As an onshore breeze fell short of forecasts at only 6 to 10 knots, Paine was doing the math.
Everyone thought Douglas had thrown out his opening ninth place that resulted from failing to round the windward offset mark, but Paine, trailing by two points entering the last day, brought it back into play by forcing a worse finish in the next-to-last race.
"If I made him count his ninth it would change everything," Paine said. "So I raced him to the back of the fleet."
When Douglas tried to escape, Paine was able to stay in control, as the rest of the fleet sailed its own race. Although Douglas eventually passed Paine, the tactics resulted in Douglas finishing 13th, third from last, to Paine's 14th in the penultimate race.
But it was delicate strategy. In the last race Paine placed fourth to Douglas' seventh, which left the latter with 23 points, only one ahead of Sprague, while Paine discarded his 14th for a final tally of 16.
Now the top pair, each 23 years of age, will continue training together into the World Championships at Santander, Spain in September. No hard feelings?
"We've been sailing against each other since we were kids," Paine said. "It's a lasting friendship."
Douglas added "Let's just say we both plan to go to the  Olympics."
Paine, a member of San Francisco's St. Francis YC, currently is sixth in the ISAF Sailing World Rankings for the Finn class whilst Douglas, of the Royal Canadian YC in Toronto is #21. The North American's is graded by ISAF as a 100 point regatta with the next release of the ISAF World Rankings is on 2 June 2014
This was Paine's first Finn North American title. Douglas won it two years ago.
The result also was meaningful for Sprague, who at 68 is old enough to be their grandfather but still going strong. "It's been a good year," he said. "I won the Zellerbach Regatta at San Francisco this year. I also won it in 1964---50 years ago."
Final Results - Top 5
1. Caleb Paine (USA) 16pts
2. Greg Douglas (CAN) 23
3. Henry Sprague (USA) 26
4. Erik Lidecis (USA) 27
5. Philip Toth (USA) 32