How can we make warmer wetsuits?
The quick answer is make them thicker, but that’s not a very exciting thing to read on your Monday morning. In general, wetsuits keep you warm by trapping a thin layer of water near your skin. Rather than having to constantly transfer energy to the water in the ocean that happens to touch your skin, your heat goes to the smaller volume of water and heats it up better.
If this were the only thing a wetsuit did, just trapping water, then thickness would not matter. The neoprene, which has lots of air volume within the material, insulates the water/pee combo inside your suit from the ambient ocean water. Thicker wetsuits are better at this.
Most surfing wetsuits use closed-cell neoprene with a fabric lining. Open-cell suits (without lining) create a tighter seal against the skin and trap a thinner layer of water that moves less, increasing warmth relative to closed-cell suits. But if you’ve ever tried on an open-cell suit, you know why we don’t use it for surfing - it’s less durable and, since it suctions onto your skin, it requires you to lube yourself up like a slug to get it on fully. Diluted hair conditioner works pretty well
A research team at California State University San Marcos tackled the wetsuit warmth question from a different angle in 2020. They investigated whether the outer surface material – specifically slick (smooth) neoprene versus traditional jersey-lined neoprene – affects thermal properties.
In cahoots with Hurley, the researchers designed a 2mm experimental wetsuit with slick neoprene on the right half of the torso and traditional jersey neoprene on the left half. They recruited 79 surfers in total to test these suits, equipping them with skin temperature sensors at multiple points around the torso – chest and upper back in the first field experiment, abdomen and lower back in the second.
In the first field experiment, skin temperatures under the slick neoprene were significantly higher, with up to 1.5°C difference compared to jersey neoprene in the chest and upper back regions. The second field study showed similar results for the lower back (about 0.7°C warmer), though interestingly, abdominal temperatures showed no significant difference between materials.
To isolate the effects of sun exposure, they conducted a third experiment in a controlled indoor environment after sunset. Even without solar radiation, the slick neoprene still maintained higher skin temperatures in the chest and lower back areas, though the difference was less pronounced than in sunlight conditions.
All three of these trials also recorded perceived warmth. When asked which side felt warmer, 61.5% identified the slick side, while the remaining 38.5% perceived no difference. Not a single participant stood up for the jersey neoprene side.
The researchers proposed two mechanisms for slick neoprene's superior thermal performance. First, its embossed coating acts as a water repellent, preventing water from clinging to the outer surface, which reduces heat transfer from the body to the environment. Second, the shiny surface of slick neoprene more efficiently absorbs solar radiation, adding warmth through passive heating.
However, not directly examined in the study, another potential factor could be reduced evaporative cooling. Wind passing over a wet jersey surface might accelerate evaporation, which draws heat as water changes from liquid to gas – similar to how sweating cools us down. The slick surface, with its water-repellent properties, might minimize this effect, helping maintain warmth in windy conditions. I find myself approaching ice cube status significantly faster on windy days, and my guess is that evaporative cooling is a significant contributor to the slick coating’s warmth over traditional suits. This and the potential radiative heat reflection warrant a follow-up study.
This research suggests that strategic use of slick neoprene panels in chest and back areas could significantly enhance wetsuit warmth without increasing thickness. Despite manufacturers' durability concerns, I’d take looking more like a sea lion over an additional millimeter any day.
Further Reading:
I can't imagine a wetsuit rating done with Consumer Reports's sort of thoroughness. That item from Wetsuit Wearhouse comes across well. Cleanline's wetsuit guide is also useful. They've done a good job of getting webfeet into the surf.
Matuse's triathlon wetsuit (the Dojo 4.5/2.1/1.5 backzip with a slick neoprene exterior) seems to have been popular enough to stay in their lineup. It isn't suitable for use with a board, but works for swimming, provided you won't get beaten up by shorebreak. For me, it was good to get a slightly oddball XLS size. Tri brands seem to cater to taller, skinnier people.
Another issue might be wetsuit lining. XCEL straddles linings with Comp models that have thin, presumably slick lining for light weight and stretch, Drylock fuzzy fabric insulation for warmth. Matuse and Feral stick to thin, slick linings (I think Isurus and Buell, too). Feral's website explains their views. I was impressed by their 3/2 backzip, light, thin, easy to get in and out, non-leaky, and warm, so recently followed up with a 4/3/2. Feral's equal in the closet is a Hurley experiment. During the Nike era, they offered a wildly expensive made-in-Japan suit, thin-slick lining. I jumped on a sale price, then waited to lose enough weight for it to fit. This winter was wonderful. Hurley did experiments with surfwear: boardshort construction, thin wind-shielding "rash guards", underwear for wetsuits, and Nike technology. We've lost some of that. Vissla and little Hotline have pioneered easier-to-use chest entries. Seam bonding might possibly replace sewing? Combining stretchy neoprene with non-stretch stitches has long been a problem.
Damn good read.
As a person who's surfed the Pacific in a 3/2, I always questioned if there was a way to make warmer wetsuit without going much thicker like they use for the arctic waters (or double layering). Thicker or double layer just felt too restricting.
But after surfing Hawaii in boardshorts, it made me not want to go back to colder waters. 😂