



A short decade ago, the term “volume” meant just about nothing to the average surfer. We knew that the length, width, and thickness of our boards mattered—three measurements that actually combine to create volume—but litres weren’t something that we ever discussed.

Maybe we were too fixated on waves to care how much foam we were toting around; maybe we just needed someone famous to tell us that it was important.

Taj's Guild Factor? 0.35 © 2020 - WSL / Cestari

Whatever the case, it has only been in the past 5 or 10 years that we’ve started to pay attention to volume, and for many of us it is still something that’s almost frightening and esoteric—a concept that we know is important, but that we only pretend to understand.

Fortunately, there are a few scientific-minded surfers out there who are happy to do our thinking for us, and I just happened to stumble across one of them last week in Moab, Utah, of all places. Deserts seem to attract a strange crowd, with all sorts of riff raff attracted to the expansive freedom they afford, and apparently that riff raff includes wave-riding scientists who come up with elegantly simple formulae to explain the intricacies of surfboard design.

A short conversation about mountain bike trail info quickly turned to other passions, which naturally led to talking story about surfing, and before I realized what was happening I’d spent an hour talking litres.

Whitney Guild isn’t your typical Utah desert rat. He’s been surfing and competing for over half a century, was a team rider for Greg Noll, Bing, and Jacobs Surfboards, towed Jaws at the age of 50, and has a plaque on the Surfer’s Walk of Fame in Hermosa Beach, CA.

The man behind the formula, Whitney Guild.

He now splits his time between homes in Southern California and Northern Baja, and apparently sneaks off to Utah whenever he feels like mountain biking slick rock or setting hang gliding altitude records. A scientist both at heart and by profession (he has a degree in meteorology), Guild has always understood the importance of volume to the surfboard design conversation, but as litres became a popular topic of discussion over the past decade, he decided someone ought to come up with an easy-to-understand explanation of the concept. The result was the Guild Factor.

The Guild Factor is actually incredibly simple. It is the ratio achieved by dividing the volume of a surfboard (in cubic litres of foam) by the rider’s weight (in kilograms). As an example, a surfer who weighs 90 kg and rides a board that is 45 litres would have a guild factor of 0.5. This ratio can then be used in the opposite direction to help people customize their boards.

So if you’ve recently seen your six-pack turn into a beer gut, but know that your magic paddle-to-performance ratio on a shortboard is a Guild Factor of 0.40, you simply multiply your weight (in kg) by that number, and that will give you the volume of foam in litres that your shaper should put into your next shredstick. Simple, right?

The displacement tank Whitney used to refine and validate his formula.

The elegance of Guild’s equation didn’t fully really reveal itself until he started field testing the concept. Over the years, Guild compiled information from just about every surfer he could get his hooks into.

Then, in 2016 he attended the world tour event at Trestles and the final qualifying series event at Sunset, where he polled dozens of pro surfers about their weight and the volume of their shortboards—and he was amazed by what he found. As it turned out, virtually all of the pros he interviewed were on boards with Guild Factors between 0.34 and 0.36, with the vast majority riding exactly 0.35.

These were athlete’s who had worked with their individual shapers for years and sometimes even decades to dial in the feel of their ideal boards, and yet somehow they had all achieved virtually the exact same ratios between weight and volume. And this wasn’t exclusive to pro surfers, either. Although their numbers were a bit higher, everyday surfers seemed to congregate consistently around specific Guild Factors as well, depending on their ability and fitness. surfers with a high fitness level were in the 0.36-0.38 range, weekend warriors hovered somewhere between 0.38 and 0.42, and novices or surfers in extremely small waves and thick wetsuits tended to range between 0.40 and 0.50 Guild knew he was onto something, and decided to take his concept public. At the same time, he sorted through the years’ worth of data to create a general scale for potential board buyers. In general, pros are riding shortboards with a Guild Factor of 0.35, average to above-average surfers with a high fitness level were in the 0.36-0.38 range, weekend warriors hovered somewhere between 0.38 and 0.42, and novices or surfers in extremely small waves and thick wetsuits tended to range between 0.40 and 0.50.

Longboards and SUPs were a bit more difficult to nail down, as there are less boards in circulation and their volumes tend to vary widely. But Guild has developed a sliding scale for them as well Standard longboards feature a Guild Factor of 1.0, with high performance longboards a bit lower at 0.90. And SUPs range from GF 2.0 for beginners to 1.3 for advanced riders.

As the importance of volume became firmly established throughout the surf industry, it was only a matter of time before big-name board builders jumped on Guild’s bandwagon. SUPER, Arakawa, Roberts, …Lost, and Visionary Surboards in the UK have all adopted the Guild Factor to help customers with the board-ordering process, and Matt Biolos of …Lost has even posted the info from his own personal boards, as well as those of his team riders, online to serve as a guide. (Biolos rides a Guild Factor of 0.42, while Kolohe Andino, Taj Burrow, and Brett Simpson are all at 0.35, and Mason Ho is at 0.37.)

The Guild Factor's been used by Lost shaper Matt Biolos - going some way to helping tweak magic whips for the likes of Kolohe Andino. © 2020 - WSL

But although his equation has already been tested, proven, and adopted by top board designers, Guild isn’t content to rest on his laurels. He is actively advocating the concept, and is currently in licensing discussions with a number of other major surfboard brands.

And on a personal level, he enthusiastically shares his discovery with surfers everywhere he goes—even in places as random as the the Moab desert.

So the next time you are ordering a board and aren’t sure what volume you need, give Guild’s formula a spin. And if you happen to find yourself a thousand miles from the coast and see someone who has that trademark surfy look to them—leathery skin, wrinkled eyes, faded North Shore trucker hat—go ahead and strike up a conversation. There’s no telling what you might learn.

And if you want to help Whitney Guild collect more info on surfer volume then head this way to add in your whip's details to his blog.