[2][3] Koh trained throughout his sporting career at SAF Yachting Club in Changi, under the tutelage of his personal coach Brett Beyer, a six-time Laser Apprentice Master world champion from Australia.

There, he and his partner Tan Wearn Haw finished twenty-eighth in the men's 470 class with a net grade of 192, sparing them from the back of the fleet by a twelve-point edge over the Hungarian duo of Marcell Goszleth and Ádám Szőrényi.

[5] Switching to a single-handed dinghy, Koh sought to bid in the open Laser for Athens 2004, but he lost the selection to two-time Olympian Stanley Tan.

He finished twenty-third out of 52 sailors in the silver fleet to lock one of the ten quota places available at the Worlds six months earlier in Terrigal, New South Wales.

[6][7] Koh stayed in the middle of the fleet throughout the series, until he chased harder to finish third on the penultimate leg by a few marks ahead of Poland's Maciej Grabowski.