How much will a cruise really cost you?

Once you've paid your fare, most of your expenses are taken care of. That's one of the things that makes cruises popular. Your fare includes the cost of ship transportation, sleeping accomodations, all meals and entertainment on board.

But a number of other charges are not included in the fare. These are "extras," and you pay for them out of your pocket. Here is a rundown on these costs. Total them and you'll have a good idea how much money to bring on your cruise.

GRATUITIES: This is the biggest "extra." Tipping is at each passenger's discretion, but cruise lines issue guidelines to their passengers (Holland America is the only line that has a "no-tipping policy). On Caribbean cruises, the usual recommendation is $5 per day per person, distributed as follows: Room steward, $2; dining room waiter, $2; busboy, $1. Tips are given in one lump sum on short cruises, usually on the last night. Bar waiters and any others who provide services should be tipped as you would ashore when the service is rendered. Wine stewards should be tipped about 15 percent of amount of the drinks or wine ordered, either at the time service is rendered or at the end of the cruise. If a maitre d' gives special services, he too should be tipped. You should adjust your gratuity up or down according to the quality of the service.

PORT TAXES: Like death, they're inescapable, and like everything else, they keep going up. They vary according to the number of ports on the itinerary. One line which calls at four ports currently assesses passengers $17.

BAR BILLS: Another big expense for most passengers. You must pay for liquor, beer and wine you consume, but their cost aboard ship is lower than ashore because alcoholic beverages are tax-free on the high seas. Prices of drinks vary from ship to ship. Beer, 75 cents to $1; standard drinks, $1 to $1.40. Premium and/or imported brands may command higher prices. Many ships offer daily drink specials at lower costs.

SHORE EXCURSIONS: At ports of call, you'll want to tour the attractions ashore. You can purchase guided tours on board ship, buy them ashore or do your own tour without any guided arrangement. Cost of a tour purchased on board is usually higher than the same tour purchased ashore, because the cruise director tacks on his commission. However, ship-purchased excursions offer greater convenience and security (the ship won't leave until the tour returns). Prices of tours also vary fro ship to ship. Here is a sampling of some excursions sold aboard ship: Tour of Dunn's River Falls, Jamaica, from Ocho Rios, $11; Cap Haitien, Haiti, tour to mountaintop fortress by bus and horseback, $17; city tour of Charlotte Amalie, St. Thomas, $7.50; tour of Cozumel, $26. All prices per person.

GAMBLING: Any wagering, of course, comes out of your pocket, and hopefully goes back into it. Nearly all ships have slot machines; some have full casinos. In addition, most stage parlor gambling games like bingo and horseracing. Cruise staffs take a large cut from these, so the odds are stacked against you.

DECK SPORTS: Mostly free, but you will have to pay for expended items in most cases. Traps, for instance, run two or three for $1; golf balls, if driven into the sea, about three for $1. Deck stewards expect to be tipped.

SHIP-TO-SHORE TELEPHONE: $15 for the first three minutes, $5 for each additional minute.

BEAUTY SHOP, BARBER, ETC.: A wash and set usually runs about $8.50, a haircut for men $6.50 to $8. A 30-minute massage is $12, a sauna $3 on one ship.

PHOTOGRAPHS: Souvenir pictures taken by ship's photographer are usually sold at $3 to $3.50 each.

MEDICAL SERVICES: Consultation with the ship's doctor regarding ship-related ailments, such as seasickness, is usually free. Doctor's services for other ailments, or for services rendered outside regular office hours, may involve a fee of from $10 to $15. Any inoculation also incurs a fee.

SHOPPING: You're on your own, of course. Every ship has at least one duty-free shop, but you'll find their prices usually higher than those at ports of call. Best shopping spots in the Caribbean: U.S. Virgin Islands, St. Maarten and Curacao.

BABYSITTING: If available, cost will run $2 an hour and up, with a minimum.

PERSONAL TRANSPORTATION: Taxis or buses from ship to town are your responsibility.

PARKING AT EMBARKATION PORT: At Port of Miami, $2 a day, if you leave your car there for the duration of the cruise.