Command Strusture, Rank and Starship Mission DesignationPart I: Data
USS Enterprise, NCC-1701, crew 430
Commanding Officer: Captain
Executive Officer: Lieutenant Commander, later Commander [later Captain] (also Science Officer)
Second Officer: not specified - Lt. Cdr. Scott? Lt. Cdr. Gary Mitchell?
Chief Engineer: Lieutenant Commander, later Commander [later Captain]
Chief Medical Officer: Lieutenant Commander, later Commander
Conn Officer: Lieutenant, later Lieutenant Commander, later Commander [maybe even Captain!] (also Tac Officer)
Nav Officer: Ensign, later Lieutenant, later Lieutenant Commander, later Commander (also Tac Officer)
Comms Officer: Lieutanant, later Lieutanant Commander, later Commander
Tac Officer: not specified - Lt. Cdr. Giotto in Security?
Note: I included the later ranks in square brackets to sdet them apart, since the advancing age and seniority of the crew became increasingly unlikely, as indeed is the TNG crew now. . .
USS Enterprise, NCC-1701-D (& -E), crew 1014 (& ?)
Commanding Officer: Captain
Executive Officer: Commander [also a Captain, theoretically]
Second Officer: Lieutenant Commander (also Operations Officer)
Chief Engineer: Lieutenant, later Lieutenant Commander (other Lt. Cdr.'s also seen)
Chief Medical Officer: Commander
Ship's Counselor: Lieutenant Commander, later Commander
Helmsman: Ensigns, various Ensigns-of-the-week, Lieutenant J.G.'s, Lieutenants
Nav Officer: NONE (amalgamated with Conn)
Comms Officer: NONE (Riker/Troi internal comms, Worf external. . .)
Tac Officer: Lieutenants, one later Lieutanant Commander
USS Voyager, NCC-74656, crew c. 155 (now 135-140)
Commanding Officer: Captain
Executive Officer: Lieutenant Commander (as was the original, Cavit)
Second Officer: Lieutenant, later Lieutenant Commander (also Tac Officer)
Chief Engineer: Lieutenant (J.G.? Original not known)
Chief Medical Officer: Lieutenant Commander (originally; now no rank)
Ship's Counselor: NONE (made clear from start)
Helmsman: Lieutenant J.G., later Ensign (was Stadi a Lt. or J.G.?)
Ops Officer: Ensign
Note: I considered including the Defiant, but since it was added later and has a bizarre command structure that includes the Science Officer (the return of this term, and the assigning of Operations Officer to both the Chief Engineer - aka Chief of Operations - and even the Strategic Operations Officer!) as helmsman, and a Bridge crew that has included members of the Bajoran Defense Forces AND the Obsidian Order, Founders, and Ferengi Starfleet Cadets!
Part II: Discussion
1. Executive Officers:: The rank held here seems to largely depend on the size of the ship. Spock WAS initially a Lt. Cdr., but that might have been down to error by the costume department, since I don't think he was ever called that; at times, in "Where No Man Has Gone Before" it's almost implied that Gary Mitchell, of equal rank, is the exec. . . Two Miranda-class ships - the Reliant and the Saratoga had Lt. Cdr.'s as Execs, as does the Voyager. I think that whenever possible the Commanding Officer is always a Captain, while the Exec's rank depends on the size of the departments and the ranks of their Department Heads, all of whom report to him.
This is where I start to think that the science staff complement and their ranks gives a clear indication of what that ship's overall mission is. . .
2. Despite being seen now as overtly militaristic, I believe The Original Series depicted the mission of the Enterprise as being mainly peaceful exploration, albeit an expedition loaded for bear! No prominent Security Officer, Tactical duties shared between Conn & Nav, and the Second-in-Command is the Science Officer! Plus, they have a Comms Officer whose role it is to warn the crew of changes in alert status and receive reports from Departments, something that Riker would be seen doing in TNG (while Worf would handle external Comms).
3. In The Next Generation, the sheer amount of science being carried out makes the job of a Science Officer almost an absurdity. Instead the Exec, Ops Officer, Engineer and Cheif Doctor all assist in coordinating the ship's research, with the Captain, Tac Officer and Counselor lending a hand (yes, and there was The Boy. . .). Their continuing refusal to even consider that the ship's Head of Ops/Second Officer, plus the rise in rank of almost everyone else, makes the whole thing increasingly ridiculous, however.
4. On Voyager, the situation changes dramatically. VERY few scientific staff, the Ops Officer is a mere Ensign, while instead the Tactical Officer is a Lieutenant Commander (and given the early mixup over insignia, maybe should have been one from the start) AND the Second Officer. The Astrometrics Lab is in disuse until Seven of Nine comes along. Voyager is not a scientific ship.
Two more points I'd like to make:
5. As time goes on, I wonder more and more exactly how powerful the Sovereign-class starship is meant to be. Sure, we haven't seen families on board, but these days I doubt many Starfleet vessels take that risk. Plus, there is the assigning of a command crew with a clear scientific background, so much so that they complain bout the sheer amount of diplomatic work they undertake - and no-one wonders why they aren't in the thick of the Dominion War! Then there's First Contact: their surprise at not being included in the Typhon Sector fleet is as much their proximity to the marshalling point, and their experience in fighting the Borg, as in their belief that their ship is so powerful it makes a natural addition to the fleet.
Last one. . .
6. Many of the senior command staff, by which I mean Captains and Execs, have a certain background which has characterised their time in Starfleet prior to attainig high rank. Picard was a scientist initially (and might have stayed that way, as in "Tapestry") and always takes an interest in his ship's research; Riker was once in Operations (gold tunic in "Second Chances") and is often sent down to help in Engineering. Sisko's background is less clear, but after Wolf 359 he is sent first to a shipyards, then to a decrepit space station - is he an engineer? Lastly, Janeway, who we KNOW was a Science Officer, takes an according interest. . . yet, in times of crisis, she's more likely to go down to Engineering to help, leaving Chakotay (who seems to have been a rising star in Starfleet, probably with a pure Command background) on the Bridge. . . with more interest in science and engineering, how did she end up commanding a small warship?!
So, go figure. . . much of this we already knew, but I thought I'd take a fresh look at it. Just goes to show that TNG was actually quite well thought out, as was DS9, in terms of the characters. . . but Voyager wasn't! It's harder to spot any such themes in TOS, but I hope that what I've said will make those of you who don't rate Classic Trek give it another look.
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"I am greater than the stars for I know that they are up there and they do not know that I am down here." - William Temple