Patrick Kennedy of North Baltimore Aquatic Club and Patty Gavin of West Chester (Pa.) Swim Club each captured three gold medals yesterday to dominate the senior men's and women's divisions in the opening session of the second annual Olympian Invitational Long Course Swim Meet at Starlit Aquatic Club in Fairfax.

The meet concludes today with the senior finals beginning at 9 a.m. The age group finals begin at 12:30.

Kennedy, 17-year-old senior at Loyola High School in Towson, Md., who placed fourth nationally in the senior 200-meter backstroke in March, won easily in the 200-meter butterfly, 100-meter backstroke and 200-meter individual medley. His time of 1:00.73 in the 100-meter backstroke qualified him for this summer's junior nationals.

Gavin, who led her club to the girls Mid-Atlantic championship in March, swept the 200-meter butterfly, 200-meter freestyle and 200-meter individual medley. After destroying her challengers by nearly 10 seconds in the butterfly, she edged Starlit's Jenny Rapp in the freestyle and medley. Seven-hundreths of a second separated the two in the medley race, which Gavin won with a quick touch at the wall.

"She (Gavin) is a dynamite swimmer," said Starlit Assistant Coach Ron Haje. "She has a lot of potential." He also praised Rapp, his top female swimmer. "Jenny has received a scholarship from Stanford. I'm sure she'll really blossom in college. She will be one of the tops."

The Potomac Valley Swimming Committee, once a branch of the Amateur Athletic Union, sanctioned the meet whichg attracted 23 clubs from as far away as Connecticut and New York. But in the girls division, 21 teams could have stayed home. The top three finishers for the day's five girls events were either from Starlit or West Chester.

The girls 100-meter breaststroke was won by Susan Rapp, Jenny's sister. Susan, who owns the Potomac Valley record in the event, blazed to a four-second victory over Susan Bier.