Wetsuits and rash guards seem similar at first. Both are protective layers that are designed to be worn in the water, and to the untrained eye, a rash guard may seem like a thinner wetsuit. However, there are some major differences between these two pieces of gear, and this article will go over what separates them

Rash guards are designed to protect your skin against rashes by placing an extra layer between your skin and the board. They are NOT effective at keeping you warm in the water unless worn with a wetsuit. If you want better protection than a rash guard offers and you want to stay warm, then look for a wetsuit instead.

What is a rash guard?

Rash guards, also known as rashies and rash vests, are a type of protective clothing commonly worn by surfers to prevent their torsos from rubbing against the rough surf wax on their boards to prevent getting a rash.

Sun protection

If your wetsuit has a UPF rating, then that means it also pull double-duty as a layer of protection against the sun’s UV rays. On hot days where you’d toast in a wetsuit, a rash guard is a lighter, less restrictive, and just as effective way to protect your skin against sunburns. The more you cover up your skin with UPF clothing, the less reef-safe sunscreen you need to use which is very convenient and cost-efficient.

On cooler days, many people will use their rash vests as a base layer to be worn underneath their wetsuit. This not only keeps you extremely warm, but it can also protect sensitive areas like the neck and underarms from chafing against the wetsuit seals and seams.

Can be worn as a base layer

Though most rashies are not designed to keep you warm (try wearing one on a windy day, you’ll freeze), some of them are made with special material that offers better insulation. For instance, the Rip Curl Flashbomb Polypro uses polypro lining, which is a lightweight, fast-drying fleece material that is proven to be very effective at insulating body heat.

Rashies can be either tight fitting or loose-fitting, depending on your preference. If you think you might wear it under a wetsuit, you need a snug fit so it won’t wrinkle or bunch up when used as a base layer. If you plan on just using it as UV and rash protection, then a loose-fitting one will suffice.

Conversely, sometimes rash vests are used by sailors to improve their performance while dinghy sailing. They’ll wear a loose-fitting one over their buoyancy device and other layers to reduce windage and prevent them from snagging onto other parts of the boat.

Maintenance

When cleaning your rash vest, we recommend doing it by hand in cold water without using any detergents. You do not want to accidentally remove the protective coating on the shirt which would reduce its sun-blocking effectiveness.

Prevents rashes

Is it any surprise that a rash guard can help prevent rashes? It’s even in the name! They are often used by surfers in the summer so that they can protect their skin from rubbing against the surfboard. As mentioned, they can be worn under a wetsuit as a base layer and this can also help reduce wetsuit rashes since the rash guard is preventing the wetsuit from directly rubbing against your skin.

What is a wetsuit?

A wetsuit can do everything a rash guard does, but its most beneficial feature is that it can keep you warm in cold water. Even though rash guards seem like they can offer you some insulation, most don’t and you cannot expect it to be as effective as a wetsuit. Wetsuits can be used like rash guards, but the reverse is NOT true.

Material

When shopping for a wetsuit, especially online, make sure to look for products that are made with neoprene. The neoprene material may also be laminated with nylon, spandex, polyester, or a similar fabric. If the wetsuit is not made with neoprene, it is not effective at keeping you warm.

Neoprene is a water-resistant material that is also flexible and an excellent insulator, making it the ideal material for waterwear. Inside the neoprene are thousands of bubbles that are very effective at insulating your body heat. These bubbles also provide buoyancy, so wetsuits make it easier for you to stay afloat.

Type

Wetsuits come in various styles. There are full-body wetsuits which cover your body except your head, hands, and feet. This obviously offers the most warmth and protection. Then, there are shortie wetsuits which only cover your torso, upper arms, and thighs. They provide more flexibility at the expense of less protection.

Shorties are often worn during the summer because they aren’t as unbearably hot compared to wearing a full wetsuit. Furthermore, the extra mobility improves one’s performance in whatever water activity they are doing, such as surfing or canoeing.

You can find wetsuits with varying thicknesses of the neoprene material. There are thin 1.5mm ones, but the standard wetsuits are 3mm, all the way up to 7mm+ for cold water use. The thicker the wetsuit, the more bubbles in the neoprene that can trap your body heat. Once the water gets too cold, then it’s better to wear a drysuit instead of a wetsuit to stay warm.

Fit

In order for a wetsuit to be effective, it should fit you very snug. This is not to keep the water out, but rather so that your body heat can be more easily trapped by the wetsuit. Some water will enter the wetsuit, but it will get warmed up by the body heat inside, effectively creating a layer of warm water around your body.

When ordering a wetsuit, consider ordering it a size or two too small so that it fits tight, but should not be suffocating or restricting your blood flow. A wetsuit that is too loose will allow water to flush out all of the body heat, defeating the purpose. Wetsuits that are tight at first will stretch out in the water over time so the fit will be more comfortable after you break it in.

