There are lots of good sources for ship plans. The two Mr. Stauffer mentioned are/were dealers; they carry/carried vast numbers of plans from different sources. I think Mr. Stauffer's right: The Dromedary is out of business. Taubman's carries literally thousands of plans drawn by hundreds of different draftsmen. Some of the plans from that source are among the best in the world; others are awful, and many, many rank somewhere between.
Woodwizerd's blanket condemnation of plans included in kits is too harsh. It sounds like he's had a bad experience with a kit from Corel - and that company's plans are indeed pretty awful. Corel is one of the notorious HECEPOB (Hideously Expensive Continental European Plank-On-Bulkhead) manufacturers, who usually don't have the slightest interest in making their kits accurate. But there are kit manufacturers who supply excellent plans. One thing to remember, though: all model kit manufacturers evolve. It's not safe to assume that if one set of plans from a manufacturer are good, all that manufacturer's plans are.
Two good American sources are Model Shipways (sold by Model Expo: www.modelexpo-online.com ) and Bluejacket ( www.bluejacketinc.com ). You won't find a better set of plans for a Gloucester fishing schooner than Eric Ronnberg's drawings for the Model Shipways Elsie and Benjamin W. Latham, and the Bluejacket plans for the U.S.S. Constitution are pretty widely regarded as the most accurate available. Be warned, though: both those companies have been around for a long, long time. If you buy plans from them sight-unseen, you may get something that was drawn back in the thirties or forties and doesn't approach modern standards.
My personal favorite line of plans drawn specifically for modelers is, I think, the ones drawn back in the sixties and seventies by William Crothers under the label Seagull Models. They're sold by Taubman's. Unfortunately the range is small; the ones I remember off the top of my head are the clipper ships Challenge, Comet, and Young America, and the American sailing warships Germantown and Pennsylvania. I'm sure there were a few others - but not a lot. If you're interested in a latter-day European merchant ship, you should look into the work of Harold Underhill. (Taubmann's also carries his drawings - but at hideously high prices. I'm sure there's a cheaper source.)
Don't overlook the possibilities of plans in books. There's a series of books, published by the Conway Maritime Press, called the "Anatomy of the Ship" series. They do vary somewhat in accuracy and detail, but they're generally superb - and each includes hundreds of drawings covering almost every detail of the ship in question. The Longridge book that GMorrison referred to is superb; it used to come with a full set of plans for the Victory folded up in a pocket inside the back cover. (I bought mine in about 1975; I don't know whether more recent reprints include the fold-up plans or not.) The plans from Harold Hahn are also excellent. I'm not sure where to get them, though; Harold died a few years ago. There are lots of good plans in the works of David MacGregor.
The books of the great historian of naval architecture Howard I. Chapelle (The History of American Sailing Ships, The History of the American Sailing Navy, The Search for Speed Under Sail, and The American Fishing Schooner) contain hundreds of excellent drawings of American warships and merchantmen. Chapelle worked at the Smithsonian Institution, and left his original drawings to it. Finding the Smithsonian site on the Web where ship plan catalogs can be ordered is a bit of a challenge, but those catalogs contain all sorts of plans by other artists as well. You can order blueprints, custom-made for you when you order them, at quite reasonable prices.
Most of Underhill's aforementioned drawings are reproduced in his books, Deep Water Sail and Sail Training and Cadet Ships. And if you have any interest in French warships, check out the books by Jean Boudriot.
The official repository for original plans of U.S. Navy and Coast Guard vessels is the National Archives, which sells copies. The National Archives also has lots of merchant ship plans, but that's hit or miss. (There is no official repository of privately-owned ship plans in the U.S.) The original drawings of British warships - and lots of other British vessels besides - are held by the National Maritime Museum in Greenwich, which also sells copies (at astronomical prices). Be warned, though: the original plans for a ship may or may not include enough information to build a model. In fact most don't.
That's the tip of the iceberg; there are lots of other sources for plans. But that should give you some ideas.
I'll take the liberty of offering a few other unsolicited suggestions. The first is the one I've given to all newcomers who've asked me (and several who haven't): Don't try to build the world's best model of the Constitution, Victory, or Flying Cloud as your first scratchbuilding project. Ship modeling is an old hobby that's challenged people for centuries; if there weren't some value to having experience in it, the hobby would die. Longridge, if I remember correctly, spent at least ten years (after retirement) working on his Victory full time. I strongly recommend, as a first project, a relatively small ship in a relatively large scale. Leave the full-rigged three-masters till you get some practice under your belt. You won't regret it.
Two - take advantage of the books on the subject. There are some good books out there - and, unfortunately, some pretty awful ones. The ones I recommend include those of Longridge, Underhill, Hahn, Charles Davis (with some big reservations), and Wolfram zu Mondfelt (with some less serious reservations). Those I most definitely don't recommend include the ones by Milton Roth and Gene Johnson. If you want more suggestions on books, it would be a good idea to start another thread; I'm sure quite a few other Forum members would contribute to it.
Three - woodworking skills are just about essential to scratchbuilding, but they aren't the only ones. If you want to build a sailing warship, for instance, you almost have to have the tools to make metal turnings. (The aftermarket manufacturers may be able to sell you gun barrels that will fit, but that's hit-or-miss.) And rigging a ship model takes skills and techniques that, so far as I know, don't correspond with those in any other craft or hobby.
Four - Be really careful in you choice of woods. You didn't mention what species those boards from the 1880s are; if they're oak or heart pine, you're in for trouble. Woods used widely by serious scale ship modelers include basswood, cherry, boxwood, holly, pearwood, and (sometimes) walnut. White and yellow pine are marginal; balsa is useless.
Five - big isn't necessarily better - or more difficult. Take a look at the works of Donald McNarry: http://donaldmcnarryshipmodels.com/menu.html . His largest scale was 1/16"=1', and he frequently worked on scales as small as 1/64"=1'. His largest sailing ship models were about 18" long. When I look at his models, or photos of them, I'm tempted to give up. Your choice of scale should be influenced by several considerations: your available workspace, where you want to display the finished model, and - especially important - your eyesight. I was lucky enough to be born significantly near-sighted; when I was younger I had trouble recognizing people across the room without my glasses, but I could see just about anything on a model without magnification. My favorite scale used to be 3/32"=1'. Now, at age 62, I don't think I could work at that scale for long. (I have various magnifying gadgets, but nothing beats seeing your work with the naked eye.) If you have to struggle to see what you're doing, you won't have much fun - and fun, after all, is what this is all about.
Like many of my other posts, this one has gone on far too long. But I hope at least a little of it is useful. Good luck. It's a great hobby.