Idyllic Caribbean cruises call for careful planning

While it sounds delightfully languid and luxurious, cruising the Caribbean does require several hard-nosed decisions: where to sail and when, what kind of boat to charter and from whom, and, of course, how much all this Rockefelleresque fun in the sun is going to cost.

One of the easiest ways to pare your options is to talk with friends who have already sailed the Caribbean's azure waters. Unfortunately, ''bad news often travels faster than good news in this business,'' according to one charter company owner, and you may find yourself loaded down with a list of ''don'ts'' rather than ''dos.''

Yachting and cruising magazines are another way to familiarize yourself with the general boating terrain. Often these publications will feature special sections on the Caribbean that list available charter companies and their current prices.

First, decide where you want to sail - the Bahamas, Virgin Islands, Lesser Antilles, or the western Caribbean - all offer slightly different cruising experiences. A popular sailing ground with Americans because of their proximity, the Bahamas are a collection of roughly 700 flat, often uninhabited islands whose numerous coral reefs, sand banks, and small bays are perfect for ''gunkholing'' in shallow draft boats. The Abacos, Exumas, and Bimini are generally the most popular spots in this archipelago, where winds normally blow from the east but can be blustery during winter months.

For more consistent conditions most sailors head south, deeper into the Caribbean. There the Virgin Islands, a closely spaced chain, temper the ocean swells. Numerous bays and anchorages, particularly in the 40-island British Virgin Islands (BVIs), make for relaxed and beautiful sailing year round. Indeed , this is the unofficial center for charter boat operations in the Caribbean.

The BVIs alone boast some 300 yachts (not including the boats chartered through private brokers) available through half a dozen reputable companies. Despite a recession that badly rocked the industry in 1981 and '82 and caused some charter operators to go under, many companies have expanded their operations from bases in the Virgin Islands into the Lesser Antilles, where larger, far-flung islands allow the open-ocean sailing that appeals to intrepid sailors who enjoy a good workout.

For the proverbial off-the-beaten-track sail, more adventurous yachtsmen may prefer the relatively solitary waters of the western Caribbean. Here, off the coast of Belize and Honduras, extends a 120-mile-long barrier reef considered one of the world's best for diving and snorkeling. Still relatively undiscovered , these waters offer few anchorages and yacht rental choices remain slim.

Once your geographic choices have been narrowed you can start shopping for your yacht company. Words of advice: Choose wisely. Even charter company operators admit that theirs is a fluky industry where the profit is not in the actual chartering but in the original sale of the yachts to independent owners.

Two trade associations have recently been formed - the BVI Bareboat Association and the Caribbean Charter Boat Association - for the express purpose of alerting consumers to financially reliable companies. More than one charterer has found that his supposedly refundable deposit was literally gone with the wind when the leasing company suddenly went bankrupt.

Unless a company comes highly recommended, what you should look for is a well-established, reputable firm offering a good range of well-kept, up-to-date yachts. Shore facilities should include a maintenance shop, chase boat, and provisioning. Generally it is best to avoid the young, unknown companies that have but a few leased yachts docked in some rented slips.

While many sailors consider St. Thomas in the US Virgin Islands the best place to charter - largely due to its accessibility and provisioning opportunities - the BVIs are proving increasingly popular. Additionally, several yacht companies have recently transferred their headquarters from St. Thomas to the BVIs. ''Fully 75 percent of all Caribbean charters wind up in the British Virgins today,'' says broker Evelyn Whitney.

One of the largest and best known of the charter companies is the Moorings. A 16-year-old family-run company now working out of Tortola and St. Lucia, the Moorings offers more than 100 boats, two hotels, two restaurants, and a well-stocked maintenance shop.

Billing itself as ''the complete yachting resort,'' where most charterers avail themselves of the hotel facilities before and after their week on the water, the Moorings' repeat business is running about 65 percent, according to owner/operator Ginny Cary. Largely Gulfstars, Morgans, and some new Beneteaus, their fleet ranges in size from 39-footers to crewed 60-foot yachts. Depending on the size, prices for bareboating (renting the boat without a crew) start at less than $1,000 per week off-season up to $3,000 per week in high season. Be prepared to submit a ''sailing resume'' when applying for a bareboat.

Much smaller in scope than the Moorings is West Indies Yacht Charters, an 11 -year-old company located in Tortola's secluded Maya Cove. A BVI Bareboat Association member, WIYC offers 30 sloops in 31-, 39-, and 44-foot lengths. Rates run from $156 a day for their Allmand 31 off season to $344 a day for the Gulfstar 44 in season. WIYC also offers week-long cruising classes.

And for the optimum in comfort and safety - a consideration for first-time charterers with children - CSY (formerly Caribbean Sailing Yachts Ltd.) has designed and built its own fleet of sloops and ketches to be particularly dry, well-ventilated, and upright in the Caribbean seas. Highly popular seven or eight years ago, the CSY boats have since declined in desirability as more yachtsmen look for performance cruisers rather than stiff sailers. Additionally the age of the CSY yachts - up to seven years old in some cases - may also decrease their desirability. On the other hand, CSY offers hotel facilities, boats off the Honduras coast, and low rates - $630 a week off-season for a 33 -foot sloop.

Should all of this seem too intimidating - try a crewed charter either through one of the above companies or independent yacht broker. There are many to choose from and they tend to advertise in the back of boating magazines. Generally speaking, you will get a larger, more luxurious yacht via the brokers. Crewed charter rates start a bit higher - $2,600 a week for a new 44-foot yacht is common. But if you have a large party, boats can be had for less than $100 per day per person.

If, on the other hand, you have minimal sailing experience but would like to get some fast, go to the Offshore Sailing School located on Tortola. Started several years ago by professional sailor Steve Colgate, OSS is today one of the most extensive sailing schools in the world. Rates for OSS lessons in Tortola include classroom instruction, daily sailing, and hotel accommodations and range from $787 per week off season to $902 in season. Practical information:

For further information contact the British Virgin Islands Tourist Board, 370 Lexington Avenue, New York, N.Y. 10017. Telephone (212) 696-0400. Both the BVI Bareboat Association and Caribbean Charter Boat Association are reachable at PO Box 6571, Fort Lauderdale, Fla. 33316. Or contact the following charters directly through their US agents:

The Moorings, PO Box 50059, New Orleans, La. 70150, (800) 535-7289; West Indies Yacht Charters; 2190 SE 17th Street, Fort Lauderdale, Fla. 33316, (800) 327-2290; CSY, Box 491, Tenafly, N.J. 07670, (800) 631-1593; Off-Shore Sailing School, East Schofield Street, City Island, New York, N.Y. 10464, (800) 221-4326 .