Maintenance

Make sure to thoroughly rinse your wetsuit between dives, especially if you’ve peed in it. Read the care instructions that come with your wetsuit. Generally speaking, you should hand wash it and you can use a wetsuit cleaner if it has become particularly dirty. Do not put your wetsuit in the washing machine.

Wetsuit thickness and temperatures to wear them at

Water Temperature Range	Wetsuit Thickness	Recommended Wetsuit Type	Seal Type
>72°F (>22°C)	N/A	Rash guard	N/A
65°- 75°F (18° – 24°C)	0.5 mm – 2/1 mm	Top / Shorty	N/A
62°- 68°F (16° – 20°C)	2 mm – 3/2 mm	Springsuit / Full Suit	Flatlock
58°- 63°F (14° – 17°C)	3/2 mm – 4/3 mm	Full Suit + Boots	Sealed
52°- 58°F (11° – 14°C)	4/3 mm – 5/4/3 mm	Full Suit + Boots + Gloves + Hood	Sealed and Taped
43°- 52°F (6° – 11°C)	5/4 mm – 5/4/3 mm	Full Suit + Boots + Gloves + Hood	Sealed and Taped
42°F (6°C)  and below	6/5 mm +	Full Suit + Boots + Gloves + Hood	Sealed and Taped

Differences between wetsuits and rash guards

The biggest difference between a wetsuit and a rash guard is that a wetsuit will actually keep you warm. The neoprene in the wetsuit is a very effective insulator that will retain your body heat even in cold water. However, this is also its downside: wetsuits have to be a certain thickness in order to be effective at retaining heat, and the thicker a wetsuit is, the harder it is to move around in.

We’ve already mentioned what a rash vest can do for you in the “What is a rash guard” section. Just know that a wetsuit can do everything a rashie can. Whether it is UV protection, rash prevention, even the mobility downside we mentioned above can be alleviated by wearing a shortie.

Should you buy a rash guard or wetsuit?

If we’re debating which one is “better”, we would have to say a wetsuit has more utility since it can do everything a rash guard can and more. However, not everyone wants or needs a wetsuit, so if a rash guard is enough for your needs, then just get that instead.

For example, swimmers, snorkelers and surfers who stay in warm waters may opt for a rash guard since it protects their skin against rashes and the sun’s rays. The UV rays are extremely damaging to the skin because it can cause you to age faster and put you at risk of cancer. Furthermore, sunburns are painful and can easily ruin your tropical island vacation.

With a rashie, you can also make your sunscreen lotion last longer because you don’t need to apply it to areas that will be covered up. Furthermore, even a rash vest can offer some protection against jellyfish stings.

On the other hand, if you want an even higher level of protection than what a rashie can provide, and you plan on heading out into temperate waters, then you need a wetsuit. Because of the wetsuit thickness, you have even more superficial protection, extra buoyancy, and warmth. You can even wear a shortie if you find a full-length wetsuit to be too warm.

Most wetsuits are 3mm thick, but you can find some shorter ones at 1.5mm or 2mm thickness which still provides more protection than a rashie can. Keep in mind, rashies can be worn with a wetsuit. It doesn’t have to be an either or situation. If the water you’ll be surfing, diving, or swimming in is on the colder side, you can wear a rash guard under your wetsuit for an extra layer of warmth.

When it comes to your safety in the water, you cannot be careful enough. You should be prepared with the proper equipment for the activity you will be doing. Do not underestimate what even a flimsy rash guard can do for sun protection. If you will be in warm waters, consider getting a rash guard or a shortie. If you’ll be in cold waters, get a thicker wetsuit and wear a rash guard underneath.

Have you ever peed in your wetsuit? Come on, don’t be embarrassed. Seriously. We certainly have. It’s nothing to be ashamed about, really. In fact, contrary to what people might deny face-to-face, when given the anonymity of the internet basically every diver admits to doing it, and it’s actually quite a beneficial and normal thing to do so.

The point of this article isn’t to shame you or gross you out. Quite the contrary, the goal of this article is to make the argument that you should proudly wee in your wetsuit. It can be kind of a taboo subject when divers speak openly about peeing themselves. There is always that look of disgust or a moment’s hesitation before changing the topic. However, this is a socially conditioned behavior and adhering to it only encourages the stigma.

Many argue that peeing in your wetsuit is unhygienic. We agree, wetting yourself is unhygienic… if you do it on land. If you’re underwater, it’s a different story. The pee can actually provide some temporary warmth before it’s flushed away. Plus, you have total control over how thoroughly you’ll rinse it before the next dive.

