This December, Royal Caribbean International will introduce Oasis of the Seas, the 225,000-ton, 5,400-passenger super-megaship that will wrest the "world's largest" title away from the line's own 160,000-ton Freedom-class vessels.

Two weeks ago I spent a couple days tromping around the still-under-construction vessel at Finland's STX Shipyard, and the visit confirmed what my research had already made me suspect: Oasis will change the paradigm for new megaships, and it will do so for the better. The ship's form, consisting of a super-wide hull surmounted by a split superstructure -- two parallel "buildings" to port and starboard, with a wide, open-air canyon down the middle -- simultaneously increases the space and potential for onboard amenities while also substantially eliminating the kind of enclosed, labyrinthine arrangement that have made other mega-ships seem so artificial. The ship in fact reestablishes a connection with the sea and sky that's been lacking in many other recent megaships, leavening with sun and air an atmosphere that's seen too many enclosed, track-lit public rooms.

So yes, I think Oasis will change ship design for the better -- but that said, an analysis of the current shipbuilding market gives me reason to believe that paradigm shift may take a while to manifest.

Take this fact, for example: STX's yard in Turku, where Oasis is being completed and its sister ship Allure of the Seas is under construction, currently has no new cruise ship orders on its books. Business has also fallen off at Europe's other shipbuilders, with some estimating that total cruise newbuilding business in Europe has fallen 97% for the year. With the Great Recession still kicking consumers' butts, cruise lines are having to work hard to fill their existing berths, so the flood of newbuilding in which those lines have been engaged for more than a decade seems finally to be slowing, though not yet coming to an absolute screeching halt. Currently, there are 20 midsize and mega-size ships on the construction books following Oasis, most of them sister ships to existing classes.

Take a look: In early 2010, Costa will take the keys to Costa Deliziosa, a 92,700-ton sister ship to Costa Luminosa, and MSC Cruises will accept delivery of the 86,600-ton MSC Magnifica, the fourth ship in its Musica class. Toward summer, Celebrity will introduce the 122,000-ton Celebrity Eclipse, the third ship in its Solstice class, and Holland America will introduce the 86,000-ton Nieuw Amsterdam, a sister ship to last year's Eurodam. Other sisters follow: MSC's Musica-class Meraviglia, Costa's fourth Concordia-class ship, Carnival's Carnival Magic (sister ship to this fall's Carnival Dream), and Celebrity's fourth Solstice-class ship in 2011, MSC's Favolosa (the sixth Musica-class sister), Celebrity's fifth Solstice ship, and Costa's fifth Concordia ship in 2012.

All of these vessels, fine though they might be (especially Celebrity's Solstice ships), still follow the basic model on which megaships have been built since the concept fist came to the fore in the late 1990s. Not that there's anything wrong with that, but the point is that while Oasis and Allure might really be game changers, that game is guaranteed to go on for quite a while just exactly the way it was before they came along. Change, in this instance, will be slow. Not that there aren't some interesting newbies coming down the pike, most significantly NCL's 150,000-ton, 4,200-passenger Norwegian Epic. Debuting in May 2010, the ship will offer some amazing-looking sports and recreation amenities, as well as an outdoor nightclub, a cool adults-only pool area in the stern, and high-style "studio" cabins for budget-conscious hipsters. Disney will also be introducing its first ships in more than a decade, the 128,000-ton, 2,500 passenger Disney Dream and Disney Fantasy, which appear in 2011 and 2012, respectively. Details aren't out yet, but Disney is Disney, so they should be entertaining. On the quiet end of the spectrum, Cunard will launch its new Queen Elizabeth in 2010, retreating from the bulk of Queen Mary 2 back into the megaship safe zone at 92,000 tons and 2,092 passengers. Also in 2010, Oceania will please those who prefer midsize ships with its new 65,000-ton, 1,260-passenger Marina, and an unnamed sister scheduled to follow in 2011.

Conclusion? Between the current backlog of ship orders, which largely rely on existing designs, and the reluctance of cruise lines to stretch and expand in the face of soft bookings and the need to service existing debt, Oasis and Allure of the Seas will probably be the world's largest cruise ships for some time to come, and also its most unusual and innovative. Unknowns regarding the timing, scope, and breadth of whatever recovery the world's economy eventually sees, combined with any number of other variables, make it impossible to predict when or whether other new vessels will follow in their design footsteps.

Last word, at least for now? How about this, from the polar seagoing opposite of the megaship world: Over the next few years, two companies will launch brand-new sail-powered ships, which will carry just a few hundred passengers on itineraries virtually guaranteed to eschew the mainstream megaports for quieter, more "authentic" travel destinations. In summer 2010, Sea Cloud Cruises will launch the 136-passenger Sea Cloud Hussar, whose three masts will fly 28 sails, and whose 69 cabins will be appointed in traditional, woody yacht style. The ship is currently under construction at the Factoria de Naval Marin shipyard near the town of Vigo, Spain. Star Clippers also has a new sailing ship on the drawing board, an as-yet-unnamed 296-passenger barque modeled on France II, which was the world's largest sailing vessel when she launched in 1912. The plan is for the ship to measure 518 feet long, fly 37 sails, and have an ice-class hull that will let her sail anywhere in the world. Last I heard, the ship was targeted for introduction in 2011.