Extend your Diving Season!

If you venture down to your favorite shore diving sites outside of the summer months you’re still bound to see divers entering the water. The chances are high that those divers are wearing a type of exposure protection that’s extremely popular with seasoned New England divers, the Drysuit!

Drysuit Components

Drysuits are waterproof exposure suits that include the following components:

  • Neck and wrist seals (to keep water out!)
  • Intake and Exhaust valves (to maintain the volume of gas in your suit)
  • Undergarments (to keep you warm)
  • Optional Active Heating accessories (to keep you warmer for longer)

This article will take you through these components and introduce you to some drysuit materials. For more in-depth information and in-water training so that you can safely dive dry, check out the ECD Drysuit Diving class!

Keeping the water out to stay warm!

Wetsuits use three basic elements to keep divers warm. First, the neoprene is warmer when it is thicker and higher quality. There may be additional layers of material that add to the neoprene insulation making it more efficient. Second, the water that enters the suit is warmed by the heat your body radiates; some of this heat is retained in the water. Third, the seals on the neck, wrists, and ankles prevent cold water from moving into the suit and warmed water from moving out. Effective seals are what make a semi-dry wetsuit warmer. Drysuits take this concept to the next level using tight-fitting neck and wrist seals that are designed to prevent any water from entering the suit. This way, instead of water, air can be used as an insulating layer which is significantly more efficient than water. Think of a double-wall insulated thermos or cooler. You can keep beverages hot and ice cold for hours or days in a well-sealed, air-insulated container.

Intake and Exhaust

Since drysuits take advantage of gas as an insulator and Boyle’s Law dictates that a gas volume decreases with increased pressure (at a constant temperature), we must add gas to the suit as we descend or it will be compressed leaving you cold and uncomfortable. For that, we use an intake valve on the chest:

As we begin to return to the surface, the pressure on the insulating gas in our suits will decrease so it will begin to expand. To vent the gas, we use an adjustable exhaust valve which is typically positioned on the left shoulder.

The intake and exhaust allow a diver to get a suit lofted with enough gas to be comfortable throughout the dive.

Drysuit Undergarments

A drysuit is a highly versatile platform. It offers the cold water diver an opportunity to adjust the thickness and insulating properties of the suit simply by changing out which layers (undergarments) are worn inside! During the summer, a drysuit can be worn over a lightweight undergarment. A fleece suit, like the Fourth Element Arctic, will keep you toasty warm for hours in 60-degree water. In winter months, you can dive comfortably in a heavier undergarment like the Halo 3D, with a base layer and vest. The thickness of the layers will determine the volume of the gas in the suit and impact proportionally how much extra weight a diver will require to get neutrally buoyant.

Fourth Element Undergarment Selector

Chose the right undergarment for the water temperature of your upcoming dive!

Check out this article from our friends at Fourth Element on how to select the right undergarment layers for your next dive!

Active Heating

Traditional layering of undergarments may be insufficient for some divers. For example, local divers who get cold quickly in the summer may not be able to tolerate winter temperatures. Additionally, technical divers who may be fine during the active phase of a deep dive may get chilly during a decompression stop increasing the risk of decompression sickness (DCS). These divers often opt for a drysuit with active heating. Active heating will convert battery power to heat. Some systems are adjustable and can be turned up at the end of a dive to provide extra comfort when you need it most! This involves using a securely housed battery and interfaces such as the Light Monkey Dual-outlet Heater Valve or Santi Thermovalve and connects to undergarments with built-in heating systems like the Gloves, Vest, Flex 2.0 or BZ400 from Santi, Lightmonkey Heater Base Top, or Scubaforce X-Heat jumpsuit. Recreational divers who want to reduce their required ballast can reduce the thickness of their undergarments by adding active heating. Alternatively, for those who are not ready to invest in active heating, passive heat retention layers, like the Fourth Element X-Core Vest, may prove a good alternative.

Dry Gloves

Drysuit divers often find that the single limiting factor in cold water diving is the comfort of their hands. Wet gloves are neither comfortable or very warm, so when you get comfortable diving in your new drysuit the first accessory to explore is a dry glove system. The Thenar Dry Glove system from Scuba Force is easily installed on almost any drysuit system and offers a great combination of ergonomics, durability, and price. Like other undergarments, various materials and thicknesses can be used for glove liners that can be swapped out for different occasions.


Drysuit Materials

The original drysuits were made of stiff and heavy vulcanized rubber material. These are still used by some divers in industrial or public safety settings due to their durability. Most drysuits used in recreational and technical diving are now composed of either trilaminate or neoprene.

Trilaminate is a three-layer material that is typically composed of a durable outer layer such as ballistic nylon, a waterproof butyl rubber middle layer, and a smooth inner layer like polyester. The combination results in a lightweight suit that can be quite versatile. It often is coupled with a self-donning front zipper and a telescoping torso that allows you to comfortably get in and out of the suit and then adjust it down to size without the aid of another diver. Most suits come with glued in latex neck and wrist seals that require professional servicing when damaged. The Swedish firm SiTech developed wrist and neck seal systems that use gaskets to support diver-replaceable seals in the more comfortable silicone material. Several product generations in, replaceable seals are a popular add-on since seal failure could make the end of a trip. Trilaminate suits range in price based on factors like material selection, build quality, and custom fitting.

Neoprene used in drysuits is similar to the waterproof foamed rubber used in wetsuits. However, unlike wetsuit neoprene, most drysuit neoprene is either “compressed” or “crushed” which helps to increase durability and reduce the thickness of the suit. These neoprene suits tend to offer more native insulation than a trilaminate but the material is bulkier. They tend to be “shoulder entry” with a zipper going from shoulder to shoulder behind the neck seal. This type of entry requires a dive teammate to zip you in and out of the suit. Neoprene suits also tend to come with relatively durable and comfortable neoprene wrist and neck seals which must be replaced by a qualified shop when they stretch out or are damaged.

ECD offers a comprehensive drysuit training program, drysuit rental packages, and rent-to-own options for divers looking to get into a premium trilaminate drysuit like the Santi E.Lite Plus or Fourth Element Argonaut.