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The Gear Shed - Drysuit Layering

The Gear Shed - Drysuit Layering

Heading into Winter, it is important for boaters to review dry gear and advanced layering principles. In this article, we will discuss our layering formula for dry gear, different types of dry gear, and important considerations when using dry gear.

Why is Layering Important?

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The main goal of dry gear layering is to prevent:

  • Cold Shock

  • Hypothermia

  • Heat Related Illnesses

Cold shock is a physiological response to sudden cold-water immersion which can affect body movement, cognition, and respiration. Cold shock often results from immersion in icy or cold water.

Hypothermia is a condition where your body loses more heat than it can produce. Normally, hypothermia sets in when a patient’s body temperature nears 95 degrees Fahrenheit. As with cold shock, hypothermia can affect both body movement and cognitive abilities. For dry gear, hypothermia typically results from moisture retention within your dry suit.

Heat stroke and heat exhaustion can arise from excessive heat retention. Without proper layering, you won’t be able to adapt to changing conditions, or remove insulation to prevent heat stroke.

As with all layering strategies, the goal is to maximize flexibility and adaptability.

Drygear Layering Formula

Basic Layering Formula (Drysuit)
  • Lightweight layer

  • Midweight Layer

  • Primary Insulating Layer

  • Secondary Insulating Layer

  • Outer Shell Layer

These layers can be mixed and matched to create insulation systems that, once you become familiar with them, are customizable to any condition.  As boaters, we actively seek out water and immersion, whereas other athletes try to avoid it. Because of that, we must fundamentally change our layering formula. For example, our outer shell layers are a double-edged sword since they are usually not breathable due to their waterproofness.


Lightweight Layer

Lightweight Layer

  • Purpose – Wick moisture away from skin and regulate body temperature

  • Recommended Materials – Polyester and Polypropylene          

Lightweight base layers are designed to draw moisture away from skin, and to regulate body heat. On warmer days, this may consist of a short sleeve shirt and shorts but only if you have an additional layer on to prevent chafing. For colder days, it is best to use lightweight long underwear. Oddly enough, thin polyester dress socks are a highly effective and economical option here.


Mid Weight Layers

Mid-weight layer

  • Purpose – Wick moisture away from skin and prevent chafing under dry suit

  • Recommended Materials – Polyester and Polypropylene          

Mid-weight base layers also wick moisture away from the skin and regulate temperature like lightweight layers. These layers can also be used alone as moderate insulation on warmer days. Because these layers promote wicking, we recommend non-fleece fabrics. This layer also protects your skin from chafing under your dry suit.


1st Insulating Layer

Primary Insulating layer

  • Purpose – Trap heat and maintain core temperature

  • Recommended Materials – Microfleece, wool, or down-like insulation (for full dry suit only)

Heavyweight Insulating layers are designed to retain heat by preventing conduction. If you only have one insulating layer, fleece works best. Alternatively, if you’re wearing a full dry suit and you need an additional layer consider using a down jacket or vest. Thick wool or synthetic socks are your best option for footwear here.  


2nd Insulating Layer

Secondary Insulating Layer

  • Purpose – Increase heat retention in extreme cold

  • Recommended Materials – Microfleece, Wool

If you are rafting during extremely cold days, considering using a secondary insulating layer like micro-fleece or wool. This provides an additional barrier between the cold-outer layer and your body further preventing heat loss through conduction.


Outer Layer

Outer Layer

  • Hard shell layer – Moisture Impermeability

  • Recommended Materials – Nylon or Polyester

This is your dry suit or dry-top/paddle pant combination. This layer provides an impermeable barrier to seal out water. This layer is also highly effective against wind and prevents heat loss via convection between your body and cold water/air.

Gloves and Hats

               Your head and hands will be exposed to cold water, so we recommend applying the principles provided in our wetsuit layering article for hats and gloves.

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Material Guide

Dry Suit Materials

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Polyester – Polyester outer layers are hydrophobic and resist water absorption. Polyester is also resistant to UV damage, making it a great option for cold rivers with clear skies. One downside is that polyester is typically less abrasion-resistant than Nylon.

Nylon – Although nylon is like polyester in many ways, the key difference is that Nylon is naturally hydrophilic and absorbs water. By absorbing water, nylon dry suits can often “wet out” or allow natural conduction between body heat and water. Nylon dry suits also take longer to dry than polyester. Ultimately, Nylon dry suits are better for day trips or brushy rivers where hiking, climbing, or portaging is likely because Nylon is more abrasion resistant than Polyester.

Insulation Materials

Fleece (microfleece) – A wet boater’s best friend. Fleece is naturally hydrophobic due to the manufacturing process, and will absorb less than .01% of its weight in water. It is an extremely powerful insulator.

Wool – For dry suit layering, wool is a great choice and excellent insulator. One potential issue is that wool is more hydrophilic than polyester microfleece and more likely to absorb sweat. This is also not a good choice for semi-dry gear because it can quickly become waterlogged and cause you to lose body heat. We like that the material is more environmentally friendly and doesn’t release micro-plastics when washed.

