Stay Warm In A Dry Suit

How Dry Suits Keep You Warm

The first thing I learned about diving dry was that a dry suit does not necessarily keep you warmer in the water than a wetsuit. Most of the dives my beginning students do are in the 30 to 40 foot (10 to 12 meter) depth range. At these shallow depths, you may not notice that you are any warmer in the water when diving in a dry suit.

Here is why. Depending on the dry suit you select, the suit normally does not keep you warm. Common dry suit material like Trilaminate, vulcanized rubber, coated fabric, and even crushed neoprene suits have little insulating properties. Dry suits made of these materials require the diver to use an undergarment and add air or argon to the suit to stay warm. Undergarments come in various thicknesses like wetsuits, and the diver selects an undergarment for staying warm in a similar way to selecting a wetsuit. The thicker the undergarment, the more protection the diver has from the cold.

Staying Warm Below

The problem with neoprene, of course, is that it is highly compressible. Therefore, the deeper a diver goes, the more the suit compresses and the less effective the suit is at keeping the diver warm. To avoid hypothermia, the diver needs a thicker wetsuit for deeper dives. On the other hand, most dry suit material is non-compressible at depths a diver is likely to go to. After selecting the appropriate undergarment, all the dry suit diver needs to do is add air to the suit during descent to stay warm. More air will need to be added to the suit the deeper the diver goes, but assuming the diver adds air, the insulating properties of the suit and undergarment will stay the same regardless of whether the diver is at 30 feet (10 meters) or 130 feet (40 meters).

The point is, do not expect to be warmer diving in a dry suit if all your dives are at 30 feet (10 meters) or above. A dry suit has the greatest advantage on deeper divers, so divers routinely making deeper dives will certainly find they stay warmer at depth when diving in a dry suit.

Staying Warm Up Top

Getting out of the water is where dry suits also hold a significant advantage. In areas where air temperatures are cool or wind speeds are high, being wet when you get out of the water is very unpleasant. I was on a recent trip to the Bahamas where wind speeds hit 40 knots and air temperatures never climbed past 70°F (20°C). Even though the water was warm, getting out of the water was very unpleasant. Between dives, everyone was cold and miserable. This meant that most divers chilled in the water far sooner because they had lost a great deal of body heat before starting their dives.

Imagine what happens when you get out of the water and you are dry, however! Or when you always get into a suit that is dry! Surface intervals become far more comfortable. You can make more dives in a day because you are not losing heat between dives. Packing up at the end of the day is also no problem. Even when air temperatures dip below freezing, diving becomes doable when a diver is dry before and after the dive. This is a huge advantage that a dry suit has over a wetsuit.