Here was another attempt at a Decker redraw http://www.tacticalstarshipcombat.com/FASA/sds/Ship Images/decker_Destroyer.jpg
I dare say it was convincingly described as one, given how the hero ship couldn't even afford to carry spares. But we also saw several "insignificant" or "frivolous" ships such as pleasure cruisers; supposedly, those would not be running on dilithium, or else only quadrillionaires rather than the likes of Leo Walsh or Cyrano Jones could operate them. If certain ships can make do without dilithium, Starfleet might actually invest heavily on those. Timo Saloniemi
Perhaps ships with lower maximum warp factors could operate without dilithium. But that would result in more slow freighters like the early to mid 22nd century and effectively a bunch of planetary defense forces that can't do better than say Warp 5, if that. (Simple impulse power? Fusion drives?) The rapid response forces and the deep space exploration vessels would be the ships that can make high warp speed with the dilithium installed.
FASA's oddball Samson class tender is perhaps an example of a design that's too specialized in terms of its actual mission - towing the big Regula type starbases around if they need to change locations.
This was pretty much what I was thinking, although, I suppose small ships could also utilize much smaller crystals, which would be more common.
I'm actually fond of the idea that Kirk's ship usually operates on microscopic dilithium, embedded in those ping-pong paddle things seen in "The Alternative Factor" - the equivalent of industrial diamonds today. This dilithium dust matrix easily goes out of alignment and needs to be re-energized in a dedicated machine, but it's the best Starfleet can do as naturally occurring large crystals are extremely rare and expensive. Perhaps the microscopic dilithium dust is what one gets when a large lump decrystallizes, and only by the time of TNG do they learn the trick of turning a degraded lump back into a workable one (as we certainly see lumps and shards being used in TNG "Skin of Evil" et al.). NX-01 already used dilithium the way it is used in TNG, to focus and regulate an annihilation reaction, as per fourth season dialogue. But we didn't learn whether they used macroscopic or microscopic crystals, so there could be steady progress there, rather than an odd sequence of TNG style - TOS style - back to TNG style. Then there's the VOY fact that a substance called paralithium will do, even though it performs poorly. Perhaps "lithium crystals" is a catchall name for paralithium, dilithium, tri-translithium and whatnot, and Kirk's ship prefers the high-octane dilithium but might be a flexifuel (or flexifocus) machine capable of operating on other types of lithium-containing crystal as well? Timo Saloniemi
I'm not sure if this would exactly fit the category of a ship, but Battletech has another interesting entry in the form of the Space Defense System (SDS). The original version was an advanced, largely autonomous network of modified ships of various types with a robotic control system, designed to be controllable by a relatively small number of human operators. The most infamous were the M-5 capital warship drones, based on the Lola destroyers with the weapons package upgraded to nearly that of the Texas class battleship, one of the SLDF's primary heavy guns. The space borne elements could also be supported by specialized ground units whose fire could reach orbital levels. This version also had an advanced sort of AI which served as a repository for the knowledge and experience of many commanding officers, which meant the autonomous drones were familiar with SLDF tactics and often capable of adapting to the most dangerous enemies. The system wasn't perfect, though, as all versions of the drones suffered from some degree of electromagnetic vulnerability which could disrupt their ability to coordinate attacks. It was also impossible to reliably have drones transport to other systems FTL, as this would disrupt their computer systems. They would be shut down and transported under human direction over such distances. Most of the original SDS was destroyed during the Amaris Civil War, with the surviving elements destroyed by the SLDF. The Word of Blake later revived a version during the Jihad and came the closest to recreating it, but lacked the ability to reproduce elements like the tactical database.
I have imagined old ships in a sort of tramp steamer role. Perhaps there are old ships comparable to Serenitiy.
Apparently, with specialized but modular mission pods, a (nonspecialized) utility vehicle may be practical. That is, the specialization is in the pod, while the the basics, such as energy, propulsion, crew quarters, etc. is in a generic chassis. The Nebula class seems to be a large sized example The New Orleans class seems to be a small pod/utility vehicle. On the other hand, for small ships a lack of room (and small size of pods) might result in a tendency for specialization. In a few cases a design might straddle categories. As a middling size ship, Voyage might be classified as a Smaller Explorer/Large Scout.
