Whitewater
Dressing For The Water Rather Than The Air
Paddlers are dressed for immersion, not for the weather on the bank, because a swim in cold water removes function within minutes regardless of how warm the day feels.
The most common clothing error on rivers is dressing for how it feels standing at the get-in. The relevant temperature is the one in the water.
Water removes heat far faster than air
Water conducts heat away from the body at many times the rate of air at the same temperature, so immersion produces a rate of cooling that no amount of layering for air anticipates.
A day that feels pleasant on the bank can involve water cold enough to impair a swimmer within minutes of entering it.
The gap is widest in spring, when air warms rapidly while rivers still carry snowmelt or run cold from reservoir releases.
What cold does to capability
Cold reduces grip strength and fine motor control quickly, and those are exactly what a swimmer needs to hold a throw line or re-enter a boat.
Swimming ability degrades markedly as muscles cool, and a person who could swim to shore when warm may be unable to a few minutes later.
Judgement declines alongside it, often without the person noticing, which is why companions are usually the ones who spot a paddler becoming cold.
Wetsuits and drysuits solve it differently
A wetsuit traps a layer of water against the skin and warms it, which works but leaves the paddler wet and exposed to wind chill between rapids.
A drysuit seals with gaskets and keeps the water out entirely, so insulation comes from what is worn underneath and can be adjusted to conditions.
Drysuits are the usual choice for cold whitewater because the thermal layer stays dry, but they depend on gasket condition and on the zip being fully closed.
The layers underneath do the work
Under a drysuit, insulation comes from synthetic or wool layers that retain warmth when damp, since some moisture from sweat is unavoidable.
Cotton is avoided because it holds water, loses all insulating value when wet and dries slowly, which is a poor combination in this environment.
Extremities need separate attention, since hands on a paddle and a head in the water lose heat quickly and are what fail first.
Dry clothes are part of the trip plan
Groups carry spare insulation in a dry bag, because the person who needs it will be wet, tired and unable to generate much heat themselves.
Where the shuttle is long or the walk out significant, that spare kit is the difference between an inconvenience and a developing emergency.
Recognising and managing hypothermia is covered on wilderness first aid and swiftwater rescue courses, and anyone paddling cold water regularly should hold that training.
