The simulated pregnant woman with a traumatic leg amputation didn't create any chaos, nor did the plastic patient who went into cardiac arrest on the way to surgery.

The excitement arose only when the ship's first full-scale medical rehearsal was nearly finished, and the vessel's Master ordered an abandon-ship drill for everyone onboard — fictional patients included.

With their arrival within helicopter range of Haiti expected overnight, the crew of the Navy's Baltimore-based hospital ship began a series of exercises Tuesday, using dummies and a fake medical script, trying to locate holes in the assessment and treatment plan they've put together during the last three days at sea.

They found some holes but say they're ready to begin treating earthquake victims, who arrived on the ship Tuesday night.

"We don't normally abandon ship in the middle of chest compressions," said Cmdr. Tim Donahue, head of surgery on the Comfort. "But we did fine. We're ready."

The Comfort's arrival in Port-au-Prince is anticipated as the first "level 3" treatment in the city, offering complex surgery and intensive care that is unavailable from first-response teams or makeshift field hospitals. In combat parlance, it is akin to one of the military's hospitals in Iraq or Afghanistan, such as the Army trauma center in downtown Baghdad — the closest full-service surgical center to the action.

The ship's two helicopters plan to begin flying today (Wednesday) at 7 a.m., and one of the first off the ship will carry an assessment team headed by Capt. Rich Sharpe, a trauma surgeon from the Navy hospital in Portsmouth, Va., and a veteran of four combat deployments. He was brought to the Comfort to serve not only as a surgeon but also because of his experience in establishing medical systems in unknown, potentially dangerous environments.

The ship will be working with military teams and relief organizations already in Haiti who have critical patients that need a higher level of care.

"We expect Haiti to be a lot like a combat environment," said Sharpe, who returned from Afghanistan Dec. 22.

"And this is how it always starts," he said. "Until patients are arriving, the actual – we call it battle rhythm – but the actual patient flow isn't obvious. It will be."

The precise number and types of patients to expect was still unclear on the ship yesterday, but crewmembers have been told to prepare to be overwhelmed.

With the addition of 350 new medical and service crew, who were expected in Guantanamo Bay, Cuba, overnight and to begin arriving on the ship today, the Comfort will exceed its capacity of 1,200 crewmembers. Officers on the ship were making arrangements for crew to share beds, a much-derided scenario known in the Navy as "hot-racking."

At the end of yesterday's drills, the ship's medical officers continued to tinker with the list of crewmembers they want onboard when the ship reaches full capacity – fewer surgical technicians, more nurses, for instance.

Officers also warned the crew to conserve water and have contemplated rationing, out of worry that care for Haitian victims could be compromised if the large crew consumes too much water. The Comfort can desalinate 300,000 gallons of seawater a day, but Port-au-Prince harbor is too polluted for drawing raw water. If the ship runs out of fresh water, it would have to pull the anchor and steam out to sea.

Crewmembers were also trying to maximize the space available for patient recovery and the rush of escorts and family members expected onboard. Workers began dismantling spaces reserved for a gym and public affairs to convert them into patient wards.

Lines formed throughout the ship of crewmembers waiting to get their daily dose of doxycycline, to ward off malaria. On the ship's fantail, petty officers were dunking uniforms in mosquito repellent – a requirement for crewmembers going to shore in Haiti.

The ship's main deck, where patients can proceed, front-to-back, through the ship's emergency room, x-ray room, operating theaters and intensive care wards, was abuzz with activity almost as if patients were already onboard.

Challenges included pre-packaging kits for intubating patients, deciding the maximum age for patients in the pediatric wards, and devising a system of creating makeshift I.D. numbers – the "pseudo-social" – for identifying Haitian patients.

The ship traditionally uses a system of having crew members wear different colored caps – red for the triage team, blue for stretcher carriers, white for pharmacy, etc. – to impose some organization on what crewmembers expect to be a chaotic process. By mid-morning yesterday, the doctors were still trying to find the caps.

Lt. Adam Cooper, an emergency room physician from Philadelphia and a Navy reservist, was called last week to serve on the Comfort. Like everyone else, he hadn't met or worked with his colleagues onboard before Friday night, and hadn't much contemplated providing disaster relief on a ship either. But he also, like everyone else, says the ship is ready.

"You don't know what's going to come off the helicopter, but we're used to that," said Cooper. "We're all just trying to put every ounce of effort that we can into it. And I think it's come together. We're ready."