Water temperatures start to drop as we head into fall and winter. While paddling in cooler climes can be a lot of fun, paddlers need to take extra precautions when water temperatures drop to dangerous levels. Cold water shock and hypothermia from cold water immersion rank among the leading causes of injury and death in paddle sports.
Four stages of cold water immersion
Cold water immersion has four stages: cold shock, swim failure, hypothermia, and post-immersion collapse.
Stage one, cold shock, occurs when a boater is unexpectedly thrown into cold water. During this initial shock, a boater may gasp for breath, hyperventilate, or suffer other potentially lethal responses. In this stage, many boaters drown after inhaling water.
Progressing to stage two, swim failure, immersed victims lose manual dexterity, speed of movement, and strength. They cannot self-rescue or assist others in their rescue.
Since water conducts heat away from the body 25 times faster than air, individuals immersed in cold water without adequate protection proceed to stage three, hypothermia. In hypothermia, a drop in the body’s core temperature can lead to loss of consciousness and death. Even after rescue, victims can enter stage four, post-immersion collapse, which can lead to cardiac arrest.
Predicting cold water immersion survival times
Much research has been done on the effects of cold water immersion on the human body. Most experts agree that water temperatures below 70°F put paddlers in danger of cold water immersion and recommend wearing protective garments. Boaters navigating on waters with temperatures below 70°F should take precautions and be prepared for cold water immersion.
Water sports enthusiasts can find many cold water survival charts and graphs online to guide them. As an example, the United States Power Squadrons’ “Hypothermia Survival Times” graphic below clearly demonstrates the danger of cold water immersion: While paddling in 50 to 60°F water, a capsized boater may have less than an hour before encountering serious medical issues.
While these tables provide expected times for succumbing to hypothermia, they don’t account for cold shock, which could become deadly immediately upon immersion. Since body mass varies, use hypothermia tables and graphs as guidelines to help you prepare for a trip on cold water.
Dress for immersion
Wearing proper clothing can increase your working time in the water, which could allow you to be rescued long before the serious effects of cold water immersion set in.
“Dress for immersion” is the rule in paddle sports. Regardless of the air temperature, it’s the water temperature that will kill you, and paddlers must always be prepared to go into the water.
Most outdoor pursuits in inclement weather necessitate three layers of clothing: a base layer, an insulation layer, and an outer layer or shell. The base layer, or first layer next to the skin, should be synthetic such as nylon, polyester, polypropylene, or a similar fabric. Synthetics don’t hold moisture. They shed it away from the skin, causing the fabric to dry quicker with evaporation. In cold and wet weather, avoid wearing cotton. In the outdoors world, it’s said that “cotton kills.” Cotton holds water and dries slowly, causing paddlers to become seriously chilled very quickly. Save cotton for hot summer days when you’re boating on warm water and may want to stay wet longer to keep cool.
Your insulation layer—a synthetic shirt, fleece vest, or top—should be kept dry to help maintain needed body heat. What you choose as your outer layer, usually a water-resistant or waterproof shell, depends on the actual weather conditions. You can find many paddle jackets and dry tops to wear over your base and insulation layers. By repelling wind and spray, your outer layer keeps you dry during rain, heavy seas, or immersion.
As water temperatures drop below 70°F, paddlers should add a neoprene wetsuit either on its own or underneath synthetic clothing. Light wetsuits come in .5 mm, 1 mm and 1.5 mm thicknesses. Heavier wetsuits have thicknesses ranging from 2 mm and up.
Manufacturers provide tables recommending the wetsuit thickness needed for various water temperatures. In general, the colder the water, the thicker the wetsuit. The downside for paddlers is that thicker neoprene restricts movement. Divers can use thicker wetsuits as neoprene compresses underwater facilitating mobility, but for paddlers at sea level, wetsuits won’t compress. Fortunately, many wetsuits made for paddlers use heavier material for the body core and thinner neoprene at the shoulders and arms to increase mobility. For example, a 3/2 wetsuit uses 3 mm neoprene in the body core and 2 mm neoprene in the arms and shoulders.
Popular with paddlers, Farmer John- and Farmer Jane-style wetsuits leave the arms and shoulders free, allowing paddlers to wear a synthetic shirt or fleece top underneath a semi-dry top. Paddlers can also layer wetsuits by wearing a thicker neoprene vest over a thinner full wetsuit top.
Although you can find a wetsuit for use in water temperatures in the 30s, their thickness makes mobility an issue. For this reason, paddlers generally wear drysuits as water temperatures drop into the 40s or 30s. Made of waterproof materials, drysuits have tightly fitting gaskets around the neck and wrists. They also have either ankle gaskets or integrated dry socks as well as waterproof zippers at the entry and other openings. You wear dry clothing underneath and increase the thermal insulation thickness by adding layers, including fleece, as the water temperature decreases.
When it comes to dry tops and drysuits, those made of breathable and waterproof materials such as Gore-Tex, while expensive, are by far the best. Less expensive suits made of non-breathable materials will leave you soaked from perspiration, and waterproof-coated fabric suits deteriorate quickly, making them ineffective and possibly dangerous within several years of use.
Protect your extremities
During cold water immersion, you lose about 50% of body heat from the head, making wearing head, hand and foot coverings important when paddling in cold water. Your life jacket will also help keep your head out of the water after a capsize. To further protect your extremities, consider wearing a fleece beanie, a neoprene hood, boots, mittens, gloves, or anything that will slow heat loss during immersion.
Always much safer than solo paddling, paddling with a group is even more important in cold water. A lone paddler who ends up in cold water has few options. No matter what clothing the paddler wears, his or her cold water survival time is limited without additional protection. In the event of a capsize, a group of rescue-trained paddlers can have a boat dewatered and the paddler back in the boat in about five minutes (see Capsize Recovery, p. 12, The Ensign Spring 2022). If a paddler starts to succumb to the effects of cold water immersion, a group can tow the individual back to safety or contact emergency services for evacuation.
Prior to launch, a paddle group should always consider the possible hazards of any trip. In addition to high winds and rough seas, offshore winds, outflowing current, or a deteriorating weather forecast can increase the risk to dangerous levels, requiring the group to make a “no-go” call.
By following proper precautions, assessing risk, and wearing the proper clothing and safety equipment, paddlers in cold water can enjoy a safe and pleasant experience.
5 Cold Water Precautions
- Always wear a USCG-approved life jacket.
- Always dress for immersion.
- Paddle with other experienced and rescue-trained paddlers.
- Carry a marine VHF radio.
- Perform a group risk assessment before shoving off on a paddle trip.