The invasion of the City Dock and harbor began in the darkness, at exactly 12:01 a.m. Monday.

First came a fleet of flatbed trucks, met by the work crews standing ready to unload the ticket booths and trash cans, tents and temporary buildings.

Then, hours later, shortly after sunrise, the battle began in earnest, with the eruption of heavy machinery. Workers started driving pilings into the water, more than 50 in all, forming the foundation for a network of 300 floating docks that would make up a temporary marina covering more than a mile. At the same time, others were laying the roughly 57 miles of underwater cable needed to wire the area for electricity.

By afternoon, a small armada of roughly 250 sailboats approached from the east, entering the harbor in precise order to fill their assigned spaces in the burgeoning temporary marina. So too, in predetermined fashion, rose the exhibit space on land.

"The military calls that combat loading," said Rick Franke, manager of the Annapolis Sailing School, which helps put the show together.

The battle was to prepare Annapolis, in just three days, for the 35th annual United States Sailboat Show, which begins at 10 a.m. today and runs through Monday. When it's over, the same work crews -- a mix of sailing school and boat show staffers, as well as temporary workers -- will transform the scene to accommodate the 33rd annual United States Powerboat Show, which runs Oct. 14-17. About 50,000 people are expected to attend each of the shows.

Preparing for what is billed as "the only major in-the-water show that doesn't take place in a natural marina" is daunting, Franke said.

"It's very much like putting together a circus," he said.

Despite the frantic, last-minute effort required this week and next, the boat shows are actually the product of a year's worth of work. The sales staff began laying out plans last November. By December, mailings were being sent to exhibitors, asking if they wanted "more space or different space" in the coming year, Franke said.

Since the late 1990s, that planning has become more high-tech. The exhibitors are sent computer drawings of potential exhibit space. "It's been a great step forward," Franke said.

Manufacturers see the fall show as a chance to unveil next summer's product line. The demand is so great that "we're turning boats down," said Jim Barthold, the general manager of Annapolis Boat Shows Inc.

This year, for the first time, an annex has been set up so spectators can view powerboats in a small display area at the Navy-Marine Corps Memorial Stadium.

The exhibitors pay about $1,000 for a booth, or roughly $6 a square foot for space on land or water. In return, they can show the latest models to serious customers. Deposits are made and contracts are signed.

"The shows are very much about people committing to buying a boat," Barthold said.

That demand means an increased workload for those who put the show together. The temporary marina has been stretched almost to its limit for the bigger powerboat show.

"We're getting into deeper and deeper water all the time, and it gets more difficult," Franke said.

The workforce for the shows gradually increases from about 10 in the winter to 80 or more when the event begins, Franke said.

In late summer, preparations begin in earnest. The sailboats and powerboats that will be featured begin arriving at temporary quarters in marinas. By the beginning of September, equipment -- everything from the temporary docks to the ticket booths -- is ferried from storage in Owings to Annapolis.

The equipment is taken to two staging areas. One is at the marina, where the floating docks are inspected and then assembled in configured sections, so that they can collectively -- and rapidly -- be molded together in the water in the days before the show. The second staging area, which is far larger, is at an old sewage treatment plant nearby, where the crews begin constructing the tents, also in sections.

The workers must proceed quickly because of severe time constraints. Though some equipment can be moved in on the weekend before the show, the organizers do not officially assume control of the dock and harbor until a minute after midnight Monday, and the setup must be essentially completed by 8 p.m. Wednesday.

"That's the absolute drop-dead deadline," Franke said.

Before then, staff members must coordinate the arrival of the boats in the harbor, making sure exhibitors follow an assigned "load-in schedule."

"If you're not there . . . you wind up somewhere else in the show. . . . It's a use-it-or-lose-it situation," Franke said.

The turnaround between shows is equally frantic -- "controlled chaos," Franke said. The sailboat show closes at 5 p.m. Monday. Out go the sailboats; in come the powerboats that night.

"You get all of those boats out of there in three hours," Franke said.

Then, when the powerboat show ends, the chaos begins again.

"We have to clear the dock in two days," he said.

When the work is finished, the organizers rest.

"Most of us take a week or two off," Franke said.

And then it's back to work, preparing for next year's show.

Sharon Kleinpeter, above, counts tent frames at a staging area. Her husband, Burt Kleinpeter, left, works on show signs near the dock. Ben Vehslage, below, assembles a floating dock at the Annapolis Sailing School.Joan Antolik, Bill Buhann, center, and Chris Summers ready a Seaward 26. Below, a view of the State House through masts and banners.Danny Vargas cleans a Saga 48 before the United States Sailboat Show, which begins at 10 a.m. today in Annapolis.