Arthur Frayler led much of the way in Friday's 2012 Open Water National Championship 10K before a late mistake and a late charge by winner Andrew Gemmell, of Wilmington, sunk the Germantown Academy senior.

Frayler, 18, who will be attending the University of Florida in the fall, brushed against a buoy in the next-to-last lap around Miromar Lake, near Fort Myers, Fla. It disrupted his rhythm and allowed a hard-charging Gemmell to surge ahead and capture the event.

Gemmell, 20, a Maryland native who trains in Delaware, completed the grueling event in 1 hour, 58 minutes, 3.87 seconds. Frayler, the runner-up in the 10K at last summer's Pan-Am Games, finished fifth (1:58:19.67).

While Frayler failed to earn an Olympic berth this year - the U.S. men's representative will be Alex Meyer, of Ithaca, N.Y., who finished 10th on Friday but earned the honor thanks to a fourth-place finish at last summer's World Championships in China - he likely guaranteed himself a spot on the 2013 national team.

Gemmell's victorious surge came just before the last of six laps around the lake course. He crossed the finish nearly 12 seconds ahead of runner-up Janardan Burns of Mission Viejo, Calif.

In the women's 10K, Ashley Twitchell of Fayetteville, N.Y., won with a time of 2:03:06.03. Haley Anderson of Granite Bay, Calif., was second (2:03.50.44). Both women will have an opportunity to qualify for an Olympic spot at a June 9 race in Portugal.

Contact Frank Fitzpatrick at 215-854-5068, ffitzpatrick@phillynews.com, or @philafitz on Twitter. Read his blog, Giving 'Em Fitz, at www.philly.com/fitz.