Furthermore, you’re not doing yourself any favors by holding it in. There are many more reasons why you should pee in your wetsuit instead of holding it in, as well as many myths about it that need to be dispelled, both of which will serve as the focus of this article.

Peeing while diving is normal

On average, a healthy human adult should urinate at least 4-6 times a day. When you’re diving, that number will be a little bit higher for you. There is a phenomenon known as immersion diuresis that occurs that makes you want to pee when you’re in cold water.

Immersion diuresis is the medical term for what happens to our body when we enter water that is cooler than the air. This process is part of our mammalian dive reflex which is our body’s way of preparing itself for longer submersion to increase its chances of survival. This physiological process is the reason why all humans have the urge to pee when we are in cold water.

Here’s a simplified explanation for what our body does. When your body senses that it’s in cool water, it wants to stay warm so it sends blood from the arms, legs, skin, etc. to the major organs of the body. With the organs now full of extra blood, one side effect is that the kidneys think that you have excess fluid in your body, causing it to increase urine production to balance out the fluids in your body. The end result is, you really need to pee.

Drinking less water to pee less causes dehydration

Some divers mistakenly think that the reason they want to pee every time they go for a dive is that they consume too much fluids before a dive, so they cut back on it. This is a serious mistake. Dehydration can lead to many problems for divers and can potentially increase the chances of getting decompression sickness. Thus, instead of cutting back, you may want to drink more water to ensure you are hydrated.

Furthermore, you should preferably be drinking water, not alcohol, coffee, tea, or any other diuretic beverages before a dive. These drinks can actually make you even more likely to pee and therefore even more dehydrated compared to regular water.

Unfortunately, few people understand just how easy it is to get dehydrated while diving. You will begin to lose water even before you enter the water by sweating. Once you’re actually in the water, immersion diuresis will cause you to produce more urine and make you want to pee. On top of all of that, you can lose fluids from breathing compressed gas because it has virtually no humidity.

As you can tell, there are so many ways that fluid loss and dehydration can occur while diving, and that’s why it’s a terrible idea to cut back on water before a dive. To top it all off, the more dehydrated you are, the more unpleasant your urine will smell. So, instead of trying to prevent peeing during a dive (which can be dangerous), focus instead on staying as hydrated and safe as possible.

It’s not healthy to hold your pee

When you’re on land, you wouldn’t hold your pee; you’d let it out at your earliest convenience. When you’re underwater, the earliest convenience is basically anytime you’re underwater. Holding it in does you no good no matter where you are.

Did you know that holding in your pee can lead to UTIs (urinary tract infections)? The most common cause of UTIs is not urinating after doing a certain cardiovascular activity in bed and then sleeping right away. UTIs are pretty terrible, but it’s not even the worst thing that can happen. In extreme cases, the urine can get backed all the way up to the kidneys and cause an infection which can be life-threatening.

On top of that, if you make it a habit to hold in your pee, you can damage your pelvic floor muscles which are the muscles that let you control urination and bowel movements. They are also necessary in the enjoyment of the aforementioned cardiovascular activity done in bed, so it’s not a good idea to damage these muscles. When you need to go, just go!

It’s distracting to hold it in

It was so refreshing to hear the owner of a dive shop tell me that he is perfectly okay with his Open Water students urinating in their rental suits, and in fact he encourages it instead of telling his students to hold it in.

You might be thinking that’s disgusting! Those poor students must be wearing the most pee-riddled wetsuits ever. It sounds gross, but the logic is sound. The layer of water inside of a wetsuit is slowly being replaced by fresh water, so the pee will eventually get flushed out. Also, the dive shop owner can spend more time at the end of the day sanitizing the suits.

This is much more preferable than having the students be distracted and uncomfortable with their full bladder which they will probably release anyways because they can’t hold it in anymore. The students should just be focused on the dive so that they can be on top of their game. The dive shop owner was willing to do extra clean-up later to give his students the best chances of excelling in the course.

Plus, there just shouldn’t be any taboo over letting your body do what it is naturally supposed to do. The same is true when you’re diving for fun. If the majority of your dive is spent trying to hold in your pee, you’re not focused or having fun are you? And if you’re not focused, you might be making some questionable choices during the dive.

Pee in your wetsuit for longer bottom times

It took me a long time to get over the mental hurdle that was preventing me from peeing in my wetsuit. I just couldn’t do it; I felt so ashamed that I was willing to cut many of my earliest dives short just because I couldn’t hold it in anymore and needed to urinate in a more “appropriate” location.

The day I finally decided to let go and do the deed underwater, I nearly cried tears of joy (okay, that’s an exaggeration). However, I decided that I cared more about having a longer bottom time than the shame of peeing in my wetsuit. And now I wonder what’s there to even be ashamed of? I think it was more shameful to surface so quickly and frantically try to doff my gear just so I could take a quick wee. My dive buddy was a saint for putting up with me.

