Every summer, Burke Pieper Jr. crosses his fingers when he rents out his two-bedroom apartment in Ocean City. He's found that renting the vacation condominium can bring surprises and headaches along with extra income.

One summer, for instance, he discovered 12 people crammed into the apartment, which he had rented to four people.

Every spring, Marina Chaconas said she spends about $700 to clean rugs soiled by sand and saltwater and to repaint fingerprint-stained walls.

Pieper and Chaconas are among the hundreds of property owners along the Delmarva shore from Ocean City to Rehoboth who rent their apartments, cottages and homes to vacationers who come from the District, Baltimore, northern Virginia and elsewhere for weeks at a time.

Owners say they rent the properties to take advantage of tax benefits and to earn extra money. But with the advantages come all sorts of risks.

"The quality of person has deteriorated," said Pieper, a Baltimore watchmaker who has owned and rented apartments in Ocean City for the past 11 years. "People don't have as much respect for property as they used to. In general, when people are renting from you they don't take as good care of it as you would. Over the course of the years I've had some really, really bad experiences."

Most owners turn their property over to a real estate agent who rents the apartment, house or cottage on a weekly basis. Rents are usually set at the beginning of each season, which traditionally lasts from May to September, and run from $350 a week for a two-bedroom oceanview apartment to $1,200 a week for a two-bedroom townhouse.

Many owners and rental agents said the rental season is getting longer. It traditionally has been eight to 10 weeks a year, but some said they have places booked for as long as 17 to 20 weeks.

Rentals facing the ocean are more expensive than those facing inland bays, and rents tend to be $25 to $75 higher during the peak season between the middle of July and the end of August. Other rentals are located on what Ocean City residents call "ocean block," which means they don't have water views but are on blocks near the ocean.

The rentals range from houses and mom-and-pop motels to high-rise condominiums.

Each year rents rise 5 to 10 percent along the Eastern Shore, owners and rental agents said. A typical rental is equipped with beds, living room furniture, a kitchen, cooking utensils and a washer and dryer. The renter has to provide linens, towels, paper goods and food.

If the rental is listed with an agent, the owner has to pay a commission of as much as 16 percent of the weekly rent. Even if owners rent the properties on their own, they have to pay for insurance, as well as a $100 annual license fee and a $100 noise permit fee.

Many owners bought vacation homes to take advantage of write-offs available under the tax laws that existed at the time. In the past, owners of rental property have been allowed to use real estate losses from depreciation and expenses to reduce their taxes on income from other sources, such as salaries or professional earnings.

However, the tax changes made last year severely restrict deductions of some real estate losses against other income. People who earn less than $100,000 a year and are active in the management of their rental property can deduct up to $25,000 in losses from those propertiesagainst their other income; those with incomes up to $150,000 can deduct less than that, and those with income of more than $150,000 are not entitled to deduct any such losses from other income.

Whatever the benefits, it is clear that owning rental property can entail plenty of work.

Pieper said he does all of the painting, carpeting and other repair work on his property. Each year he tries to improve the apartment in some way, he said, and spends quite a few weekends working on the apartment. Aside from damage caused by the tenants, the salt air causes problems with paint and furniture, and sand ruins the carpet.

Chaconas, a real estate agent with Moore, Warfield & Glick Inc. Realtors in Ocean City, bought a two-bedroom, two-bath oceanview condominium in English Towers and lived there for 10 years before moving into a single-family home and renting the condo. She said that since she starting renting it out two years ago, she has spent as much as $700 a year to clean and repair the condo.

"The nicer the place, the better they take care of it," she said. "If there are spots on the rug, if a person spills something on it, they'll be less inclined to clean it up."

Chaconas said she has found renting a profitable venture despite the maintenance costs. Last year she rented it for 13 weeks and grossed $7,600; she said she expects to gross about $8,500 this year. At the same time, the value of the condo has jumped from $43,900 in 1975 to about $142,000 this year, she said.

But J. Joseph Tansey, owner of Tansey-Warner Inc., a real estate firm in Bethany Beach, Del., said that any owner who considers renting must be prepared to take some losses.

"No matter how much you rent it and with all the expenses, there tends to be a negative cash flow," he said. "You have to make sure you can carry it."

Donald K. Rose, author of "The Vacation-Condo Game," a 124-page guide that provides tips to owners renting their property, said owners should carefully review their finances, particularly the monthly statements from their rental agents, to make sure their time and money is worth the effort. Commissions to rental agents, repair costs and permit fees tend to add up, and the properties will probably be vacant during the late fall and winter.

Chaconas and other owners say they ask their rental agents to be selective. Some do not like renting to teenagers -- particularly in June, when many high school graduates spend a week at the beach. Other owners said they prefer renting to families, who tend to take care of property a bit better.

"Anybody spending $800, $900 or $1,000 a month on place isn't likely to trash it," Tansey said.

"You have to be very careful," Pieper said. "Just don't do it for the money."

@Beachfront property at 118th Street in Ocean City. @The Heron House Condominiums on the sound at 120th Street in Ocean City.