IF IT'S winter cruise time, it must be the Caribbean, right?

Nyet, nyet.

The season has started, of course, but if you have a sudden craving for diversity, how about a trip between Hong Kong, Japan and Nakhodka, a few weeks of voyaging from England to North Africa, or selling from Odessa to Piraeus, Beirut and Alexandria?

If those don't grab you, there's also Vienna-Yalta or Singapore-Australia, all brought to you by the same folks who now operate the biggest fleet of passenger ships in the world: the USSR.

Yes, you heard it right, and never mind that cruising historically has had more than a slight connection with "class." As of now the Russians have more than 80 ships flying the "Black Sea Shipping Company" flag, as well as a long list of others operating under foreign contracts and through additional Russian companies. All can be booked in the United States through March Shipping Corp., 1 World Trade Centre, Suite 5257, New York, N.Y. 10048.

And of course they'll go to the Caribbean this winter from New Orleans, and next spring from New York and Philadelphia.

The second piece of news is that the Russians offer slightly cheaper fares than virtually anybody else, and throw in two bonuses: no tipping and free medical service should you need it. Of course, there are other differences as well - not all as thrilling.

To see what cruising a la Russe is like, when the Reds sailed in the sun-wet (well, they did) from Freemantle, Australia, to Singapore, I went with them. We were seven days on board the M/S Turkmenia.

There were no stopovers, but nichevo (never mind), as we learned to say in the daily Russian-language lesson that struck me as an imaginative addition to the usual cruise lineup of bingo, "crazy games night," horse racing." fancy dress parade and movies.

There was, as well, some thoroughly vulgar capitalist-style entertainment - which is to say that on two evenings, the music salon's dance floor rocked with leggy Australian showgirls in plumes and cut-to-there costumes. The crew, obviously devotees of the arts each and every one, broadmindedly jammed up for places outside the salon's open doors. In the "where will it all end?" department, one of our films even turned out to be a James Bond adventure.

We did get back on track the last night out with Russian songs and dances winningly performed by crew members.

Things, indeed, turned out better than I initially dared hope after an opening encounter with the ship's purser. Like the cabin and dining room stewards, the purser was a woman, and she started at me in surprise when I braced her with the question, "Is there food service in the cabins?"

"Why?" she asked. "Are you sick?"

"No," I admitted, though suddenly suspicious that I might be soom.

"Only if you're sick," she said in a doomsday voice.

I persisted in the faint hope that we had only a communication problem.

"How about breakfast?"

"Why?" she asked. "Are you sick?"

I persisted in the faint hope that we had only a communications problem.

"How about breakfast?"

She looked astounded and sounded impatient.

"You go to the restaurant."

"But I like to sleep late," I said, finally owning up to my bourgeois way.

That's not good for you. You should get up."

I got up, but largely because the public address speaker couldn't be turned off and announcements came booming in between 9 and 9:30.

I shared a two-berth upper deck cabin with bath, one of the Turkmenia's most expensive at $360 or roughly $60 per night, comparable to the lowest price on many American-market cruise ships. Decoration was, like the Turkmenia's public rooms, all Motel Modern.

The Price of the new edition of a booklet, "Travel for the Patient With Chronic Obstructive Pulmonary Disease," mentioned in this section last Sunday is now $1.25 postpaid, according to the publisher, George Washington University.

It may be ordered by writing to the Rehabilitation Research and Training Center, George Washington University Medical Center, Ross Hall, Suite 714, 2300 I St. NW, Washington 20037. Checks should be made out to the university.

Gladys, my 73-year-old English cabinmate and an old hand at cruising took in the lack of bedsprings, fascial tissues, soft toilet paper and full mirror, checked the presence of muslin sheets and then, waffle-weave towels, and then cheerily uttered what became her theme song, "Oh, well, mustn't complain, mustn't complain."

Four mornings later, though, she used a less even-tempered tone:

"Mustn't complain, but you'd think they'd give us fresh sheets and towels at least once. I just asked, though and do you know what they said? They said no!"

They said "no" but they apparently meant "yes" (Language was a problem; the pursers spoke some English but the cabin, dining room and bar staffs had little or none.) Later that day we did get our one change of linens. True, the brochure had promised "the amenities of a well-appointed hotel" but it didn't really come to grips with what constituted "amenities"; we did without vacuuming and bathroom cleaning. Quite often we did without deck chairs, too, as there were only 30 for our group of more than 300.

Among other things Gladys didn't complain about was the dress of the other passengers. SHe kept up good luxury cruise ship standards but the rest of us - well, jeans or cutoffs and T-shirts even went to dinner.

The passengers were mostly Australians, plus a handful of British, and roughly 75 per cent were well under 40, a surprise since most cruises draw an inverse age ratio.

It was, in fact, a convival crowd that thoughtfully passed the world on what to order and what to avoid at meals. Normally there was an appetizer, soup; a choice of two main dishes, salad and cheese, fruit or a sweet for dessert. Good Australian wine and freshly baked bread were pluses. However, the kitchen's chief claim to fame was inventiveness. I would certainly give it one prize in the "daily disguise for hamburger" category, and another for "creative salads from recycled leftovers."

The Turkmenia's master also proved inventive about additional sources of revenue. Unlike other cruise ships that stuff you day and night, the Turkmenia served three meals and afternoon tea, period. If you were still hungry there was junk food and ice cream for sale at the pool bar. For music, apart from the live programs, there was a cash jukebox in the lounge bar. Hairdressing was at U.S. level prices. Use of a washing machine and iron were free, though, and much in demand since there were no laundry or valet services.

In addition, the Australian cruise staff of three handled the sale of tickets for a vodka-tasting session ($2) and rented popular novels and games.

According to Frances, an English nurse who had sampled several other Russian cruise ships, the Turkmenia was "not typical." On her others, she reported, there was more propaganda (in the form of movies and literature left in cabins), but there was also better food and more free amenities.

The Soviet ships cruising from American ports are logically the most Americanized. The Odessa and the Kazakhstan both offer early coffee, continental breakfast that can be served in the cabin (or regular breakfast in the dining room), a midmorning cup of bouillion, luncheon, afternoon tea with a variety of tea, dinner and a mid-night buffet. All cabins have baths and both ships have a pool, a gym, sauna, library, casinos and besides entertainment, offer lessons in balalaika and the Russian language. There are American and Russian cruise staffs; key cruise members speaks English and linens are changed every other day.

I suspect, however, that the big attraction of a Russian ship is its Russianness. The Turkmenia was a letdown not because its Soviet-style comforts didn't come up to Western cruise standards but because it failed to replace luxury with camaraderie: the captain and other mixing it up between passengers and generally unsmiling crew. As far as I could learn, there weren't even many conversational exchanges, although on our last night out, I got lucky and became a party to one by asking an officer what time we expected to make port.

"At I o'clock because that's when we're scheduled to get docking space," he replied in only slightly accented English. "But we're early now, so we'll probably stop the engines for awhile tonight."

"Ah," I said sweetly, "is that when we meet the submarine"?

"Yes" he answered, grinning and walloping the ball back into my court, "we get together each trip and trade them women."

I do hope it's only the women. They need HIM right where he is.