For more than a year, Navy leaders worried that their manpower nightmare might come true, and now it has. A front-line ship is tied up in Norfolk, unable to go to sea, because there are not enough skilled sailors to run her.

The ship is the USS Canisteo, which won the nickname "Supership" last year for her heroic performance in the Mediterranean refueling and supplying U.S. warships there.

But the Canisteo cannot go back to the Med anytime soon, as originally planned. Her skipper tole his Navy superiors this would be unsafe because she has too few key people -- such as chiefs, boiler technicians and machinist's mates -- to steam safely for months at a time.

Navy leaders endorsed this judgment by Capt. Arthur H. Fredrickson, 44, of Hopkin, Minn. So, since returning from her overhaul at a Brooklyn shipyard last month, the Canisteo has been tied up here, an embarrassing symbol of the Navy's No. 1 problem -- the inability to keep experienced people in the ranks.

Navy officials at the Norfolk base can recall no similar situation. The nearest thing to it, they said, was in the mid-1960s when some ships were tied up so their crews could be rushed to the Pacific to serve aboard other ships off Vietnam.

To ease the current embarrassment, Navy leaders have scouted up two chiefs from staff billets to go aboard the Canisteo on Monday to take the ship out for a week's training. The objective is to get the Canisteo off the unsafe list.

However, Navy officials here acknowledge that even after the cram course, the Canisteo will not be able to return to the Med this July as originally scheduled. It will be late in the year, at best, after refresher training.

The way things are going, the Canisteo will be only the first active duty ship to be tied up for varying periods for want of a skilled crew. An internal Navy study states that the service is now 20,000 short of petty officers -- the most skilled enlisted people -- and will be 15,500 short in 1985 even if the ambitious goals for reenlistments in those categories are achieved.

Adam. Thomas B. Hayward, chief of naval operations, believes the only quick solution would be higher military pay, not the draft. Getting people into the Navy -- either as volunteers or as draftees -- is not the big problem, the admiral said. The problem is getting them to stay beyond their first tour.

President Carter evidently disagrees. Revising his defense budgets for fiscal years 1980 and 1981, Carter rejected the plea from the Joint Chiefs of Staff for big military pay increases.

Congress is more sympathetic and appears to be moving toward military pay raises. Meanwhile, Navy leaders are confronted with a steady exodus of skilled people and hard choices like docking the Canisteo.

The 644-foot-long, 36,000-ton Canisteo is a member of the active duty fleet -- not some ancient, rusty reserve ship used for training. She carries 143,000 barrels of fuel, 175 tons of ammunition, 250 tons of dry food and other supplies, 100 tons of meat and other refrigerated products.

The Canisteo is needed in the Mediterranean to keep Sixth Fleet warships there in beans, bullets and fuel. But would it be safe to steam across the Atlantic given the shortages of trained sailors? In an interview aboard his ship, Capt. Frederickson reconstructed why his answer was "no" when he addressed that question shortly after taking command on March 14. "

"Naval officers are lots of things," said Frederickson, a former jet pilot.

"One of the things we are is problem solvers. And you've got to solve them by taking the heady, rational approach."

Under ideal conditions, Frederickson explained, the Canisteo would have nine-boilelr technicians from 3rd class petty officer through chief, pay grades E5 through E9. These men run the power plant and, among other things, make sure the boilers do not blow up.

Tending boilers below deck is, hot, dirty work, with on-duty days at sea running as long as 18 hours. The Canisteo's power plant is 35 years old and needs constant attention. Boiler tenders in such old engine rooms do not work in air conditioned compartments. They stand under ventiliation ducts to get a gulp of slightly cooler air.

Not enough skilled boiler tenders are re-enlisting, to man the fleet, despite the bonuses for doing so. The Navy figured the Canisteo should get seven boiler technicians from those available.

Skipper Frederickson found himself with only two.

Likewise, the book calls for the Canisteo to have a maximum of 13 machinists mates. The ship's fair share of limited manpower would be eight. But Frederickson found himself with only six.

Machinists mates are skilled mechanics who keep the complicated rigging in working order, such as the gear used to transfer supplies to other ships in the fleet while steaming side by side in a rough sea. The skilled sailors are vital to a support ship like the Canisteo.

Skippers can offset such shortages of skilled junior petty officers if they have enough of the "old heads" on board, the chiefs who are the middle management of a ship.

But the Canisteo is short here, too. It has 12 when its "fair share" is 17. The two chiefs suddenly sent to his ship after The Washington Post interviewed him are only temporary.

"The chiefs are fundamental," said Frederickson. "They provide the leadership. They are the people who have the maturity, the people our junior people look up to."

"There's an expression," Frederickson added, "that it takes about five years to get about five years' experience. The higher skill positions are holding me back."

With Carter's decision to show the U.S. flag through large naval deployments in the Indian Ocean, the Canisteo had to go short. There are simply not enough in the Navy to go around.

As a stopgap, Frederickson said he will take his ship out from Norfolk to train his green crew -- rather than remain at the pier all the time like a beached whale.

But, as for going on a full deployment at sea, "we had to say, this is it," Frederickson said. "I'm officially rating the ship as unsafe to operate." It is not known how long it will remain in this category.

Was it embarrassing to be the first skipper to make that declaration?

"I don't look at it that way. It's a professional thing."

When the Canisteo had enough skilled sailors aboard, it won seven out of seven performance competitions at sea as well as the name "Supership" for its refueling in the Mediterranean early last year.

Escorting a visitor down the ladders to the gangplank leading off his ship, skipper Frederickson pinned a yellow and black button on the visitor's lapel. It had a big "E" for excellence, recalling happier times. The button says: "USS Canisteo, Number One Ship in the Fleet."

On the same day, by coincidence, Adm. Hayward was telling an audience in Washington:

"The hemorrhage of talent represented by the loss of mid-grade petty officers and officers today is an issue that sooner or later will become a national one. In my judgment, it will be sooner rather than later."