If you struggle to make it through an hour-long dive, friend, just empty your bladder and dive in peace. It will be like you acquired a superpower that significantly boosts your bottom time. Holding in your pee is simply an unnecessary exertion that will decrease your bottom time. This is especially applicable if you will be spending several hours underwater; I don’t think it is even physically possible to hold in your urine that long underwater.

Urine won’t damage your wetsuit

Nor should it damage your pride. There is nothing in urine that will damage your wetsuit. No flesh- or neoprene-eating bacteria. Just 95% water, 2.5% urea, and 2.5% other stuff, and it’s not going to damage the wetsuit seams or weaken the wetsuit. So stop treating urine like it’s some kind of corrosive acid; it’s basically just water.

A very legitimate concern, though, is how hygienic the wetsuit is after it’s been urinated in. Particularly with wetsuit rentals, it can feel a bit disgusting knowing that it’s been peed in by so many people. If it’s your own wetsuit, you have complete control over how well it is sanitized before your next dive, which is why you should ideally wear your own wetsuit.

When you’re renting a wetsuit, perhaps you shouldn’t be so pee-happy because it’s not your property and is disrespectful. If you’re worried others have peed in it, you can conduct a sniff test to determine if any less-than-pleasant smells are still lingering, and ask for a different wetsuit if so.

If your wetsuit starts to smell a bit funky, use soap or a household cleaner to eliminate odors. There are wetsuit cleaning solutions designed specifically for this purpose too, though we never had a need for them because soap works just fine.

Peeing like a pro

We’re very much for peeing in your own wetsuit, which is why we are pros and know the best ways to do it. If you have to go, try to go near the start of your dive rather than the end. This gives the urine more time to flush out of your suit.

If you pee near the end of your dive, you better “flush” your suit! Don’t wait until you’re on land before you realize that you smell like a urinal. Flushing the suit just means letting water rinse your wetsuit, clearing out the urine if any still remains. There are two ways to do this; consider doing both just to be safe.

The first method is to grab the chest of your wetsuit and pull it away a few times, kind of like how you might fan yourself with a hoodie on land. Open up the feet, neck, and wrist seals on your suit to let the urine flush out in all areas. Repeat as needed.

The second method is a bit more complicated. Roll into a head down position and release some bubbles from your regulator into your suit from the neck seal. You can also use your octopus to flush air through the suit. Make sure you have sufficient air remaining before you do this step.

If you don’t want your pee to smell too unpleasant, avoid eating foods that make urine extra smelly such as brussels sprouts, asparagus, garlic, and salmon. If you don’t own the wetsuit, try not to pee in it regardless of what you ate. Some poor dive shop employee will have to clean it.

Stop feeling guilty for peeing in your wetsuit

To sum it all up, don’t let anyone make you feel like a weirdo for peeing in your own wetsuit. As we discussed, because of immersion diuresis, your body will naturally be more inclined to pee when you’re in cold water.

Holding in your pee just makes you distracted and uncomfortable during a dive. Letting it all go will enable you to do more advanced dives because you no longer have an arbitrary rule that you need to surface to pee outside of your wetsuit. Also, as long as you wash your wetsuit thoroughly afterwards, there’s basically no downsides to it.

The steps some divers take in order to avoid peeing during a dive is downright dangerous. For instance, cutting back on water can lead to dehydration and an increased risk of getting the bends. Also, holding in pee can potentially cause a kidney infection or damage to your pelvic floor muscles. It can also distract you and may cause you to make poor judgments during the ascent because you want to pee so badly.

None of that is worth it. The day you accept that it’s okay to pee in your wetsuit is the day you are liberated from uncomfortable, shortened dives, and can begin to enjoy scuba diving to a greater degree.

You might be interested in reading about if it’s okay to fart in a wetsuit next, or if you’re feeling brave, read our article about pooping in the ocean.

Wetsuits are insulating pieces of water equipment that covers most of the body (from neck to ankles and wrists) or in parts such as vests and shorts. Just like cold-weather clothing, wetsuits are designed to keep your natural’s body heat from escaping and to protect against abrasive hazards like sharp rocks and coral.

Thanks to its neoprene material, skin tight fit, and water-resistant construction, the cold water that enters the wetsuit will quickly get warmed up by your trapped body heat. Instead of suffering every time you’re swimming in cold water, it’ll feel like you have a constant layer of warm water protecting your body from the cold. That’s a highly simplified explanation of how wetsuits keep you warm.

In this article, we’ll go over the science behind how wetsuits work, the intricacies of their design, and various ways you can select the best wetsuit to keep you warm.

How does a wetsuit keep you warm in cold water?

