The assignment beginning Monday will see the second in line to the throne spending much of his time trolling the West Indies aboard the HMS Iron Duke, a frigate on hurricane relief duty and counter-narcotics patrol.
Rear Admiral Robert Cooling, assistant chief of Naval Staff, said William "commendably wanted to be as close to the front line as possible." But officers decided he could learn more in a short time by serving on the Iron Duke than by being sent to the Persian Gulf, where the Royal Navy is engaged in a number of operations.
There was also concern that placing William, 25, in the Persian Gulf might draw unwanted attention from Britain's enemies.
"We clearly wouldn't have put the prince in the way of a particular threat, and we wouldn't want his presence in a warship in a particular region to have drawn attention from those who might not wish him well," Cooling said.
Deployment of William's brother, Prince Harry, to the front lines in Afghanistan had to be cut short this spring after a news embargo was broken and it was revealed he was serving there.
Senior officers stressed in a pre-deployment briefing that William will not receive special treatment during his Navy assignment, which will include shoreside training followed by a five-weeks at sea.
"The rules that will apply to Prince William will be exactly the same as the rules applied to any junior officer," Cooling said.
However, he said, the prince probably would not take part in boarding parties if the men are likely to come under fire while attempting to intercept drug shipments.
William is an officer in the Army, but he has been spending time in other branches of the service to round out his military experience.
He made headlines during his stint with the Royal Air Force, landing a Chinook helicopter on his girlfriend Kate Middleton's lawn and using the military chopper for other questionable trips, including picking up Harry and flying to a stag party on the Isle of Wight.
On the Iron Duke, William is scheduled to spend time in every department, including weapons engineering, logistics, operations, and the ship's helicopter flights. There will be no special accommodations for the prince, who is expected to bunk with other junior officers, and there will not be special security while he is at sea, Cooling said.
Commander Simon Huntington said the prince would in essence receive an abbreviated version of the normal two-year training most young officers receive.
Richard Kemp, former commander of the British Armed Forces in Afghanistan, said the training with all branches made sense for William in light of his future role as head of the armed forces.
"It's very good that at this stage he has a chance to experience all of this and get to know some of the people who will be leading the military and see some of the difficulties that they face," Kemp said.
The brothers are continuing a family tradition of Armed Forces service. Their grandfather, Prince Philip, had a long Navy career, as did their father, Prince Charles, and their uncle, Prince Andrew, who flew a Sea King helicopter during the Falklands War.
Cooling said all William's Navy flights would be "purely business." He noted that in many cases William will be flying as a passenger because he is not yet qualified for a variety of helicopters.
The Navy also plans to give William firsthand experience on a mine hunter during sea training operations, and he will be submerged in a nuclear attack submarine while it seeks to attack and evade ships and helicopters during training operations, officers said.
On the Iron Duke, William will be expected to cope with the confined spaces that define naval life and will also be required to serve on the 24-hour watches required at sea.
"These warships are not like cruise liners," said Cooling. "It's going to be a lumpy ride. He doesn't know if he's susceptible to seasickness, but if he is, there are pills that can help. It's nothing to be shy about. It happens to the best of us. Nelson got seasick."
Seasick or not, no one is suggesting that the future king will have to do kitchen duty.
Someone else will have to wash the dishes and peel the potatoes.
