As the water temperature drops below 55, there is a very noticeable difference in the onset effects of "cold shock" (see Cold Water Safety article). In the 45 to 35 degree range, the differences are dramatic and dangerous unless you are completely protected.

Everything seems more sluggish. Your boat will feel as though it has been trapped by wet towels and your paddle will simply fail to find that spot that will allow you to roll up. Note that the temperature of sea water can actually get below 32, which is the freezing point of pure water. When you see ice everywhere, it's easy to find yourself in below-32 degree water.

In this range it's extremely important to take into account that wind-chill will be freezing all the water on the outer surface of your drysuit - and all the water inside your dry suite as well unless you have an excellent wicking and insulating layering system in place. This freezing will happen as you paddle, but will be more pronounced when you are not active (when sitting in the boat, or coming ashore). In these conditions it is extremely important to have excellent protection about your neck and other exposed areas as well to avoid "cold shock" on first immersion. It is crucial to stay rational as you paddle.