Most wetsuits are constructed by combining neoprene rubber laminated to nylon, spandex, polyester, or a similar fabric. The benefit of this is the material can stretch for a snug fit as well as give you the range of motion to move your body without compromising the quality of the suit.

Wearing a wetsuit is like putting on a second, thicker layer of skin that can protect you from the cold and other, more physical hazards such as jellyfish stings and coral. Specifically, this “second-skin” is waterproof and has thousands of air bubbles trapped inside it that prevents heat from escaping.

Though we tend to think of the wetsuit as an entire layer on its own, actually it is composed of three to four layers and each has a different purpose:

• Comfort (inner) layer. This is the innermost layer that will have contact against your skin. It is designed to be softer and smoother to discourage chafing and promote comfort.
• Heat-reflecting layer. This layer is made of some kind of heat-reflecting material that prevents body heat from passing through it. It does a similar job to the neoprene layer. Not all wetsuits will have this layer.
• Neoprene layer. This layer comprises the bulk of the wetsuit construction and will have varying elasticity and thicknesses (3mm to 6mm+). The bubbles trapped inside neoprene are excellent insulators and also make the wetsuit positively buoyant. Hypoallergenic wetsuits do not have any neoprene because it can sometimes cause allergic reactions in individuals.
• Outer layer. This layer is made of durable and resilient material that protects the wetsuit from wear and tear.

The more layers your wetsuit has, the greater the insulation it will provide. This is because each layer traps warm air between them, and actually it is this air that keeps you warm, not the warm water. It’s also why wearing a base layer under the wetsuit can be so effective at keeping you warm, because it is yet another layer. Conversely, this also means that if you only have one layer, no matter how thick it is, air will more easily find its way out.

A snug fit

In order for a wetsuit to be effective, it needs to fit snug on your body. It should not be so constrictive that you cannot move, struggle to breathe, or disrupt your blood flow, of course. However, it does need to lightly press against your skin to provide effective insulation from the cold.

As we mentioned, some water will enter your wetsuit so don’t be alarmed when it happens. Despite being soaked, there should only be a thin layer of water between the suit and your body. Your body heat will be trapped inside, warming up the water as well. In a high-quality wetsuit, the warm water will mostly be trapped with very little cold water entering and warm water leaking out.

Conversely, in a baggy or low-quality wetsuit, cold water will constantly rush in and flush out any warm water. The cold water will make contact with your skin and steal your precious body heat away. You will constantly feel cold if the wetsuit doesn’t fit you snug enough which defeats the purpose of even wearing it.

For this reason, you need to find a snug wetsuit because it will be much more effective at keeping you warm than a baggy one.

Heat retention

Why is it so important to retain your body heat in the water? Water is about 25 times more effective than air at taking heat away from your body due to its higher density and heat capacity. According to physics’ second law of thermodynamics (i.e. the science of heat transfer), heat will flow from a hotter object to cold objects nearby.

Take for example, your own internal body temperature of 36°C. When you expose yourself to cool air that is 15°C, your temperature will drop as the heat moves into the air, and you will experience this as a chilly wind. When your body is in a body of water, even “warm” water, the result is that your core temperature will be rapidly cooled since water is so much more effective than air at transferring heat.

This is the same reason why you could spend an hour on a hot sunny day swimming or snorkeling, and come out of the water shivering with blue lips. The entire time you were in the warm water, it was bringing your body’s temperature closer to the water’s temperature which can cause hypothermia in the human body.

To combat this, wetsuits are made up of many layers that trap your body heat. Each layer acts as a type of “airlock” that the air tries to flow through. Since air is mostly empty space, each layer makes it harder for the air to pass through, and this is known as insulation. With the hot air trapped inside and so close to your body, you will stay warm.

Without a wetsuit, the water molecules will draw the energy, or heat, from your body faster than your body can replenish it. Even in warm waters, if you plan on spending a long time in it, you should consider wearing some kind of protection.

Wetsuit thickness and temperatures to wear them at

Water Temperature Range	Wetsuit Thickness	Recommended Wetsuit Type	Seal Type
>72°F (>22°C)	N/A	Rash guard	N/A
65°- 75°F (18° – 24°C)	0.5 mm – 2/1 mm	Top / Shorty	N/A
62°- 68°F (16° – 20°C)	2 mm – 3/2 mm	Springsuit / Full Suit	Flatlock
58°- 63°F (14° – 17°C)	3/2 mm – 4/3 mm	Full Suit + Boots	Sealed
52°- 58°F (11° – 14°C)	4/3 mm – 5/4/3 mm	Full Suit + Boots + Gloves + Hood	Sealed and Taped
43°- 52°F (6° – 11°C)	5/4 mm – 5/4/3 mm	Full Suit + Boots + Gloves + Hood	Sealed and Taped
42°F (6°C)  and below	6/5 mm +	Full Suit + Boots + Gloves + Hood	Sealed and Taped

Stitching

If you’re not aware, wetsuits are actually constructed from various pieces that are stitched together to form one large piece. Everywhere there is a stitch is a small hole that water can seep in from. Water is tricky to deal with because even the tiniest of spaces can cause a leak. The more water that can enter the suit, the less effective it will be at keeping you warm.

