While Royal Caribbean is forging ahead with a "size rules" mantra for its upcoming Genesis new-build (due out in fall 2009), the line hasn't forgotten about its (slightly) smaller offspring. According to Aker Yards, the shipbuilding company putting together the first Genesis-class ship as well as Independence of the Seas due out in April, RCI has signed a "Memorandum of Understanding" to build a fourth Freedom-class vessel.

Still subject to finalization -- RCI board approval, hammering out of details of the contract, working on financing etc. -- the as-yet-unnamed Freedom-class vessel is scheduled to be delivered during the second half of 2011.

Though no contract has yet been signed, "It's pretty much a done deal," says Teijo Niemela, publisher of Cruise Business Review, an industry magazine.

The fact that RCI will likely produce another Freedom-class ship rather than focusing their attention on an even larger, post-Genesis design isn't surprising.

Instead of looking for more Genesis-class ships, says Niemela, Royal Caribbean is looking for a greater number of new ships to accommodate source markets. And the fact that RCI has already successfully launched two Freedom-class vessels, with a third set to debut two weeks ahead of schedule, means that building a fourth will make sense economically. At this point, assembling a Freedom-class ship is nearly down to a science.

There are other drawbacks to bringing too many Genesis- or post-Genesis sized ships to market. Niemela goes on: "It's quite limited ... where you can deploy [Genesis vessels], but Freedom-class ships are much more flexible ... look for example at their European deployment with Independence this year." Currently, it only takes one hand (and maybe a thumb) to count the number of ports ready to handle Genesis.

The announcement is consistent with other lines that have debuted their most massive, amenity-laden offerings to date, and then returned to build either ships based on well-established design platforms or new ships on smaller platforms. After a pair (one more on the way) of 114,000-ton, 3,780-passenger Concordia-class ships, Costa will return to a more mid-size offering when the 92,700-ton, 2,260-passenger Costa Luminosa debuts in Spring 2009.

MSC is following suit. After the launches of the 133,500-ton, 3,300-passenger MSC Fantasia (November) and Splendida (spring 2009), a duo of largest-ever offerings from the Italian line, MSC Cruises will return to its more moderately sized Musica-class ships when the 89,600-ton, 2,550-passenger Magnifica launches in the fall of 2010. MSC Poesia, set to launch this spring, was actually ordered after the Splendida and Fantasia giants were announced.

What else is coming down the pipeline? Take a look at Cruise Critic's Future Cruise Ship Orders feature.

--by Dan Askin, Assistant Editor