Down – Insulating down may seem like an odd choice for the water, but advances in environmentally-friendly feather coatings have improved its ability to retain heat and go longer before wetting out.

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Wicking Materials

Polyester – Polyester under layers have excellent moisture wicking properties. Just be sure of the composition of the layer because many manufacturers use blends of Polyester with Cotton, Lycra, and Spandex.

Polypropylene & Capilene – Many boaters prefer polypropylene and Capilene, over the materials above because they offer slightly better heat retention properties than other base layer materials like polyester.

Nopes of Dry suit Layering

Cotton – Nope, just Nope! Boaters should actively avoid cotton fabrics while on the water. Cotton is non-wicking and keeps moisture close to the skin. In Winter months, this could rapidly induce hypothermia.

Neoprene / Hydroskin – Neoprene is an insulating material designed to keep a thin layer of warm water against your body. Because of that, it is not a good option for wearing under your dry-suit. It is not a breathable material since it has a completely different usage in mind. Avoid any of this type of material including a neoprene blend. The only exception being Neoprene booties over your drysuit are ok.

Lycra and Spandex - Lycra and Spandex are poor materials for heat retention since stretchy materials tend to trap water between the fibers. One consideration for female boaters is that form fitting and supporting Lycra or Spandex garments are slow to dry. These materials are hydrophilic and slow to dry creating a serious risk of skin irritation, rash, and infection because of bacterial growth.

Layering Guide

Unlike many other adventure sports you will always be wearing your outer layer and generally you should always wear your lightweight layer (to avoid chafing). The question is how many more layers should you wear? When layering for dry gear, the most important factor is if you will be wearing a full dry suit or a dry top and paddle pants. The next important factor to consider is expected precipitation, wind chill, air and water temperature. Personal preference is also a factor since some people run hotter or colder.

Dry Top / Paddle Pants Combination

For this combination, there two points for potential failure:

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Waist Band – This is the most likely point of failure for dry tops or paddle pants. If the waist band is loose or moves significantly, you will experience leakage. It is important for the waist band of dry tops or paddle pants to remain secure and close to the body to avoid water intrusion.

Ankles – If your paddle pants include integrated fabric or latex booties, this can present a serious hazard if your waistband fails and the pants fill with water. For that reason, its best to keep a sharp knife on hand. At the same time, if your paddle pants do not include integrated booties, make sure to wear extra layers of footwear. Neoprene booties can become very cold on long days, quickly draining body heat.

Precipitation

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Precipitation, like rain or snow, presents a unique consideration for dry-suit wearing rafters. Unlike whitewater kayakers, rafters do not typically get drenched by each small and medium wave. Because of that, it may be difficult to vent excess heat on days with no precipitation. On trips with rain or snow, the precipitation will continuously drain heat from your dry-suit and body through convection cooling. You may feel warm at the put-in, but precipitation will rapidly lower the temperature of your outer layers. Therefore, if you expect rain or snow, wear heavier insulation than on cold-clear days.

Wind Chill and Air Temperature

Ambient air temperature, cloud cover, and wind speed should also factor into your layering strategy. If there will be no direct sunlight, you will probably want to include an extra layer. The same goes for wind speed, where high winds can rapidly drain body heat. It is important to understand wind chill if you spend time outdoors. Wind chill is a measure of the convective effect of air on your body temperature. To better understand wind chill, the National Oceanic and Atmospheric Administration (NOAA) offers a helpful online calculator. Based on actual temperature and wind speed, their calculator will determine the felt-temperature. For example, if the actual temperature was 40 degrees Fahrenheit with a wind speed of 11 m.p.h., your body will feel and lose heat as if it were 33 degrees Fahrenheit.

Water Temperature

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For rafters, the most powerful heat dissipating force will be water. Depending on local conditions during winter months, river water may actually be warmer than ambient air temperature, especially if it is below freezing outside the water. Most modern river gauges have thermometers built into them, but we recommend carrying a thermometer in your shuttle vehicle. This allows you to check the water temperature at the put-in and reminds you to take extra precautions.

Tips and Best Practices

  • Follow weather forecasts, and conservatively plan your layering for the felt air temperature, which can be determined by comparing the lowest predicted air temperature and expected wind speed. If the water temperature is lower than the estimated felt air temperature, plan for that.

  • If it is raining, add one additional layer to account for heat loss. For example, if it is a warmer day and you planned on wearing only base layers, add an insulating layer when it rains.

  • Wait until your raft is rigged and inflated before donning your dry suit. This will give you time to cool down and not trap sweat inside the dry suit.

  • Bring a dry bag so that you can add or drop layers as conditions require. Having an extra insulating layer in your dry bag will also allow you to adapt to unexpected conditions.

  • Because dry tops and paddle pant combinations are more prone to leaking, avoid down or wool insulation.

  • Avoid using moisture absorbing powders because they can increase moisture retention in key areas and quickly drain body heat.


Deals

If you are looking for base layers to keep warm in your drysuit check out Hiko. They are giving a special 20% off discount to Rafting Magazine readers with the following code: RAFTMAG20

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