Cold Water Gear
The key to surviving cold water is to have the proper gear. Cold water isn't just a phenomenon associated with cold weather. Lake Michigan where I did most of my cold weather paddling doesn't get swimmable until August and starts turning cold again in October. Obviously you don't need quite as much protection when the water is 60 degrees and the air is 80 degrees as you do when the water is 32 degrees and the air is 20 degrees. But extended immersion in 60 degree water can be just as fatal as shorter immersion in water that's just above freezing.
And good judgement is always in order. You don't want to be wearing so much gear that you'll overheat. The question is always whether you can survive the swim to shore. While I wore a dry suit 8 or 9 months out of the year when paddling and rolling in Wisconsin, now that I'm in the San Francisco Bay area, I don't wear my dry suit. I wore it once while surfing my kayak in October and got overheated. Since then, I've switched to a wet suit, and most of the time when paddling in the Bay where there are no waves to speak of, I don't wear cold protection at all.
Here is my outfit, good for paddling in temperatures down to 15 degrees fahrenheit.
Paddling jacket or sprayskirt
In cold weather, I prefer a paddling jacket because it is an extra layer of protection against the wind.
A paddling jacket surrounded by neoprene gloves, boots and hood. The neoprene stuff all hails from a dive shop. Most kayak gear is not made for really cold weather and is maybe good down to 40 degrees F. The stuff from the dive shops is good down to 15 degrees F.
A dry suit is probably the most essential part of your cold weather outfit. It is also the most expensive. You can wear wet suits in moderate weather, but for really cold weather and immersion you will want to get a drysuit. Diveshops sell wetsuits that would be adequate cold water protection, but they make it too hard to move your arms. The drysuit combines protection and mobility. However, for the drysuit to be effective, you will need several layers of clothes underneath. Keep this in mind when buying a drysuit. You can order your drysuit by mail, but ideally, you should try it on in a shop. And when you do, be sure you're wearing at least fleece pants and a fleece sweater to make sure the suit will fit with all the layers you will be wearing. Don't try on a drysuit wearing only shorts and a tee shirt. It is critical that you don't bind in your armpits and are able to move your arms. Drysuits are cut large to acommodate the under-layers you will be wearing, but don't just go by nominal size. If anything binds, move on to the next larger size. Trying the drysuit on is very tiring because you will quickly overheat in the warm store. But be patient. Good fit is essential.
Layers to wear under the dry suit.
Layers under the drysuit should all be modern synthetics that are able to keep you warm even after they get wet. Don't wear cotton. And if you paddle for several hours, you will get wet. High end Goretex dry suits will supposedly breathe, but the non-Gortex dry suits don't breathe and will accumulate perspiration inside the drysuit. Also, after a few years, the ankle, wrist and neck gaskets on drysuits start getting loose, and if you don't replace them right away, some water will seep into your dry suit during immersion.
The trick with layering is to try everything on at the store. As you add layers, you grow in girth, so every layer has to be a little looser than the one before. Some kayaking outfitters sell kayak wear that combines tops and bottoms. These are ideal because when you sit down in a kayak, your pants tend to slide down and your tops tend to ride up, exposing a gap between your top and bottom layers that exposes your skin directly to the cold drysuit. The only problem with these one-piece outfits is that it's much harder to get them to fit both your top and bottom at the same time.
The dry suit and stuff t wear under it. Farthest left, the dry suit. To its right, layer 2, heavy pile pants and sweater. To the right, expedition weight underwear. To the right in yellow, a fleece vest worn over layer 2. Right bottom, gloves, hood and booties.
For extremely cold weather, I wear three layers on top. I start with a heavy weight long-sleeved undershirt. The next layer is a synthetic fleece sweater. And for really cold weather, I add a fleece vest. I suppose the third layer could also be another larger sweater, but by then, you're starting to build up a lot of fabric under your armpits.
I start with heavy weight thermal underwear. Over that I wear fleece sweatpants. I haven't needed a third layer.
I get heavy duty neoprene booties at a dive shop. These usually seal pretty well around the bottoms of the drysuit. They are not waterproof, however. My friend Marty customized his drysuit by buying those lightweight rubber booties that you can buy to fit over your street shoes to protect them from snow and salt. He cut off the ankle gaskets of the dry suit and glued these rubber booties to the bottom of the dry suit. He wears two layers of heavy wool socks on his feet and his feet are always warm.
I use a pair of heavy weight neoprene mittens that I got from a dive shop. At the time I got them, I couldn't get mittens that were warm enough from a paddling shop. These mittens have two drawbacks. The lesser one is that their bulk and slipperiness makes it harder to get a good grip on the paddle shaft. So I keep the shafts of my paddles unvarnished for a secure grip.
The other problem with these mittens is that they're hard to get on and off, and that they make delicate manipulations that require finger control impossible. Once I have these gloves on, all operations have to be on a scale that can be handled by mittens.
I got my hood at a dive shop. It's neoprene and it lets water next to the skin, so the first immersion is always a little bit of a shock, but then I'm comfortable. One thing I found out was that the face is probably the part of the body that's best equipped for immersion in cold water. I'm not sure why, but I suspect that it has better circulation than almost any other part of the body.
For those who don't know, PFD stands for personal floatation device, the thing that was once known as a life vest. I wear the PFD over the drysuit and inside the paddling jacket. When you're sizing the PFD at the store to wear with your drysuit, try it on over a winter jacket. That has about the same bulk as your inner layers and the drysuit. PFD's should not be loose, but take a few deep breaths to make sure that you'll be able to breathe with the PFD on.
Knife and Rope
Theoretically, a knife has nothing to do with cold water paddling, except that the only time I ever wished that I had a knife with me was when I was paddling around ice. Two times I got stuck in front of an ice wall with breaking waves behind me filling the kayak with water as soon as I got out of it. The weight of the water was so great that I couldn't lift the kayak up to the top of the ice wall. And emptying it was beyond my capacity because the breaking waves kept refilling it and standing in chest deep water, I didn't have the leverage to hold it so the water could slowly drain out of the cockpit. I could get one end of the boat up on the ice but I couldn't lift the end full of water. Had I had a knife on me, I could have slit the deck near the end of the boat and the water would have run out, allowing me to lift the boat up on the ice. But I didn't have a knife. The first time, firemen showed up and put ropes on my kayak and pulled it up on the ice. The second time I barely got myself up on the ice and left the kayak in the water. Unfortunately the wind was blowing offshore and the kayak headed toward the horizon without me. A rope might have helped too, at least I could have secured the boat til I could find someone to help me drag it up on the ice.