Wetsuit manufacturers are aware of this problem, of course, so they have various stitching methods to keep water seepage to a minimum. Water should only be entering from the neck, ankle, and wrist openings. The wetsuit seams are typically made using the flatlock or blind stitch method. These two styles provide different levels of water sealing capability.

With the flatlock type of stitching, a needle will go through both ends of the fabric in order for the thread to pass through. No matter how tightly-knit it is, water will find its way through because of the top-to-bottom holes that the needle opened up. For summer wetsuits, this type of stitching is suitable since temperature control is less of a concern.

Blind stitching is a more waterproof way of knitting two pieces of cloth together. The two pieces of fabric are glued together. Then, the needle and thread are used to bind the pieces together. The wetsuit will be sewn in such a way that the needle doesn’t actually pierce all the way through to the other end of the fabric.

The manufacturer may even tape tape over the seams for yet another layer of water protection. Wetsuits made this way are effective at preventing water seepage and will keep your body warm in the water.

Zippers

We’ve already mentioned how water can enter from the ankle, wrist and neck opening and flush out the warm water inside. However, water can also enter from the seams and zipper. In a high-quality wetsuit, even these are minimized or outright prevented.

For instance, some wetsuits have dry-zips (just like those found on drysuits) instead of a regular zipper. This prevents any water ingress, however this can also double the cost of a wetsuit. In our opinion, the cost is not justified for the little benefit it provides. If you care very deeply about staying warm, however, then it is something to consider.

A budget way to prevent water ingression through the zip is by including a zip baffle (or a “batwing”) which is an extra piece of material that follows behind the zipper and blocks any water from going past it.

Be wary of evaporative cooling

The traditional wetsuit design is effective for heat retention while underwater, however above water there is an evaporative cooling effect. When performing water surface activities such as surfing or kiteboarding, the wind will blow away the layer of water directly above the wetsuit, taking away the heat accumulated. This is known as evaporative cooling, and as your suit builds up another water layer, it will also be lost to the wind.

To show this in effect, you can do a very quick test right now. First, blow against the back of your hand. That probably didn’t feel very cold, did it? Now wet your hand and try blowing again. It should feel significantly colder. Even with the protective layer of a wetsuit, you can still feel cold above water with a wetsuit due to evaporative cooling.

In order to prevent this, you can wear a smoothskin neoprene wetsuit. The smooth surface of this type of wetsuit causes water to easily slide off, thereby reducing the effect of evaporative cooling. While this solution does work, it may not be necessary.

If your water sport activity is diving, you will spend most of your time underwater where there is no evaporative cooling. Even for an above water sport like surfing, surfers will spend most of their time underwater as they wait for a good wave. Even other above water sports like sailing, kayaking, and water skiing require one to wear a buoyancy aid which offers some protection against evaporative cooling.

Finally, evaporative cooling will occur whether you wear a wetsuit or not. Even a wet wetsuit on the surface will offer you some insulation against the cold-amplifying effects of evaporative cooling. The concept of evaporative cooling is something to keep in mind, however in many situations it’s not a problem.

Emergency warmth

There is a technique which we hesitate to recommend, though it can be handy in an emergency. Many people lament the fact that swimmers like to urinate in the pool, and the same is true for the ocean as well. When you’re in a wetsuit and you don’t have easy access to the bathroom, then when you gotta go, you gotta go.

In a pinch, weeing in your wetsuit (known affectionately as a “wetsuit warmer”) can temporarily provide some much needed warmth. The urine is the same temperature as your body so it’s already going to be a comfortable temperature. The thought of swimming in your own urine seems disgusting, but keep in mind, water is constantly being replaced in your wetsuit. Eventually, all of the wee will be washed out and replaced with ocean water.

If you are shivering and need a temporary reprieve from the cold, consider using a “wetsuit warmer.”

Parting words

To sum it all up, wetsuits can keep you warm by trapping your body heat and keeping it close to your skin. Water will enter your wetsuit, get warmed up, and add another layer of insulation inside the suit. The goal is to keep as much water out as possible so that the warm water inside is not immediately flushed out, and your body temperature can remain high.

There are various considerations to keep in mind when purchasing a wetsuit. It is completely useless if it does not have a snug fit on your body. It should also be an appropriate thickness for the water temperature you will be wearing it in. Depending on the stitching method used, flatlock or blind-stitched, water may seep in through the seams as well as zipper.

