“What’s the water temp”? will be asked in a dozen different accents as you stand at the edge of any British reservoir at seven in the morning before a triathlon. The fog will still be low and the surface will be gray and unaltered. It’s not casual conversation. The response determines what each competitor is permitted by law to wear into the water; making a mistake during registration is a one-time occurrence.
People get confused just by the terminology. Swimskins, skins wetsuits are not synonymous terms for slightly different versions of the same thing. In terms of racial regulations, they fall into different legal categories the distinction is much more significant than most novices realize.
Swimming in your trisuit that stylish one-piece you’ll also wear for running and cycling is what it means to race in skins. For pool triathlons and open water events where the water temperature has risen to the point where wearing a wetsuit is prohibited, this is the standard.
There’s nothing wrong with it, but you’re basically exposed to the water in the most basic sense because it doesn’t provide any buoyancy or drag advantage. This is how some athletes excel at swimming. Others find the open water unexpectedly humbling without the extra float, especially those who train indoors most of the time.
The equation is significantly altered by a suitable triathlon wetsuit. It is made of smoothskin neoprene and raises the hips and legs into a more horizontal position, which at first seems almost unfairly beneficial. Many swimsuits, particularly those who are just starting out, naturally sink at the lower body, which requires the arms and shoulders to compensate and uses energy that could be saved for the bike. The swim leg feels more like racing than survival when wearing a good wetsuit.
The temperature thresholds are quite precise according to British Triathlon Federation regulations. Wetsuits are prohibited for swimsuits 59 years of age and younger when the water temperature reaches 22°C for swims up to 1,500 meters or 24.6°C for longer swims.
When the temperature falls to 15.9°C or lower, wearing a wetsuit is no longer an option but a safety necessity. Due to the reasonable recognition that cold water affects people differently at different stages of life, older age groupers are granted a slightly more generous permitted range across all distances.
You may occasionally see professionals race without wetsuits on a morning when everyone in the age-group field is still zipped in. This is because elite and younger competitive categories operate under stricter limits, prohibiting shorter swims at 20°C. It may appear strange. It’s completely intentional.
The swimskin, on the other hand, occupies an intriguing middle position. Since it doesn’t add buoyancy or neoprene, it can be used in swims that are officially non-wetsuit. With flat seams, a rear zip that removes in a matter of seconds during transition a compressive, water-repellent layer that sheds water instead of absorbing it, it does provide drag reduction.
The swimsuit makes sense for a 3.8-kilometer swim in warm water where wearing a wetsuit is prohibited and you’re looking for any legal advantage. It’s important to note that most major governing bodies, such as IRONMAN and British Triathlon, also forbid neoprene accessories like wetsuit shorts or neoprene kneeskins when a race is declared non-wetsuit. The only extra layer allowed is a swimsuit composed of textile-based material.
In the UK, spring racing is in extremely uncomfortable territory. The temperature of the air rises. Lakes and rivers warm more slowly than water a windy morning can make 16°C feel more intense than any reading on paper would indicate.
While the water is well below the ban thresholds, the wetsuit continues to be the sensible solution for the majority of the early season. The swimskin starts to earn its locker space by July and August when that computation starts to change.
Regardless of what general rules recommend, it’s worth consulting the athlete guide for your particular race. British Triathlon and Ironman don’t always agree on the finer points; Norseman, being the obvious extreme, operates under completely different conditions. Although the rules are not always the same, they are also not arbitrary.
i) https://zone3.com/blogs/inside-zone3/swimming-in-skins-vs-wetsuits-vs-swimskins-what-triathletes-need-to-know
ii) https://www.220triathlon.com/training/swim-training/will-water-temperature-affect-your-triathlon-race-day-swim