Being an avid surfer, swimmer, and skimboarder, I feel like I’ve been wearing rash vests for about as long as I can remember.
Through trial and error, I’ve learned quite a bit about them over the years.
Rash guards (sometimes called rash vests or rashies) are form-fitting garments made from synthetic materials like spandex, nylon, and polyester — and are intended to block UV rays and prevent chafing during swimming, surfing, and other activities in or near the water.
Over the years I've written a lot about rash vests, wetsuits and other swim attire.
Below I’ll answer 12 of the most common questions I receive about wearing, caring for, and choosing the best rash vests for any activity.
What Do You Wear Under a Rash Vest?
For the ladies, a swimsuit, swim bra, or bikini is typically worn under a rash vest, with a two-piece being the most common choice. Wearing a regular bra or sports bra isn’t recommended as both salt water and chlorine are likely to damage them.
If you wish you can wear nothing under your rash guard but just know that this may expose more than you would like depending on the thickness, material and color of the rash guard.
Because rash vests are relatively thin, they tend to cling to the wearer and become semi-transparent when wet. A swim bra or swimsuit worn beneath will provide both support and modesty.
Typically, bikinis are preferred over one-piece swimsuits to make changing and using the bathroom less of a headache.
Just keep in mind, whatever you decide to wear under your rashie will become pretty visible the moment you get wet — including any decorations, textured patterns, and knot ties.
Zippers, plastic or metal hooks, and solid decorations should also be avoided because they may snag or tear your rash vest. A smooth, plain base layer works best.
For men it's generally recommended that you wear nothing under your rash vest. The rash vest is enough and all you need.
If you want to add warmth then you should wear an insulated rash vest or you should wear a wetsuit instead.
Do I Need a Rash Vest Under My Wetsuit?
Generally you don’t need to wear a rash guard under your wetsuit. It restricts movement, adds water weight, and, unless the rash vest is insulated, doesn’t provide any additional warmth.
It may seem logical that adding layers under a wetsuit would provide more warmth. After all, when we dress on a cold winter day, it’s all about the layers.
But wetsuits don’t quite work the same way.
The goal of a wetsuit is to fit snug enough to trap a thin layer of water between you and the suit, which can be warmed quickly by your body heat.
Adding a standard rash vest beneath a wetsuit is, at best, neutral and, at worst, can make you colder by allowing more water to enter the suit than your body can efficiently heat.
That being said, there are some situations where it can be beneficial to toss a rashie under your wetsuit:
- Thermal rash guards do provide additional warmth to your wetsuit, at the cost of additional material. If you opt for an insulated rash guard, you may need to size up your wetsuit.
- If your wettie is a bit too big (and letting too much water in), a rash vest underneath may help you achieve a better fit and keep you warmer.
- If your wetsuit causes chafing, a rash vest can help reduce or eliminate it altogether.
Generally speaking you should either wear basic swimmers or nothing at all under your wetsuit and should wear a rash guard instead of a wetsuit on warmer days when you don't need the insulation.
Should a Rash Vest Be Tight?
When deciding how tight your rash vest should be, it’s important to consider the type of activity you’ll be doing. For high-performance activities where chafing is likely or loose fabric may be cumbersome, a form-fitting rash guard works best. If you’re just spending a day on the boat, beach, or trail, a looser rash guard will work just fine.
Rash guards range from form-fitting to loose (a fit similar to a t-shirt).
Form-fitting rash guards are intended for water sports where loose fabric can add resistance and impede performance — like surfing, swimming, and skimboarding. Tighter rash guards are also more effective at minimizing chafing.
It's also important to note that rash guards do stretch a bit once they get wet and they do tend to stretch over time. Form fitting rash guards are generally seen as more stylish and are more common these days.
However, some people prefer looser fitting rash guards as these offer more modesty and don't show up every curve and lump of your body.
Loose rash guards, sometimes called surf tees or swim tees, are great for providing sun protection and wicking moisture during more laid-back activities — like paddleboarding, hiking, or just chilling on the beach.
Do Rash Guards Stretch Out?
High-quality rash vests that are cared for properly won’t stretch out or lose elasticity very quickly. Of course, as with any garment, they will eventually wear down and need to be replaced.
Rash guards are commonly exposed to chlorine, salt water and UV rays as well as being water logged for a large majority of their wear time. This inevitably leads to sagging in the rash guard material.
Generally speaking you'll get 1-2 seasons out of a rash guard before it has stretched so much it needs to be replaced. The less you use it and the better you take care of it the longer it will last.
To prevent a rash guard from stretching out prematurely, proper care is required:
- As soon as possible after every use, rinse your rashie in cool, fresh water to remove contaminants like salt and chlorine that may damage the fabric.
- Wash the rash guard every couple of uses by turning it inside out and hand washing gently in cool water with a biodegradable soap.
- Hang to dry out of direct sunlight and away from excessive heat. Squeeze out excess moisture as it hangs to speed up the process.
- Store your rash vest by hanging it on a wide-shouldered, padded hanger indoors (not in your trunk!). Regular wire hangers may stretch the fabric over time, wetsuit hangers work great. Folding or bunching a rashie can make the fabric weaken at the creases.
- Don't manually stretch the rash guard by pulling it down or (as my kids often like to do) sticking your knees inside it on cold days or filling it up and using it to carry a lot of sand on hot days.
