Santa Cruz resident Sam Shimomura swam the fastest time of anyone at the 39th annual Rough Water Swim — a one-mile swim around the Santa Cruz Municipal Wharf — and took the junior and masters titles on Saturday, according to preliminary results on bigskyendurancesports.com.

The 18-year-old arrived at the finish line on Cowell Beach in 17 minutes, 16.30 seconds — 15 seconds ahead of runner-up Trevor Gillis [Los Altos-Mountain View] in the masters division and almost two minutes ahead of runner-up Caleb Cripe [unattached] in the junior division. Cripe, 13, crossed the finish line in 19:28.20.

Sandy MacDonald [Sierra Marlins Swim Team] was third in the master men’s race in 18:38.15, and Jonah Silva [unattached] was third in the junior boys race in 20:58.15.

Slug swimmer Janey Heyman, 16, was the junior girls winner, crossing the finish line in 21:00.20. She was followed by runner-up Maddie Stander of Seaside, who finished in 21:10.56, and third-place finisher Mary Welton [Valejo Aquatic Club], who finished in 21:13.45.

Stanford’s Susan Preston, 50, won the masters women’s race in 17:50.50. She was followed by Lynn Jolly [The Olympic Club] in 20:58.30 for second place and Stephanie Rebro [UNAT] in 21:09.85.

In the wetsuit divisions, Margaurite Meyers [TOC] won the women’s race in 20:18.65 and Matthew Benoit [TOC] won the men’s race in 18:35.45.