In addition to keeping you warm, wetsuits add an extra layer of protection against cuts, scrapes, and marine life such as jellyfish. Whether you’re a surfer, snorkeler, or SCUBA diver, you can surely benefit from wearing a wetsuit if you’ll be spending a lot of time in the water.

Not everyone wants to wear a wetsuit to stay warm, so many people are turning to rash guards to keep them warm while surfing, kitesurfing, snorkeling, and other similar water sports. Can rash guards keep you warm the way wetsuits can?

Rash guards are a type of swimwear that can provide a little bit of warmth on their own, however that is not their primary purpose. In fact, you should not be expecting a rash guard to keep you warm in temperate or cold waters at all; they are best suited for warm water use or to be worn underneath a wetsuit as a base layer. In warm waters, you can be kept comfortably warm.

In this article, we’ll go over the various benefits that rash guards provide, including how they can keep you warm, and why this versatile piece of clothing should be used by everyone who participates in water sports.

How effective are rash guards at keeping you warm?

Rash guards are not very effective at keeping you warm. That’s what a wetsuit or drysuit is for. Rashies are quite thin, often with a thickness of only 1.5mm and made of breathable material like lycra and polyester.

That’s not to say that rash guards don’t provide any warmth, just that you shouldn’t expect to wear it in cold water or on an extremely windy day and expect to feel cozy. Instead, what you can do is wear a rash guard underneath a wetsuit to provide an extra layer of warmth.

There are some rash guards that are specifically designed to provide protection from the cold. They are constructed from thermal materials such as neoprene, which is the same material wetsuit are made of. However, if you have to resort to this then you might as well just wear a wetsuit instead.

Just how much warmth does a rash guard provide? Again, not much. You can perhaps expect to feel one or two degrees warmer in the water. If you’re wearing a rashie just for warmth, you’re using the wrong tool for the job; a wetsuit is way better for heat retention. With that said, rash guards are beneficial in many other ways, and when paired up with a wetsuit they can make you feel extremely warm.

Do I need a rash guard?

When people think of a rash guard, they often only think about the shirt portion that either has long or short sleeves. However, the term rash guard also encompasses the protective leggings, which can also be long or short, and offers the same protection for the lower half of the body. Together, they provide a layer of protection kind of like a second skin, against various dangers present in water sports activities.

Rashies can be made from various materials, from spandex, nylon, polyester, all the way to luxurious fleece. It will protect your skin against constant rubbing against equipment, minor cuts, the cold, and even the sun’s UV rays. While the protection it provides is limited, it’s better than nothing. Overall, they are a lightweight and breathable solution compared to a wetsuit. In fact, you can wear a rash guard underneath a wetsuit for even more protection!

Types of rash guards

You can find three different types of rash guards:

1. Long sleeved.
2. T-shirt (short-sleeved).
3. Sleeveless (a.k.a. Rash vests).

We’ve mentioned already that rashies can come in various thicknesses, depending on your needs. To help you narrow down which style is best for you, consider what activities you plan on doing while wearing the rash guard.

If you want total protection and as much warmth as possible, obviously you want to go for the long-sleeved variety. If you want to flex your guns, then a sleeveless vest would be the ideal choice. If you’re going to be spending your time lounging around and occasionally going into the water, a T-shirt rashie will offer a good mix of protection and comfort.

What is the purpose of a rash guard?

They are an alternative to wetsuits for warm water activities

If you’re surfing, snorkeling, or diving in warm waters and you want to layer up without resorting to a wetsuit, what are your options? This is the perfect time to wear a rash guard. Rash guards are made out of quick-drying material, and they offer some protection without being as restrictive or hot as a wetsuit.

However, if you will be in cold or even temperate waters, rash guards aren’t going to cut it anymore. In this case, they can still serve a purpose by providing a base layer underneath your wetsuit. If you decide to do this, then you need to make sure your wetsuit has some extra space inside to accommodate your rash guard.

One of the great things about rash guards is that, like wetsuits, they come in various thicknesses. They are typically around 1.5mm, but if you need more insulation, you can get a thicker one. For warm warm activities like swimming, a thinner rash guard will do do the job.

They protect against chafing

The primary objective of a rash guard is to protect the wearer’s skin from chafing and rashes. This is a well-known issue in the surfing community that the wax applied to surfboards, salt from the ocean, and friction of your skin against the surfboard and clothing can cause extreme discomfort.

Rash guards are constructed from flexible, breathable materials so that they do not chafe your skin or restrict your movement. Furthermore, some rash guards have a UPF-50 rating meaning they can block the majority of the sun’s harmful UV rays so that you don’t get sunburnt.