The smaller ships might have swappable internal components to change there specialization. Sort of like the Runabouts have internal sections that can be changed out, a smaller starship might also have a pallet of rooms that can be switched out at a starbase.
One has to wonder how specialized Starfleet designs are. They seem like more often they are multi-mission ships selected for a specific mission set. Miranda-class ships have been seen doing just about every task from one ship to another. Sometimes they send smaller ships to do things instead of larger ships, but sometimes I wonder if all these designs are redundant due to the multi-purpose nature of most starships. Especially by the time they start getting the First Contact ships involved during the Dominion War. By that point Starfleet is using lots of: Miranda, Saber, Akira, Steamrunner, Excelsior, and Galaxy-class ships with an mix of various weirder mostly background designs, plus some Centaur and Defiant-class ships and fighters. This is without as many Constellation, Norway, Nebula, Intrepid, Oberth, and certainly without the Sovereign-class showing up. Almost all of those ships are multi-purpose ships aside from the Oberth, which is almost always a science vessel. So what specialization/classification is Starfleet using for all these starships classes?
Going by sources like FASA and Jackill's, there's more of a direct naval analogue with ships being more or less specialized depending on their role in the fleet. Destroyers are fast vessels with moderate armament for their size, frigates are heavier and can support tactical operations by their firepower and troops, and cruisers tend to be jack of all trades. It could be that by the TNG era, Starfleet was using more flexible designs than a larger number of mission specific ones.
It might also be that in TNG peacetime, we mostly saw ships that were operating in the same distant areas as the hero ship, therefore doing similar things - but dedicated ships would have existed elsewhere. In wartime, OTOH, everything that could fly through space and fire a phaser could and should be included in a fleet, as per "pre-dreadnought" naval doctrine: the side with more guns automatically wins, and even short-ranged peashooters add to the vital total. Timo Saloniemi
One thing I've had in mind ever since those hugh blimp-y looking things in the sky in ID is, could Starfleet (or a civilian agency) have and operate never before seen class(es) of ships for Tourism among Federation Worlds - Warp Capable Cruise Ships! Surely the massive civilization depicted in NuTrek, and by extension, an assumption civilization exists on that scale and beyond throughout the Federation, would have need to travel between worlds for reasons of both pleasure and business. So would old, recycled starships of Starfleet be adequate enough to meet this potentially humongous need to move civilians around off worlds, or could/would something separate and specific to the task be required? As you can see a whole new world of opportunity in ship function and design opens up. But, yeah, technically, it's not canon. Just an idea I've been mulling over. This looked like a good place to share. Please feel free to run wild with, or ignore, as you wish.
We have often seen passengers travel on what look like military transports (the Sydney class vessels in DS9), but this need not mean there wouldn't be other types of liner, as well as cruise ships and the like. Then again, it can mean exactly that - perhaps Starfleet really controls everything relating to starflight? Yet it is curious that we never get a dialogue mention of space tourism. Civilians traveling on liners or military transports always seem to be on serious business. Or then they travel to a specific resort, usually Risa, which is not quite the same as booking a cruise. Really, the closest thing to cruise vacations is the Boomer lifestyle from ENT, with all the stories about strange alien ports. But it's not quite vacation, either, even if one might theoretically consider some of the family members "passengers" rather than "crew". As for noncanon ideas, the old Spaceflight Chronology already had a cruise ship included. The Stellarford (nod to the illustrator?) is called a "starliner", but described as carrying "tourists" to "excursions" to "galactic wonders", rather than running a line in the traditional sense. Timo Saloniemi
I'm beginning to think of a distinct category-Old Beater sips. Ships of 23rd century design in the late 24th century. The Miranda class might be another category-positively ancient Old Beater.
Sure, Jackill's third volume includes such a design specifically (the Rising Star class liner), and the Sydney might also fall under the same classification. I think FASA might have had one or two civilian designs like this as well, but I could be remembering wrong.
FASA had the Cosmos Royale liner from their 'A Doomsday Like Any Other' supplement. For a long time the Ring ship Enterprise was considered the first interstellar liner that went to Alpha Centauri just prior to the invention of the warp drive.