Water temperature is one of the biggest concerns for those preparing to dive in cold waters. For many people, just the sight of divers in cold water is enough to bring chills through their spines! But even if you only plan only diving the warm waters of the tropics, heat loss is a real threat unless you wear an appropriate suit to retain your body heat.
Fortunately, many styles of exposure suits are available to keep you safe and warm no matter what the temperature is. In this lesson, you'll learn why divers need to wear exposure suits, the different options available, and how to care for your suit.
Why Divers Wear Exposure Suits
Warmth is one of the major factors contributing to a diver's enjoyment. Amazing visibility or an abundance of marine life will go unnoticed if you're in a hurry to exit the water to get warm.
Warmth is also a major safety factor. Heat is conducted from our skin whenever we are in an environment cooler than our skin temperature. This rarely presents problems for us on land because our bodies can produce heat fast enough to maintain our core body temperature. However, water conducts heat from our bodies 25 times faster than air. This means that without thermal protection, our bodies can chill in any water that's cooler than our skin temperature.
Selecting an Exposure Suit
The primary purpose of an exposure suit is to keep a diver warm, so water temperature is the primary factor to consider when selecting a suit. Fortunately for us, appropriate exposure suits are available for any water temperature.
Other factors must be considered as well. For example, you'll get colder if you stay still for long periods of time, so if you plan on participating in slow-moving dive activities you may want a warmer suit. Or perhaps you're more sensitive than others and desire more insulation.
While there are many styles and brands available, most suits can be placed in one of three categories. These are skin suits, wetsuits, and dry suits.
Some dive locations are so warm that thermal protection isn't required. However, exposure suits offer several other benefits as well. They help prevent sunburn, protect your skin from stings, and in some cases, protect the skin against cuts and scrapes.
Skin suits are constructed from thin materials such as nylon and thin neoprene rubber. They provide little to no thermal protection, but are very effective at protecting your skin. For this reason, they are appropriate when the water temperature doesn't require thermal protection but you still want to wear skin protection.
Wetsuits are the most popular form of exposure protection because of their low cost, available styles, and ease of use. Chances are, you'll be wearing one during your confined and open water sessions.
Wetsuits are constructed of a foam rubber called neoprene. The gas bubbles inside the neoprene trap your body heat and warm the water that enters the suit. This material is also extremely flexible, which is necessary for freedom of movement.
Most wetsuits are lined with nylon on both sides of the neoprene. The nylon helps protect the neoprene from tears and cuts. It also allows the suit to slide over your skin with ease, making it easier to don and doff the suit.
Sizing A Wetsuit
Wetsuits keep you warm by trapping a thin layer of water between the suit and your skin. Your body heat then heats this water. If the suit fits properly, that water will remain in your suit during your dive and you'll remain warm. However, if too much water flows into the suit your body will continue to heat to the water in the suit. This can result in chilling.
For this reason, it's important to select a suit that fits properly. The fit should be snug enough to trap a thin layer of water between your skin and the suit. But comfort is also crucial. You must have freedom of movement to swim and manipulate your gear. Additionally, a suit that's too tight will make breathing difficult.
The wetsuit you select will depend on the conditions you'll be diving in. When making your selection, consult a local dive shop, instructor, or experienced diver for their suggestions and opinions.
Wetsuit styles are available for most conditions. If you only plan on diving in warm water, a shorty wetsuit may be appropriate. These suits are cut above the knees and elbows, allowing complete freedom of movement for your legs and arms.
Full suits are the most common style. These suits cover the entire body, so in addition to the torso, they provide warmth and skin protection for the arms and legs.
Our bodies lose a significant amount of heat through the torso and head, so when diving in cold water, a 2-piece suit is often desirable. These suits consist of overalls and a jacket. This combination doubles the coverage around the diver's upper body, which results in increased thermal protection.
Wetsuits are available in a range of thicknesses. The thicker the neoprene, the warmer the suit will be. For this reason, it's important to make sure you wear enough to keep you warm, but not enough to cause overheating. The most common thicknesses are 3-mm, 5-mm, and 7-mm. 3 and 5-mm suits are popular for warm water diving, while those in cold water usually prefer a 7-mm suit.
Depth and Wetsuit Compression
In the "Physics" chapter, you'll learn that air spaces compress as you descend in the water. This affects the small gas bubbles in neoprene, and as these bubbles compress, the neoprene becomes thinner. As a result, wetsuits provide less thermal protection as you dive deeper. Fortunately, the suit expands back to its original thickness as you ascend to the surface.
