Two words: neoprene and polypropylene. Get to know these fabrics intimately-- literally. Polypropylene (you’ll hear us call it "polypro") is a fabric that’s been made into underpants, long johns, shirts, socks-- you name it. And thank goodness, because this lovely fabric helps retain body heat even when wet.
Neoprene, on the other hand, really only begins to work when it becomes wet. When water hits neoprene, it gets absorbed into tiny cells in the fabric which then warm up with your own body heat. That’s why wetsuits actually keep you warmer when they’re wet.
Another great material is fleece. Fleece, made from plastic, could be called the modern wool. The biggest bonus is that it’s lighter and way less itchy than wool. A fleece pullover is a great addition to your wetsuit get-up. Wear it over your wetsuit and under your splash jacket.
Speaking of splash jackets, use one on your next trip and you won’t be disappointed. If it’s windy, your splash jacket will act as a windbreaker. When you burst through huge waves, the splash jacket will decrease the initial cold shock of those waves hitting your body. Of course, if you are the proud owner of a dry top (a beefier splash jacket with rubber gaskets at the wrists and neck), you’ll fair even better.
Last but definitely not least we’ve got to cover those extremities. Studies show that we lose up to fifty percent of our body heat from our heads. Covering your noggin is of the utmost importance. If you’re rafting a Class IV river, you’ll be required to wear a helmet and this will help dramatically in your quest to keep warm. Better yet, wear a fleece or polypro skullcap to keep the heat in. A wool hat will do too, if you can stand being a bit itchy. Just make sure not to wear a cotton baseball cap. When wet, cotton is the devil’s fabric. Wet cotton robs your body of heat. Unless it’s 100 degrees out, never wear cotton on the river. No cotton. Ever. No way.
Also of great importance is covering the little piggies-- your feet and toes. Neoprene booties may feel less than fashionable but at least your toes will be toasty. Wool socks will also work but when wet they tend to feel heavy, lending to that leaden foot feeling which can be a definite downer when swimming.
As for keeping your hands warm, you’d be hard pressed to find a guide who wears gloves while rafting. Gloves tend to be too bulky and can impair your ability to grasp things, namely your paddle. Better to go bare handed and just suck it up.
Now that you think you've got to go buy out REI's stock of cold weather gear, here's another piece of advice: don’t wear too many layers. A large part of staying warm is healthy blood circulation (this is why your guide will often make you paddle through calm stretches of river on cold days--it keeps your blood pumping). If you yank on too many layers, you run the risk of cutting off your circulation ever so slightly (ever worn three pairs of socks while skiing and your feet still felt icy cold?). Also, too many layers can make it hard for you to move your limbs which could spell trouble if you go for a swim.
Lastly, adequate hydration has a huge effect on your ability to stay warm. Being dehydrated compromises your body's regulatory system, making it harder for your body to concentrate on temperature stabilization. On the morning of your rafting trip, make sure you drink plenty of water and go easy on the coffee (caffeine dehydrates). And when your guide passes the water bottle around, make sure you take healthy swigs every time.
In summary, don the wetsuit, polypro or fleece shirt, splash jacket, booties and a hat and you’re ready to take on the rapids. Keep paddling and drink lots of water and you’ll be one toasty paddler.