When the megaship Ovation of the Seas sails into Sydney and docks at the Overseas Passenger Terminal (OPT), a military-style operation swings into action.

In 10 hours, some 4,900 passengers disembark and another 4,900 step aboard. That means 10,000 pieces of accompanying luggage have to be unloaded and another 10,000 loaded. And that is not all.

Down in the bowels of the ship, forklifts are hard at work with crew, dock workers and suppliers frantically loading thousands of kilograms of food.

An army of housekeepers among the ship’s 1,500 crew members will have to clean the 2,091 cabins and bathrooms, remake the beds and get the ship’s 16 passenger decks, 18 restaurants and 12 bars and lounges spick and span before the next 4,900 passengers embark.

This is what is called a “turnaround day” – and speed is everything. Just as commercial aircraft make money flying not sitting on the tarmac, keeping ships at sea is crucial to a cruise ship’s bottom line.

Royal Caribbean’s newest ship, Ovation of the Seas is spending the summer wave season homeported in Sydney. And preparing for the ship’s arrival at the OPT on December 15 was a big test for the cruise line and the Port of Authority of New South Wales.

Both put in a year of planning before Ovation’s arrival Down Under.

While RCL fine-tuned and road-tested the huge logistical operation, Port Authority NSW’s general manager, cruise, John McKenna, led a 10-member delegation including immigration officers, ground handlers, stevedores and customer-service executives to Singapore to learn how their counterparts handled two turnarounds of Ovation.

“The sheer size and complexity of Ovation’s turnarounds was mindboggling,” Mr McKenna says.

After spending a week in Singapore, they ordered the installation of two concrete bollards at the OPT, at the cost of about $1 million, to ensure the 347-metre long, 41-metre wide, 168,666 tonne Ovation could be safely secured.

The first and last day of any cruise are the busiest time for the ship’s crew. According to a New York Times article, Royal Caribbean attendants are responsible for up to 17 cabins each and have a precise list of tasks to perform on turnaround day.

They first have to take out the dirty linen and towels and line them up in the hallways. Rooms are then dusted and wiped. It is estimated that 189 housekeepers can get about 2,700 cabins ready by noon.

This will happen in Sydney eight times while Ovation cruises from the OPT on three- to 15-night itineraries around Australia, New Zealand and the South Pacific, from December until February 2017.

At the end of each cruise, passengers and their luggage have a two-and-a-half hour window between 7am to 9.30am to vacate their cabins and disembark.

The ship must then be ready for new passengers to start to check-in at midday. Everyone must to be on board by 5pm before the ship sails away at 6.30pm.

Passengers can now check-in using mobile iPads instead of queuing at counters. Port officials have been deployed at the OPT to help embarking passengers and staggered boarding times have been introduced to avoid the bottleneck of passengers boarding at the same time, Mr McKenna says.

Access to the northern end of Circular Quay has been opened to allow up to seven trucks to unload supplies.

“The fact Ovation will visit Sydney eight times this wave season is testament that RCL has confidence in our ability to handle megaships,” said Mr McKenna. “We are open for business. We want the world’s biggest ship, Harmony of the Seas to come here.”