USN crew uniform colours during late 1800s?

This is some "deep water" to wading around in.  US Naval Uniform Regulations start gettign issued about 1810-1815, depending upon which source you wish to cite.  The copies of those regulations are often contradictory, and almost as often, under-informative.

The "navy blue" (black) used by the present crew of USS Constitution may not be "blue" enough, or it could be "just right."  The references often jsut site that the fabric for uniforms shall be of and "appropriate navy blue."  There are several publications that offer color plates of US Naval uniforms from the period; I've yet to see two that really match.  (That before finding two from the same printing to see if the ink used in the presses is anywhere similar for the whole run.)

Makes the life of a collector of things Naval slightly more complicated. it does.  (And I only collect back to 1939 <g> . . . )

As an interesting aside, the USN Officer's sword pattern was last established in the 1860 Regulations and has never been changed since (only the rules on who has to have one).  This will occaionaly cause some funny auction listings, like "Rare Civil War USN Sword" with a nice close up of a West German proof mark in the photos . . .

JTilley's advice mirrors my own.  Pick your best reference, and follow that.  A deep blue will probably appear more accurate than a flat black, except for officer uniforms, where a black base lightened with a scant bit of blue will likely serve best.  Hmbrol's Undoped Linen is good for Officer stockings, too (and helps break up the white-on-white-on-white).

I've never gotten deeply into the study of naval uniforms.  I do know that the basic answer to your question is:  very dark blue.  I think the basic enlisted man's uniform during the Civil War consisted of a dark blue jumper, a dark blue pair of pants, a white shirt, and a round, Royal navy-style cap with a ribbon.  I think a neckerchief, in the British style, also was part of the official uniform, but photos suggest that Union sailors frequently didn't bother wearing it.  The officers wore dark blue frock coats (with gold braid on the sleeves to indicate rank) and several different kinds of hat, depending on the occasion.  The old-fashioned "fore-and-aft hat" was still part of the USN formal dress uniform as late as the 1930s.  Under normal circumstances, though, officers wore hats that looked pretty much like the ones on the three officers in the Revell kit. 

I've got a couple of Civil War books that go into more detail than that; I'm heading out of town in a few minutes, but when I get back I'll take a look at them.

I do know (I think) the story on the figures in the Revell kits.  The Kearsarge and Alabama have the same figures that were originally sculpted for the Cutty Sark.  (And fine pieces of sculpture they are.)  The initial release of the Constitution contained a new set, with enlisted men in uniforms (some bareheaded and some in round, "tarpaulin" hats) and officers with swords and fore-and-aft hats.  One of the several Constitutions that I bought (I have no idea when) didn't have those figures in it; it had t he old Cutty Sark ones.  I think that was a temporary condition - maybe even an accident.  My understanding is that the Constitution kits sold in recent years have had the second, 1814-vintage figures.

The Revell figure sculptor went to work on that scale again in the mid-sixties to make the exquisite set of five guys for the 1/96 Golden Hind kit.  These are completely different from any of the others.  Many years ago I made the mistake of buying the big 1/96 "Spanish galleon" kit.  The overall awfulness of it in terms of realism is what I remember most, but I seem to recall that it did have a nice set of Elizabethan figures - some of them probably recycled from the Golden Hind.

Dr. Graham's book on the history of Revell includes an interesting anecdote about the figures that featured so prominently in early Revell kits.  Many of the masters for them were sculpted (usually at least five times the size of the finished product, to be reduced by an incredibly precise pantograph machine) by a gentleman named Tony Bulone.  By the late fifties Mr. Bulone was working free-lance, selling his work to other firms as well as Revell.  The Mattell Toy Corporation paid him $800 to sculpt the master for a plastic doll, for which he used his wife as inspiration.  That project, of course, turned into the Barbie Doll.  Dr. Graham doesn't say specifically that Mr. Bulone was responsible for the Cutty Sark/Thermopylae/Kearsarge/Alabama figures, but I suspect he was. 

The Constitution set looks to me like it was sculpted by someone else.  The figures are beautifully done, but their poses are a little stiffer and more formalized.