Together they enlisted the help of nutritionist Nikki Hart and researchers from the University of Otago to create a solution.
They were able to tap into $45,000 of government funding for research and development, matched dollar-for-dollar by the founders and two early-stage private investors.
Flyhidrate was born.
Consisting of three different drinks, it aims to address the issues that arise at various stages of long distance flights.
"We couldn't achieve what we wanted to do in one drink and that was to deliver the specific ingredients the body needs at the right stage of the flight," says Spratley.
The goal is to fight the main physiological stresses of flying: poor circulation, radiation exposure and dehydration, he says.
The brightly coloured beverage line-up includes a take-off brew containing relaxants, an in-flight drink with digestion assisters and a landing pick-me-up containing caffeine.
All three beverages contain electrolytes for hydration, circulation assisters and antioxidant boosters.
"There is a rationale for the three drinks, and they are three different formulations; they're not just three different colours," Spratley says.
One of the biggest challenges was getting the blends to taste right. "Most of nature's useful compounds are bitter and astringent and if you're going to make a truly functional beverage that can work in this sort of time space it's very hard to come up with a beverage that's pleasant tasting, so we had to overcome that and I think we have."
After the research, including flight, altitude chamber, blood and plasma tests, plus trials on aircraft acceptability and flavour profiling with the public, Flyhidrate had a trial run in Relay stores at Auckland airport last April.
At the end of 90 days Relay decided to stock the drinks in its two Auckland airport stores and is introducing Flyhidrate into Relay shops in Wellington, Christchurch and Queenstown airports as well as the major Australian airports.
It's not a cheap tipple: the long-haul version costs $18.99 and the short-haul variety, which would suit a hop across the Tasman or a trip to the Pacific islands, is $15.99.
Spratley says the premium price results from not skimping on anything, with two of the ingredients costing more than $7000 a kg.
Since they began developing the product more than three years ago several competitors have appeared, including New Zealand-based in-flight drink 1Above.
Spratley believes Flyhidrate has the most advanced formula.
The next stage of development is a new brew to help broaden the market, which restricts the sale of Flyhidrate to the post-customs side of the airport.
The new version also makes it possible to continue to use the product on multi-leg flights, circumventing liquid security issues that can occur when transiting, and which vary from airport to airport.
Flyhidrate has attracted a loyal following from international sportspeople.
Money can't buy the sort of publicity that comes from the likes of Piri Weepu telling his 70,000 Twitter followers he's about to slug some Flyhidrate on an international flight.
The combination of an efficient vascular system and sports-related trauma to muscles and veins put elite athletes at a higher risk of developing DVT, creating a market for the product that wasn't envisaged when Flyhidrate was conceived.
The company has been approached by a number of rugby teams, with players in the All Blacks, Crusaders and South Africa's Sharks trying out the drink on long flights.
An appearance at a catering industry show in Abu Dhabi has also resulted in interest from Etihad and Emirates airlines.
Ultimately the company would like to form a partnership with a global drinks player to boost international growth, says Spratley.
"It would be a real goal for us to crack the airlines and have them as partners.
"But I suppose the Holy Grail for us would be to get on the radar scope of a large beverage brand that can take this forward a lot faster than we could do without them."
