Gaskell lifted the prestigious Jack M Ogden Memorial Trophy with a 145 total, finishing three shots clear of Ilkley's Chris Atkins.
The Bedale man had led at halfway with an opening 73, which included birdies on three of the par-5s.
Atkins, who placed fourth in the recent Pannal Rose Bowl, was a shot back, while the host club's Glen Ient and Steve Whitwham (Rudding Park) both carded 75, the former with the aid of five birdies.
In the afternoon conditions deteriorated, persistent rain setting in for the remainder of the day, but scoring improved.
Knaresborough's Nathan Seal, the Union's junior captain, added a 74 to his morning's 76 to finish third.
Atkins repeated his first round of 74 to finish runner-up to Gaskell while Ient gained some consolation by winning the net prize with rounds of 72 and 73.