How Do Wetsuits Work

Wetsuits were designed to keep water sports athletes warm in cold waters. They opened the door to winter water activities, and have helped athletes to perform in less than favorable conditions.

But how do these black, tight-fitting suits actually work, and keep you warm?

Fit

First and foremost a wetsuit should be comfortable. But at the same time, it should be tight-fitting and gently apply pressure squeeze across all of your body. Once in the water, a small amount is absorbed by the wetsuit, and the water then sits between the material and your body, held in place by the pressure applied by the wetsuit.

A loose wetsuit would result in too much water entering, and not being held in place.

The warming effect of a wetsuit is not instantaneous. So at first, you will feel cold whether in a tight or loose-fitting one.

In a tight-fitting wetsuit, a thin layer of cold water moves into the suit material and is warmed by your body heat. A thin layer of water means that it does not take long for your body to warm it. And this costs you less of your body heat. 

Now once saturated, freshwater can no longer move into the suit, even when you move around in the water. This is why you stay warm in a wetsuit, and explains why it is important to have a tight-fitting suit. Making sure that your wetsuit fits snugly around the ankles, wrists, and neck is the best way to stop the warmed water from escaping.

A baggy wetsuit means water will flow in and out of your wetsuit, and more water will enter at once. This will cost you a lot more body heat to warm. The water will also not reach a temperature warm enough for the suit to be effective, as it will flow out of the suit and be replaced by fresh, cold water. And this means that you will remain cold.

So understanding that the right fit is essential to how a wetsuit works is step one.

Insulation

Now that a thin layer of water has moved through the wetsuit and sits between it and your body, pressure from the suit material, neoprene, and your body, keep it in place to be warmed.

Neoprene is an effective insulating material, but it is not perfect. some of your body heat will escape through the material and will be wasted. This heat will pass through the neoprene and have a slight warming effect on the water immediately outside of your suit.

Whilst this happens, the thin layer of water trapped inside your wetsuit will lose some of its heat. This means that along with warming, a wetsuit is also constantly losing heat generated by your body.

Now we must look at the thickness of a wetsuit. The thicker the neoprene, the less body heat will be lost. For example, a 3mm wetsuit loses more heat than a 5mm one. This is because there is a thicker wall of insulation between you and the cold water outside.

Radiation

Some wetsuits have a titanium lining, which is a silvery material with a degree of reflecting ability. This is designed to radiate heat back to your body.

There are strong claims surrounding the effectiveness of titanium lining, especially from manufacturers. However, tests show that the extra warming effect is small, and hardly noticeable when compared to wetsuits without a titanium lining.

The main reason for this is simple; titanium is not great at reflecting heat. Secondly, manufacturers will usually put this lining behind the nylon lining. This massively reduces its reflective capabilities further. A third point is that the interior of your wetsuit is black, and so will poorly reflect heat. This means that not enough of your body heat will reach the reflective titanium lining.

If a wetsuit material does not have a nylon coating on the inside, then a titanium lining is not an uncomfortable finish next to the skin. This gives it the best chance of actually reflecting heat back to your body, but there are few manufacturers that produce wetsuits this way.

Overall, titanium lining as a form of heat radiation control, will not reduce the effectiveness of your wetsuit. However, by doing a testing and scientific reading, you will see that this wetsuit feature is blown out of proportion. So when buying a wetsuit, this criteria should not be at the top of your list.

Build

A tight fit around the wetsuit openings is important in how the suit works. But zip and seams also play a part.

No matter the material, a small amount of water will always slip through stitching and seams. It will never be a large amount of water, and in some suits, this is not a problem.

Wetsuits designed to be used in the summer will have a flatlock stitch, and this allows water to seep slowly. In a 3mm wetsuit, this is fine, as the suit will be effective enough that the user will stay warm, even if some water is escaping through seams and material.

But in colder winter conditions, it is vital that water seepage is stopped at every possible chance. This means using different techniques to block the seams, where water easily escapes.

Blind stitching is one method used to achieve this. Here the needle and thread do puncture all the way through the neoprene. Therefore, the needle does not leave a hole for water to pass through. For the blind stitching to work properly, panels of neoprene need to be glued together. Then they are stitched from both sides, making sure no needle holes are left.

Taping the inside of seams is an alternative to glueing. And this is also effective at reducing seepage. And finally, liquid seams is another technique used by manufacturers. Similar to glueing, a liquid seam is one that has had a liquid rubber material applied to the inside. It sets and forms a watertight barrier.

Zips

You can find wetsuits with what are called ‘dry zips’ instead of regular zips. A dry zip can hike up the cost of a wetsuit, so consider this.

A wallet-friendlier way of reducing water coming in through the zip is to use a zip baffle. Zip baffles, also called ‘bat wings’ are a piece of material placed behind the zip to stop water from going through the zip teeth.

Coating

 You will find the majority of wetsuits made out of double-lined neoprene. ‘Double lined’ comes from the fact that the rubber is laminated to a fabric. This is most often stretchy nylon and adds to the suit’s durability.

If these kinds of wetsuits are worn for activities where the user is not submerged in the water, then ‘evaporative cooling’ takes place. This is where the nylon fabric retains a small amount of water, and escaping body heat warms it.

However, a stronger and cold wind will blow away this layer of water and heat. Smooth skin neoprene can help reduce the effect of this, especially on larger surface areas like the torso. Smooth skin neoprene is just neoprene with laminated nylon on one side.

The other side is, therefore, smooth neoprene. Because the smooth neoprene holds less surface water, less evaporative cooling takes place.

A downside of this, however, is that smooth skin neoprene is less durable. For this reason, it is not used all over a wetsuit.

It can be argued that the benefits of smooth skin neoprene are exaggerated. It does reduce evaporative cooling, but the benefits are not seen by everyone who wears this kind of wetsuit.

First of all, if your activity has you in the water constantly, such as swimming or diving, then you will not experience evaporative cooling in the first place. And secondly, in most above water sports such as surfing or jet skiing, you spend more time in the water anyway. Along with this, many above water sports require the use of a life jacket, which further blocks wind.

You will feel slightly warmer when wearing a smooth skin wetsuit, but it is important to know that their effect has arguably been blown out of proportion.

Another outer material used in wetsuits is fine mesh. It is similar to smooth skin, but the finish is a little more durable. But just like smoothing, fine mesh is also designed to retain less surface water than standard neoprene.

Conclusion: How Do Wetsuits Work?

To conclude, we’ve covered a range of components that make a wetsuit work. This was a pretty comprehensive overview, so hopefully, you now have some sort of idea about how they work to keep you nice and warm whilst in the water. But for those who like to dive a little deeper, you can look into the material science behind neoprene.