The most commonly used exposure suit is a wetsuit. They are manufactured from closed-cell neoprene foam. Wetsuits are designed to allow a minimal amount of water to enter. The water is then warmed up by body heat.
The following are the main factors impacting warmth.
- Volume of water that flushes through the suit: It is important to have a close fit.
- Thickness of the suit: The thicker the suit, the warmer you will be. But the thicker the suit, the more buoyant and restrictive the suit will be.
- Coverage: The more the body is covered, the warmer the suit will be. A lot of heat is lost through the neck and head. So, a hood can make a big difference to your warmth.
It is important to remember that as the diver descends in the water column, the pressure increases. As a result, the bubbles in the neoprene decrease in size, and the neoprene becomes thinner. This reduces the thermal protection and causes a change in the buoyancy characteristics of the suit. As you ascend, the bubbles will expand. Be sure that you allow for these changes by adding air to your buoyancy control device (BCD) on descent and venting on ascent.