How do shipyard workers complete seemingly impossible tasks, such as painting the ship's bottom or making adjustments to propellers? Every two or three years, a ship goes "off the grid," so to speak, making a pilgrimage to a shipyard for maintenance. In industry parlance this process is called "dry-docking" -- which, as the term suggests, means that a ship is actually taken out of the water and hoisted onto blocks in a big, waterless basin.

Most ships visit dry dock (well-known sites include Hamburg's Blohm + Voss and Freeport's Grand Bahamas Shipyard) for regular, mechanical upgrades or maintenance. However, every once in a while a cruise line will commit to a major refurbishment that includes significant alterations to passenger areas, too. Celebrity Cruises' Celebrity Constellation underwent just such a revitalization in the spring of 2010.

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Constellation is the first of Celebrity's Millennium-class ships to undergo a series of planned enhancements based on features that have proven popular on its newer Solstice class of ships. Now, Constellation, built in 2002, has a sleeker ambience, thanks to the addition of new venues such as the Tuscan Grille; Crush, an ice bar; and Cellar Masters, a wine bar. There are fresh color schemes throughout. All staterooms received a major re-do, with new bedding, loveseats, and flat-screen televisions. The ship is essentially reborn.

All this -- plus the regular maintenance -- was done in merely two weeks. Cruise Critic Editor in Chief Carolyn Spencer Brown was invited to spend the final few days at the shipyard (as well as a couple of days transiting from Hamburg to Constellation's first embarkation port in Amsterdam) for an exclusive look at the ship's final stages of transformation.

Come along on the journey as we show you the three key phases of such a project (clearing out the old to make way for the new, mid-way through construction, and the finished -- or near-finished -- effort).

Phase 1: Clearing out the Old to Make Way for the New
Before climbing aboard on a cold, clammy spring day in Hamburg, we knew that Celebrity Constellation's dry-dock session here would be unusually intense. When originally planned, the period at the shipyard was meant to simply make repairs and perhaps make minor changes to decor. Two weeks is generally plenty of time -- but remaking an eight-year-old ship to look more like the hipper, more contemporary Celebrity Solstice isn't easy.

In an interview onboard, Lisa Lutoff-Perlo, Celebrity Cruises' hotel operations chief, told us the biggest challenge is finding space to add the upgrades -- multiple dining venues, cabins with trendy decor, cutting edge coffee bars, lounges and performance venues -- to a ship that's only two-thirds the size of Solstice and it siblings. And it's hard to imagine that building out new rooms, recovering chairs, laying carpet, making beds and filling mini-bars, and giving the ship a really thorough cleaning can be accomplished in the two days that is left before Constellation picks up passengers in Amsterdam.

But since Lutoff-Perlo seems relaxed -- and crew and contractors, while working intently, don't seem to be panicking -- I figure it'll probably get done....

Click to Launch Phase 1's Slideshow

Phase 2: It's Starting to Come Together
As intriguing as it is to watch the construction process of a ship that's essentially being redesigned, what was even more fascinating for me was life onboard throughout the process. There were no passengers on Celebrity Constellation -- only crewmembers, contractors from the various companies hired to refurbish venues, a handful of Celebrity Cruises executives, and a pair of journalists (my husband, Teijo Niemela, who's editor of Cruise Business Review, a business to business magazine, and me)....

Click to Launch Phase 2's Slideshow

Phase 3: Before and After
Having cruised on Constellation some years ago -- and now watching its re-creation in May -- it occurs to me that Celebrity's design team walked a fine line. Can you really adapt a ship design that's a decade old to new times while still maintaining its original ambience? As popular as Solstice is, not all passengers are one-size-fits-all travelers. As one Cruise Critic member has said, "We were very pleased with the Solstice and Equinox, but are looking for a more classic Celebrity experience. Have they made Constellation too much like the Solstice class ships?"

You tell us. In the meantime, as we wrap up our Constellation refurbishment adventure, we'll take you down memory lane (and bring you back to the present again) with our "before and after" collection.

Click to Launch Phase 3's Slideshow

--Some images taken during and after dry dock appear courtesy of Teijo Niemela. All others appear courtesy of Celebrity Cruises.