How Long Do Rash Vests Last?
A high-quality rash vest can last for years when cared for properly but usually a rash guard will only last 1-4 seasons with regular use. Eventually it will stretch and become saggy and need to be replaced.
To extended the life of your rash guard rinse after every use, hand wash with a mild soap, hang to dry, and store on a padded hanger or wetsuit hanger. Fading and wearing are early signs that your rash guard is losing its UV protectiveness and should be replaced.
There are too many factors involved to give a specific estimate for how long a rash vest may last. The quality of the rash guard, how well it’s cared for, how often it’s used, and what it’s used for all play a role.
On average, 3-4 seasons is a reasonable expectation for adult rash guards and 1-2 seasons for kids rash guards. This is because kids always seem to stretch their rash guards out somehow and sagging happens much faster. They tend to grow out of the rash guard by the 2nd season anyway.
Outside of tears, rips, and other obvious damage, the first signs that rashie should be replaced are faded colors and worn, thin-feeling fabric — both indications that your rash vest may be losing its ability to protect you from the sun and well on it's way to becoming a loose saggy bag.
Does a Rash Guard Make You Hot?
Rash vests aren’t intended to keep you warm, they’re intended to protect against chafing and the sun. In the water, rash guards shouldn’t be relied on for warmth — use a wetsuit instead. Out of the water, rash guards will actually help keep you cool by blocking UV light and wicking moisture.
Generally, rash guards cannot be relied on for warmth while swimming or surfing. They don’t trap body heat like a wetsuit and may actually make you feel colder when exposed to the wind.
This is because as the wind blows across your rash guard some of the water evaporates which then makes the remaining water in your rash guard colder.
If you've ever swum on a day with a cold wind and gotten out of the water you'll know how being wet can make you so much colder in the wind. Rash guards exacerbate this problem.
The exception to this is dark colored rash suits on hot days. When dry the dark colors will absorb more of the suns heat and so will keep you warmer than if you were wearing a light colored rash guard or none at all.
Are Rash Guards Breathable?
Rash guards are made of relatively breathable fabrics like nylon, spandex, and polyester. Though the exact breathability depends on the size of the yarn and the knit or weave.
Regardless of how breathable a rash guard is, they make great hot-weather garments thanks to their ability to wick moisture and dry quickly.
Wicking is a fabric’s ability to move moisture to the exterior of the garment where it can evaporate quickly. When moisture is pulled away from the body, it takes some of your body heat along with it — boosting your body’s natural cooling system.
What Can You Use Instead of a Rash Guard?
The best alternative to a rash guard is a form-fitting spandex and polyester or nylon shirt. It will help protect you from chafing and abrasions, similar to a rash guard, but won’t provide the same UV protection.
The downside of wearing t-shirts over rash guards is that t-shirts absorb and hold more water which both weighs you down when trying to swim and also stretches and ruins the material.
Rash guards don't hold as much water and dry much faster meaning they hold their shape longer when wet.
If fit is the reason you don’t want to wear a rash guard, swim tees and surf tees provide many of the same benefits with a much looser fit.
When Should I Use a Rash Guard?
Rash guards are great to wear during outdoor activities to protect from the sun’s UV rays. When surfing, boogie boarding, or bodyboarding, a rash guard will help minimize chafing as well.
Generally when people think of rash guards, they think of water sports like surfing, swimming, and skimboarding.
But a rash guard is great for any outdoor activity (from hiking to lounging on the deck of your boat) thanks to their ability to keep the wearer cool and dry and protect against UV rays.
You should wear a rash guard whenever you're expecting to be outside, exposed to the sun for an extended period of time and when you anticipate that you might get wet.
I wear my rash guard in summer when I'm surfing, at the beach, swimming at the pool or doing other water sports like paddle boarding or even going to water parks. The rash guard keeps me protected from UV rays all day and I don't have to take it off when I go swimming.
I tend to avoid wearing a rash guard when it's cold and I won't be in the sun for very long or I wear a t-shirt when I don't think I'm going to get wet.
I don't wear a rash guard as a shirt for regular everyday use, though I know some people do when they are at the beach or the pool.
Do Women's Rash Guards Have Built-In Bras?
Very few women’s rash guards have built-in bras, but they’re becoming increasingly more common. A swim bra worn underneath your rash guard is a convenient way to add the support and modesty needed for your active lifestyle.
Can You Wear a Rash Guard as a T-Shirt?
Rash guards can be worn as a regular shirt in casual settings where an athletic shirt would be appropriate. Swim tees, surf tees, and other looser fitting rash guards tend to look best when worn away from the water. Save the high-neck, neoprene, and full body rashies for the beach.
While you can wear a rash vest as a shirt in casual settings, the best uses are really for outdoor activities where you’d benefit from the sun protection and moisture-wicking properties.
I’ll happily toss on a rashie for a day at the beach, hiking to a waterfall where I plan to swim or going paddleboarding. But there’s really not much benefit to wearing one to the mall.
Can You Tan Through a Rash Guard?
Unlike some swimsuits, you won’t be able to get much of a tan through your rash guard. They typically provide a UPF of at least 50, meaning the sun’s UV rays will have a tough time making it through to your skin.
Don’t forget to apply sunscreen to any area of your body your rashie doesn’t cover!