Skipping Thermal Protection or Selectively Dressing For The Water Temperature.
A majority of the reasons that paddlers give for not dressing for the water temperature invoke some version of the bankrupt “Challenging Conditions” argument originally put forward decades ago by TASK, a trade association of sea kayak manufacturers and others with a financial interest in the growth of the sport. I address it in great detail in Anatomy of A Bad Decision, an article I wrote for Sea Kayaker Magazine in November, 2010. Here's the link:
http://www.coldwatersafety.org/…/Anatomy%20of%20A%20Bad%20D…
Another frequent reason that's given is fear of overheating, which is often expressed something like this: "If we dressed for the water temperature on a hot day, we'd be in danger of geting hyperthermia." *
There’s an easy workaround for the overheating issue, which is to use evaporative cooling to offload excess heat. I personally roll to keep cool and also make sure that my hair is wet and the hat I wear is wet as well. If you can’t roll, you can achieve the same result by splashing water on yourself or using the assised dipping technique mentioned earlier in the thread.
The goal is to maximize the amount of surface area on your clothing that's nice and wet. There are some variations on this depending on the type of thermal protection that you’re wearing, but the underlying concept of evaporation is the same for all of them. If the surface of the neoprene wetsuit or the drysuit fabric doesn't absorb water, wearing a loose, long-sleeved cotton shirt over your wetsuit or drysuit is also a viable way to increase evaporation.
Conversely, if you're wearing a wetsuit and standing on shore during a lunch break on a cool or cold day, particularly when there's a little breeze, you may need to put on something like raingear to cut the convection (windchill) and evaporation so that you don't get chilled. An old paddling jacket or retired drytop also work well in this regard, and it doesn't matter if the jacket has a few smallish holes and the seals are mostly shot. I always carry some large contractor garbage bags to led to fellow paddlers for this purpose.
Learning to work with evaporative cooling takes practice, but it's well worth the effort. Using evaporation to your advantage is a fundamental wilderness travel skill and it's also useful whenever you're working outdoors and concerned about overheating.
*Although the term hyperthermia can refer to any core body temperature above the normal 99.6F, the term is often used synonymously with heat stroke - the most extreme (and generally fatal) heat-related medical problem that one can experience. Heat stroke, however, is characterized by a core temp in excess of 106F.
