SAY, BUDDY, how much does this baby go for?"

Those nine words are the quickest way to disgrace and humiliation at the 16th annual United States Sailboat Show, which opens to the public Friday on Annapolis City Dock.

This show, which features 600 yachts up to 85 feet jammed into a space that normally accommodates about 30 boats half that size, has grown so popular, some companies have taken to hiring "hostesses" to weed out deadbeats, so the exalted salesmen can concentrate on potential buyers only.

"What the hostess does is conduct a 'first qualification' interview," said a boat show veteran. "She greets you as you come aboard and asks a few questions. If she doesn't like what she sees, it's 'Step through this door, please.' Then, splash!"

The U.S. Sailboat Show was the nation's first in-the-water boat show and took off like a fall brush fire. There are imitations everywhere now, but Annapolis remains the industry's No. 1 gathering place each October.

This year it costs $7 for an adult to get a glimpse of the myriad boats and equipment assembled in one of Maryland's most scenic spots. If paying $7 to get into a showroom offends you, how are you going to feel when a hostess refuses to let you see the salesman?

Some keys to getting the respect you clearly deserve:

*Do not, repeat not, wear new deck shoes to the show. New deck shoes are the surest sign of a duffer, along with those captain's hats with the scrambled eggs.

Real sailors wear deck shoes with holes or, better still, no shoes at all.

*Do carry or wear foul-weather gear at all times, regardless of conditions. All proper sailors know a storm's over every horizon.

*Never ask how much anything costs. As old J.P. Morgan said, if you need to ask, you can't afford it.

*Be scruffy. Scruffiness is next to godliness among serious sailors. Tattered jeans are a must, tight enough that the hostess can see the bulge of your overstuffed wallet. Once a visitor to the show considered giving some spare change to a barefoot fellow in threadbare jeans who was washing down a display boat, only to find out it was Warren Luhrs, president of Hunter Yachts, who later won the singlehanded OSTAR trans-Atlantic race in Tuesday's Child, the boat he was washing.

*Study terminology, and use it shamelessly. How do you think Howard Cosell got rich?

The show is issuing 8,500 working passes this year, which means roughly the population of Bennington, Vt., will be on duty. Most of these passes are for salesmen, who wear nice blue blazers but may know nothing about boats.

Make a quick inspection, then say something like, "These turning blocks for the running backstays, are they through-bolted with a backing plate' Or, "How do you remove the babystay for jibbing the spinnaker?"

Questions like that ought to win you an interview with the president of the company.

*Get there early. The show opens at 10 a.m. Friday through Monday. By lunchtime it's packed and you're just a face in the crowd.

*Do not inspect giant boats like the 85- foot Pilot Marine, which has six staterooms, six heads with showers and a Porsche on the fantail, and expect to be treated like anything but the penniless cur you are.

*Do inspect sailboats in the 25- range, where the market has been soft for about a year and where the salesmen will be anxious enough to be civil, at least briefly.

One question that sales personnel always ask once a dialogue has begun at the boat show is, "What type of boat do you own now?" You must be prepared for this question, and have your response ready.

I'd tell you to say, "None right now, I've been so busy with the jets." But that's my line. ROUND ABOUT BOATS

Parking is practically impossible in Annapolis during the sailboat show and the subsequent power boat show, which runs the following weekend at the same site. Show organizers recommend parking at the Navy Stadium parking lot on Rowe Boulevard, which is the main road into Annapolis off U.S. 50, and taking the shuttle bus downtown.

Annapolis is a walking town, anyway, with restaurants, shops, the State House, marinas, cobblestone streets and 18th-century houses scattered around downtown to explore when you tire of gleaming, overpriced yachts.

Don't ask anyone for directions. Many native Annapolitans leave town at boat show time to make room for an estimated 50,000 to 100,000 yachting-oriented visitors, and the ones who stay shun downtown.

U.S. SAILBOAT SHOW -- Friday through Sunday, 10 to 7; Monday, 10 to 6. Admission is $7 for adults, $3 for children under 12.

U.S. POWERBOAT SHOW -- With 350 motorboats on display, runs Thursday through October 12, 10 to 7; October 13, 10 to 6. Admission is $6 for adults, $3 for children under 12.