Equipment and Gear
The equipment allowed in a race depends on the sanctioning body and/or the race organizers. For example, races may have divisions for wetsuits and/or relays; may require escort boats / kayakers / paddleboards; and may require specifically colored swim caps. Some swimmers tend to keep it simple, using a basic swimsuit, goggles, and swim cap. Many records are based on that attire, which is known as 'channel attire' because it is stipulated in the rules for English Channel crossings and the rules for other long swims.
For triathlons, competitive rule 4.4 of USA Triathlon, states that "each age group participant shall be permitted to wear a wet suit without penalty in any event sanctioned by USA Triathlon up to and including a water temperature of 78 degrees Fahrenheit (26 °C)." The ITU rule is that wetsuits are allowed for elite triathlons at below 23 °C (73 °F) if 3,000 metres (9,800 ft) or more, and below 21 °C (70 °F) if shorter. Wetsuits are mandatory in triathlons below 16 °C (61 °F) if 3,000 metres (9,800 ft) or more.
Various types of wetsuits of varying thicknesses are used in open water swimming. Some employ high-tech materials and workmanship, others are of basic materials found in surfing and diving wetsuits. Some designs cover the torso, arms and legs, while other designs leave the arms and shoulders exposed.
When a person floats motionless in the water, their legs tend to sink. When a person swims freestyle, the legs rise toward surface because water passing underneath the body pushes the legs up, similar to how the wind can lift a kite into the air. In addition, a proper kicking technique will bring the legs all the way to the surface, creating a more streamlined profile for the arms to pull through the water. Both of these mechanisms of becoming horizontal require a small amount of energy from the swimmer. When a person wearing a thick wetsuit floats motionless in the water, their legs tend to float on the surface. Theoretically, this obviates the small energy expenditure mentioned above, although an additional small amount of energy is required to continually flex the wetsuit during swimming motions.
High-end triathlon wetsuits have extra flexibility that provides easier range of motion than a surfing or diving wetsuit. Some triathlon wetsuits have varied thickness by way of panels that provide custom flotation that aids the wearer in keeping an efficient position in the water.