MARTHA'S VINEYARD - My good friend Prof. Heinrich Applebaum has just done a sociological study on how private beaches affect the average American's vacation. He did it under a grant from the Life Is Unfair F11916tion.

Applebaum's study came to soem startling conclusions.

"You would think," he told me, "that people who own their own beaches would be twice as happy as those who don't."

"That certainly figures," I said.

"Well, it's not true. My interviews indicate that those who had no rights to a private beach are 3 1/2 time happier than those who do."

I was certainly surprised.

He said, "It appears that those who don't own beach-front property believe the ocean is public and they have the right to use any beach they want to, whether it's marked 'PRIVATE' or not. In fact they prefer to use a private beaches nicer, but it drives the owners up the wall."

"I should think so. A person with a private beach has paid through the nose for it and he doesn't want just anybody using it. There are still such things as property rights in this country."

"Public bathers don't believe this," Applebaum said. "They feel that a beach is a beach is a beach, and if they can get away with using a private beach rather than a public one, their day is made. This is particularly true of nude bathers, who will walk miles across dunes, sand and rocks to camp on a piece of property that is off limits to them."

"That's terrible."

"It's worse than that. I discovered in my studies that as the summer goes by the owners of private beaches start suffering sevese mental problems, including depression, paranoia and hysteria. Very few of them can cope with strangers using their beaches. At the end of the summer they are psychological wrecks."

How so?" I asked.

"Well, they get up in the morning and the first thing they do is go down to their beaches to see if anyone is on it. The thing about private beaches is people use them not only for sunbathing in the daytime, but also at night for other things. If they find their beach has been used at night it drives owners crazy. "Get off my beach!" they scream at the people wrapped intheir blankets.

"Then the beach owners go back to their houses to have breakfast. After breakfast they go back to the beach to see who is on it. If no one has arrived yet, they go into town to buy the papers and shop for groceries. But they are very ill at ease because all the time they're away they keep wondering if anyone is on their sand.

"When they return from town they immediately go back to the beach to check it out. They sit on a sand dune waiting for the invaders. Some people send their children down to stand guard, and at th first sign of an unauthorized bather, the children sound the alarm and everyone goes down to the beach to drive the trespassers off. It th sunbathers refuse to move, they have to go back to the house to call the police. This can kill two or three hours.

"It doesn't sound like much fun for the beach owners," I said.

"It isn't. They can't accept lunch dtes, or go fishing or sailing because they believe as soon as they go someone will walk on their property."

"A perosn could develop a complex after awhile."

Most of them do," Applebaum said. "They have nightmare hallucinations, and crying jags. They start talking to themselves and, in some cases, they even plot murder. If these people don't get treatment they can become a danger to society."

"Then on the basis of your study you're recommending that people who own waterfront property seek pyschiatric help as soon as the summer is over."

"It's essential." Applebaum said. "A person who owns a parivate beach at a summer resort is a walking time bomb that could go offf at any moment."