Are you tormented by the question, ''Is this the summer I should have bought myself a 200-foot oceangoing motor yacht?''

I ask myself this question every time I sail out of the Belle Haven Marina here on the placid Potomac in my 19-foot rental Flying Scot and snag the centerboard in the muck of the ever-lengthening sand bar south of the Woodrow Wilson Bridge.

But my answer, which is also invariably the answer of my bank, is always a resounding ''No!''

These enormous, opulent tubs are certainly impressive (a 200-foot coal barge, I might add, is also impressive, especially when bearing down on you from the stern quarter), but they`re so damned boring, or as my friend Margaret the Smith Girl would say, simply too, too unamusing.

What you essentially do on them is sit around and drink-an inactivity that can be indulged in far more interestingly in any corner tavern on the Northwest Side of Chicago, without all that queasy bobbing up and down

(depending on how many shots-and-a-beer you`ve had to drink).

Arms mogul Adnan Khashoggi tried to make life more interesting aboard his 292-foot motor yacht Nabila by installing a sun deck acrawl with naked nymphets. But to frolic with the nymphets, you had to buy thousands of cases of AK-47s and white phosphorous grenades from him. I, for one, have all I need.

A cheaper way

In Cannes, you can sit around and drink in the thoughtfully provided lawn chairs overlooking the topless beach opposite the Hotel Majestic for absolutely nothing!-which is how I met my Parisian friend Marie-Gabrielle, and I certainly wouldn`t have wanted Adnan around for that.

Because life aboard these Truly Tasteless Tubs is so boring-and I`m told that even the gold-trimmed bidets aboard the Nabila are boring-that life aboard them is consquently also very lonely. People simply don`t want come aboard.

I know this fading Southern belle who with her never-present husband keeps a 145-yacht at the docks in Nice. But she spends her entire summer over there on the phone, desperately trying to get people to come and join her on

''The Boat.''

Like everyone else, I always beg off, usually pleading emergencies in the vegetable garden having to do with root-feeding mealybugs. She keeps at it anyway, and when truly desperate, attempts the ploy of the Famous Other Guest. Last year, it was Britain`s Queen Mother she ''invited.''

And did the Queen Mum come? ''Oh, yes. She had a jolly good time.''

Ha! At the Queen Mother`s age, Buckingham Palace is careful about allowing her rubber duckies in the bath, let alone permitting to step on anything that floats (and, consequently, sinks).

Steaming on empty

The Donald (as wife Ivana calls him) Trump bought the Nabila third-hand, changed the name to ''Trump Princess'' and, I think after consulting the Ivana, got rid of the nymphets. Now life aboard the yacht is so insufferably boring that not even Trump goes aboard. The tub just chugs about the seas aimlessly, without owners or passengers, like the Flying Dutchman.

And when you do manage to get people aboard your Truly Tasteless Tub, it can be even worse.

British media mogul (up from mere press lord) Robert Maxwell was in Washington recently for a Henry Kissinger symposium on China. When he apparently found no one was paying much attention to him (not to speak of Kissinger), Maxwell ordered his 185-foot-long (and I think 185-foot-high)

yacht Lady Ghislane brought down from New York. He hired a powerhouse PR company and, giving them 24 hours` notice, told them to round up as many Washington VIPs as possible for a big yachting party on the Potomac.

Kissinger didn`t show (at a yachting party just before, Maxwell had made all the guests take off their shoes, and one can`t imagine Henry even going swimming without his wing-tip $400 English walkers). But there are always those in the capital who respond when their string gets yanked, and the PR people managed to press-gang aboard the Ghislane such notables as CIA Director William Webster, British Ambassador Sir Antony Acland, historian Daniel Boorstin, National Gallery of Art Director J. Carter Brown, jillionaire heiress Pamela Harriman, columnist Georgie Anne Geyer and columnist and TV comic Robert Novak.

Enter the rabble

But they hardly filled the Ghislane`s poop deck, compelling the PR people to flesh out the assemblage with such less stellar types as former (not indicted for anything) Atty. Gen. Ed Meese, presidential-candidate-for-life Jesse Jackson and moi.

We were allowed to keep our shoes on. Otherwise, our big treat was being taken by Maxwell up to the top deck to see his Jacuzzi-or, if you will, his tub atop a tub-a marvel one can behold at any neighborhood health club.

We were given oysters on the half shell and giant shrimp so big I think they came from a Pacific atomic testing site, but mostly we just sat around and drank, enjoying a view that consisted mostly of a crummy motel across the harbor.

I`m told that the Donald now wants to sell his used Trump Princess and have a new, ''real quality'' yacht built in the 400-to-500-foot range (when you consider that New York yacht berthings are now going for $15,000 a foot, the Donald isn`t going to stay a billionaire long).

Perhaps he thinks he can just tie one end up in New York and the other in Atlantic City and simply walk to his casino from his condo.

Way to go

But he misses the point. Even in John Pierpont Morgan`s day, the purpose of a yacht was to have fun, to get out in the wind and spray, to go through the water in an interesting manner.

Witness consummate yachtsman Ted Turner, who won a deadly, storm-thrashed Fastnet Rock race some years back by lashing himself to the mast and sailing on, cursing the wind.

True yachtsmen would much rather be lashed to that mast with Turner than wandering carpeted decks oohing at the Donald`s bidets or ahhing at Maxwell`s tub.

I frequently find myself lashed to my mast and cursing.

Trying to get off this damned Woodrow Wilson Bridge sandbar. -