They provide some warmth

The average rashie does not provide much warmth, but the material it is made from will make a big difference. Many larger brands are now making rash guards with fleece material, or thermal rash guards, and they are comfortable and much warmer than your standard one. With that said, they cannot compare with the insulation that a wetsuit can provide.

A typical rash guard made of nylon, spandex, or polyester and worn on its own will not provide much protection against the cold. Most rashies are only 1.5mm thick, so they are  considerably thinner than a wetsuit which is often 3mm or thicker, and made from a very effective insulating material called neoprene. However, you can wear a rash guard AND a wetsuit together, so it’s not like these are competing pieces of gear.

Furthermore, thanks to how breathable rashies are, they are also quick drying and very comfortable. Outside of the water, the increased air flow will dry your skin and the rashie faster, making you feel warmer. Some rash guards are also wind-resistant and will keep cold air from chilling your skin. A cheap rashie will not be able to provide much warmth, but a high-quality one sure can.

They protect against cuts and marine life

You never know what might be lurking in the water. It’s very easy to get cuts from sharp rocks, coral, or debris. It’s also easy to get stung by jellyfish and to come into contact with sea-lice that can irritate your exposed skin. Though rash guards are light, they do provide a protective layer so that you can minimize damage.

Creatures like sea-lice, anemone, and jellyfish often sting through light touch. A rash guard can actually be effective at protecting you from these light stings. What a rash guard will NOT protect you from are sharp stings such as from a scorpionfish or an urchin spike. 

They provide sun protection

If you’re going to spend many hours in the sun, you’re going to need some sun protection. What better way than to wear a rash guard? There are some rash guards that have a UPF rating (the equivalent of the SPF rating for sunscreen, but for clothing), which means they are designed to block UV rays from penetrating the material and reaching your skin.

Beware of purchasing a rash guard that does NOT offer any UV protection. Furthermore, do not think that any piece of clothing offers adequate sun protection. You must specifically wear clothes with a UPF rating in order to be protected. Low quality rash-guards may be weak and fail to provide sun protection or warmth.

The great thing about wearing a rashie for sun protection is that, unlike sunscreen, you do not need to reapply it. It covers a large portion of your body and will help you conserve a lot of sunscreen. You still need to wear sunscreen, but only on the exposed areas of skin and not your entire body. Apply reef-safe sunscreen on areas that aren’t covered by the rash guard 30 minutes before heading into the water for the ultimate protection.

They can be used for land sports

Rash guards are popular for many water sports, such as SCUBA diving, swimming, kayaking, kitesurfing, SUP boarding, snorkeling and the like.

With that said, these lightweight shirts can be worn for any physical activity where you want to protect the skin from chafing and cuts. Since rashies are so breathable and fast-drying, any water or sweat will quickly evaporate from it in no time. In other words, they are just so comfortable and versatile.

Rashies are commonly used outside of the water for activities like mixed martial arts, baseball, and even football. As you can see, these are all activities that require great mobility which could lead to chafing if one doesn’t wear a rash guard. Professional athletes will often wear rash guards under their uniforms.

Furthermore, just like how rashies can offer minor protection against cuts in the ocean, they can do the same in combat sports like jiu-jitsu where cuts, burns, and infections are commonplace. To sum it up, rashies are flexible and lightweight enough to allow for unrestricted movement and are quick-drying thanks to how breathable they are.

How to wear a rash guard

Rash guards can have a tight fit like a wetsuit, or they can have a loose fit. Most people prefer a tighter fit, like a second skin, because it is more functional. The more form-fitting it is, the less room for water or debris to get underneath.

Furthermore, if there is less (or no) excess fabric getting in the way or producing drag, then wearers can swim and move around much easier. If you are a SCUBA diver or surfer, you definitely don’t want the extra risk of getting tangled up in your own gear.

However, if you plan on spending the majority of your time on land, or the climate you’re in is extremely warm, then a loose-fitting rash guard, perhaps even in the T-shirt or vest style, could work fine. As long as you’re safe and still able to do what you want, it’s all down to personal preference. Some people find tight clothing to be claustrophobic and would rather wear looser clothing.

Parting words

Overall, rash guards do not provide much warmth however they are extremely effective at protecting the skin from rashes, the sun, and various skin irritations. There are various factors to consider when purchasing a rashie, such as the type of style, how tightly it fits, if it has a UPF rating, and so on.

If you really want to stay warm with a rash guard, they can be worn underneath a wetsuit for yet another protective layer. Even on its own, you can expect it to provide minimal warmth depending on how tight fitting it is. A loose-fitting rashie will allow water to constantly flush through the suit and sap your warmth. A more form-fitting one can may be able to insulate some of your body heat. If you truly  want to stay warm in the water, get a wetsuit instead.