Some of the compressed gas bubbles do not return to their original size. With every dive, a small number become weak and break down. While you won't notice a change in your suit from one dive to the next, after a few hundred dives, a significant percentage of these bubbles may be damaged. At this point, the suit is considered to be "crushed," and needs to be replaced.
Dry suits are the warmest exposure suit available for recreational diving, and are popular with many cold water divers. These suits use watertight wrist and neck seals to prevent water from entering the suit, and a special water and airtight zipper seals the suit's entry.
Most dry suits are made of a laminate of rubber and nylon, and are called shell suits. This material is thin and lightweight, but provides no thermal protection. To keep the diver warm, the shell must be worn with special thermal garments made of fleece or other warm synthetic materials. The advantage of this system is the ability to add or remove layers of thermal garments according to water temperature.
Another popular style is the neoprene dry suit. These suits are made of insulating neoprene similar to a wetsuit, and do not require additional thermal garments. However, because neoprene compresses at depth, some divers choose to wear additional thermal garments to prevent chilling at depth.
Using A Dry Suit
Dry suits retain an air space around the diver's body. Because air compresses at depth, additional air must be added to the suit to prevent the suit from squeezing the diver during descent. This is accomplished by using an inflation valve that fills the suit with air from the scuba cylinder.
The air inside a dry suit expands during ascent. If this expanding air is not vented, the diver will become more buoyant and an uncontrolled ascent results. For this reason, dry suits must have an exhaust valve to allow excess air to be vented. This valve is usually mounted on the left arm, and automatically vents air when the left arm is raised.
You should attend a dry suit specialty course if you plan to purchase or rent a dry suit. The course will teach you how to control the air space inside the suit, which is essential for your safety. You'll also learn how to take care of the dry suit, which is important for preventing failures that could result in a flooded suit.
Your body loses a significant amount of heat through your head, so a hood is required when diving in cold water. Hoods are made of the same neoprene used to manufacture wetsuits, and are available in several styles.
Most hoods have an attached bib that you tuck underneath your wetsuit. This helps protect your neck from the cold water, and also reduces water flow into the wetsuit.
If you also require additional torso insulation you may want to wear a hooded vest. Most hooded vests are designed to be worn underneath a wetsuit, and are popular with cold water divers who wear single-piece wetsuits.
When selecting a hood, choose one that's snug but comfortable. Avoid hoods that are uncomfortable, restrict blood circulation, make breathing difficult, or prevent neck movement.
Booties keep your feet warm while diving in cold water. They also provide traction on slippery surfaces and protect your feet from sharp objects and hot surfaces. Additionally, they are usually required when wearing heel strap fins because they prevent blisters and allow the foot to fit the fin's pocket properly. For these reasons, booties are recommended regardless of water temperature.
Booties are available in many sizes and styles, but most share some common features. Most are constructed of neoprene, which provides thermal protection. A rubber sole provides traction on slippery surfaces. A side zipper is a popular feature that allows ease of entry and a snug fit. Many booties have rubber heels and toes to protect them from premature wear from a fin pocket or strap.
Dive gloves are constructed of a variety of materials including neoprene, nylon, leather, or cotton.
Neoprene gloves are a must for cold water diving because chilled hands may become numb or immobile. Another benefit is cut and scrape protection, so divers in warm water may choose to wear gloves as well.
Gloves must fit the hand and fingers closely, but not restrict movement of the fingers. Test the fit of several brands and sizes, and select the best fit possible.
Unfortunately, divers are more likely to touch marine life when wearing gloves. This can injure or kill many organisms, and damage delicate reefs. For these reasons, gloves are not permitted in many warm water destinations throughout the world.
Exposure Suit Maintenance
Like all diving equipment, your exposure suit needs to be rinsed with fresh water at the end of the day. Commercial detergents are also available to use on occasion when thorough cleaning is necessary.
Neoprene is similar to bubble wrap. When hard pressure is applied to a small area, the gas bubbles crush, and this sacrifices the insulating qualities of the suit. For this reason, dry and store your suit on a wide hanger to protect the shoulders from creases, and avoid folding the suit for storage.
Wetsuits should be hung inside-out while drying. This allows the inside of the suit to dry first, which is especially important during multiple days of diving.
Like all diving equipment, hang your suit away from direct sunlight and store in a cool, dry place.