This article is from our April issue, themed “The Science of Surf.” Click here for more on our oceanic field studies, which include, but are not limited to, bathymetry, genealogy, hydrodynamics, wave pools, and stoke.
When it comes to surf equipment, the leash is usually an afterthought. To some it's a tangled, bothersome kook-cord, to others it's a lifesaver. Regardless of its pros and cons, the leash is 6 feet of cord trailing behind you, and it's essentially dead weight. Dead weight produces drag, making the leash the only piece of surf equipment not designed to improve performance on a wave. But just how much does a leash affect your surfing?
According to Aaron Perry, a yacht design engineer for ORACLE Racing (winners of the 2010 America's Cup), every surfer feels a different amount drag. "Drag goes up with the square of the speed, so the faster you go, the higher the drag," says Perry. "But a really rough estimate of assuming 15 mph of board-speed and a 5mm cord dragging, with 3 feet of effective length, gives you roughly 5 pounds of drag, which compared to the overall drag when paddling or riding is a small amount."
To get an idea of your leash's drag, Perry gives these instructions: "Test this by dragging your leash over the surface of a swimming pool with a spring scale attached. Or next time you come in from a surf, just Velcro the leash to the end of the board, push it around in the shallows, and see if you notice a difference."
Every surf leash manufacturer produces what we call "The Regular Leash"—some brands have even named models just that. It's the standard urethane 6-foot leash that averages around 5/16th of an inch thick. Sister to the "The Regular Leash" is the skinnier and slightly sexier comp leash. It's lighter and its dimensions are usually around 6 feet by 3/16th of an inch thick. Unsurprisingly, it's a popular choice among professional surfers.
Regardless of size and model differentials, some feel the leash is a burden and prefer to go without it. "I just find it annoying a lot of the time if the surf's not that big," says pro surfer and shaper Ryan Burch. "It's not necessary if you're surfing somewhere you're familiar with, and where you're hopefully not going to fall a lot."
However, when Burch is surfing bigger waves, he says he doesn't feel the leash lagging behind him. Bob Nealy, from Surf More XM who has been engineering new leash designs for over 35 years, believes this is true for most surfers and that the concerns of drag are overstated.
"If you take a look at a lot of the leashes when someone is flying on a wave, it's popping around on the surface of the water. The leash itself isn't even in the water," says Nealy. "It's only on the takeoff that the leash is down in the water."
World Tour veteran and longtime test pilot for OAM leashes, Taylor Knox, personally believes leashes don't interfere with his surfing. "I’ve never thought about how a leash could be holding me back," says Knox. "I think a big leash with a little bit of drag isn't a bad thing—it could put you deeper in the barrel."
While that may be true for someone of Knox's caliber, the recreational surfer will probably see it differently. But Knox also points out that there are other, less tangible affects of wearing a leash.
"Not wearing a leash is mental freedom more than anything else, and for a lot of people it's also a mental block, because they're not worried about falling," he reasons.
In spite of the cons of drag and the pros of it being attached to your board, Nealy believes a happy medium is the comp leash. "I almost always use a comp. Using a regular or big-wave thickness cord I think is warranted if you're surfing really big days or are in Hawaii or something," says Nealy. "But for the average everyday good surfer, and someone using a board under 7', I'd recommend using a 6-foot comp leash."
The reality, it seems, is that the amount of drag caused by a leash does not outweigh the convenience of being attached to your board. And while boards, fins, and wetsuits continue to reach new performance heights, the leash, after 41 years of slow evolution, is still a work in progress.