logged blueprint of CS Intransigent at 04:47+ on such-and-such date”; retrieve from the log the exact version number extant (say, 2.05.23948, during his carrier days), extract the 2.0 blueprints as logged at Sukorya, apply all patches to the blueprints as spec’d in the diffs, and return precisely what the Navy understood CS Intransigent’s “full and proper kit” to be at that moment.

Which is necessarily a different thing from the physical reality of that moment, since no ship ever perfectly matches blueprints no matter how well documented, plus battle damage, wear and tear, unreported fermentation experiments, and whatnot. But intentions matter, and no one knows that better than eldrae.

All in the ship’s papers, it is.

(And in the copy of the ship’s papers backed up at the registry, but the ship’s papers aboard are definitive. That’s because of ubiquitous computing, and WeaveControl™, and thus the way that everything from massive spar assemblies to single rivets comes v-tagged and networked such that the ship herself can complain mightily when the actuality doesn’t match the design plat.

A product courtesy of generations of engineers who get very cranky when the system doesn’t match what the system claims to be.)

These electronic machine-readable documents come in very handy for yard dogs in distant ports (who might not mind waiting while couriers schlep the necessary out to them, but who would also certainly bill you for their time), space traffic control, damcon bots, etc., etc.

And, of course, they’re fully version controlled and stored in the 'verse’s equivalent of git, so if you want to ask questions like that, you can go from the pennant number to the hull number to the corresponding set of papers, and then armed with a date and time you can pull the exact spec as of then, or at least as of then modulo the last registry sync. (Also, since it includes branches and tags and so forth, which bits are officially blessed upgrades, which are actual refits, which are engineers being clever, which were done in which yards, which upgrades/refits/clever ideas were considered but never actually implemented, and so on and so forth.

(Also, as per

Distinctions | The Associated Worlds (

even the, cough, fermentation experiments are on the plans if they’re hardwired. The Chief Engineer is careful not to know, the bosun knows unofficially - being possessed of hullwise omniscience - but the ship absolutely knows.

(Although it’s not like the IN is dry anyway, so there are probably better options on offer than rocket juice.)