Diving suit

Two divers, one wearing a 1 atmosphere diving suit and the other standard diving dress, preparing to explore the wreck of the RMS Lusitania, 1935

A diving suit is a garment or device designed to protect a diver from the underwater environment. Diving suits made of rubber were first used in World War II by Italian frogmen who found them indispensable in their use. They were made by Pirelli and patented in 1951.^[1]

Modern diving suits can be divided into two kinds:

• "soft" or ambient pressure diving suits - examples are wetsuits, dry suits, semi-dry suits and dive skins
• "hard" or atmospheric pressure diving suits - an armored suit that permits a diver to remain at atmospheric pressure whilst operating at depth where the water pressure is high.

Ambient pressure suits

Diver of the Estonian Home Guard, 1941

There are five main types of ambient pressure diving suits

• dive skins
• wetsuits
• semi-dry suits
• drysuits
• hot water suits

Apart from hot water suits, these types of suit are not exclusively used by divers but are often used for thermal protection by people engaged in other water sports activities such as surfing, sailing, powerboating, windsurfing, kite surfing, waterskiing, caving and swimming.

Ambient pressure suits are a form of exposure protection protecting the wearer from the cold. They also provide some defence from abrasive and sharp objects as well as potentially harmful underwater life. They do not protect divers from the pressure of the surrounding water or resulting barotrauma and decompression sickness.

The suits are often made from Neoprene, heavy-duty fabric coated with rubber, or PVC.

Added buoyancy, created by the volume of the suit, is a side effect of diving suits. Sometimes a weightbelt must be worn to counteract this buoyancy. Some drysuits have controls allowing the suit to be inflated to reduce "squeeze" caused by increasing pressure; they also have vents allowing the excess air to be removed from the suit on ascent.

Standard diving dress, a sixth type of ambient pressure diving suit, is now obsolete but is historically interesting.

Dive skins

Dive skins are used when diving in water temperatures above 25 °C (77 °F). They are made from Spandex or Lycra and provide little thermal protection, but do protect the skin from jellyfish stings, abrasion and sunburn. This kind of suit is also known as a 'Stinger Suit'. Some divers wear a dive skin under a wetsuit, which allows easier donning and (for those who experience skin problems from neoprene) provides additional comfort.

Wetsuits

Main article: Wetsuit

Wetsuits are relatively inexpensive, simple, Neoprene suits that are typically used where the water temperature is between 10 and 25 °C (50 and 77 °F). The foamed neoprene of the suit thermally insulates the wearer.^[2][3] Although water can enter the suit, a tight fitting suit prevents excessive heat loss because little of the water warmed inside the suit escapes from the suit.

Proper fit is critical for warmth. A suit that is too loose will allow too much water to circulate over the diver's skin, robbing body heat. A suit that is too tight is very uncomfortable and can impair circulation at the neck, a very dangerous condition which can cause blackouts. For this reason, many divers choose to have wetsuits custom-tailored instead of buying them "off-the-rack." Many companies offer this service and the cost is often comparable to an off-the-rack suit.

Wetsuits are limited in their ability to provide warmth by two factors: the wearer is still exposed to some amount of water, and the insulating Neoprene can only be made to a certain thickness before it becomes impractical to don and wear. The thickest commercially-available wetsuits are usually 10mm thick. Other common thicknesses are 7mm, 5mm, 3mm, and 1mm. A 1mm suit provides very little warmth and is usually considered a dive skin, rather than a wetsuit.

Semi-dry suits

Semi-dry suits are effectively a thick wetsuit with better-than-usual seals at wrist, neck and ankles. They are used typically where the water temperature is between 10 and 20 °C (50 and 68 °F). The seals limit the volume of water entering and leaving the suit. The wearer gets wet in a semi-dry suit but the water that enters is soon warmed up and does not leave the suit readily, so the wearer remains warm. The trapped layer of water does not add to the suit's insulating ability. Any residual water circulation past the seals still causes heat loss. But semi-dry suits are cheap and simple compared to dry suits. They are made from thick Neoprene, which provides good thermal protection. They lose buoyancy and thermal protection as the trapped gas bubbles in the Neoprene compress at depth. Semi-dry suits can come in various configurations including a single piece or two pieces, made of 'long johns' and a separate 'jacket'. Semi dry suits do not usually include boots, so a separate pair of insulating boots are worn.

Drysuits

Main article: Drysuit

Drysuit in icy water

Drysuits^[4][5][6] are used typically where the water temperature is between -2 and 15 °C (28 and 59 °F). Water is prevented from entering the suit by seals at the neck and wrists; also, the means of getting the suit on and off (typically a zipper) is waterproof. The suit insulates the wearer in one of two main ways: by maintaining pockets of air between the body and the cold water in standard air-containing fabric undergarments beneath the suit (in exactly the way that insulation garments work in air) or via (additional) foamed-neoprene material which contains insulative air, which may be incorporated into the outside of the drysuit itself.

Both fabric and neoprene drysuits have advantages and disadvantages: a fabric drysuit is more adaptable to varying water temperatures because different garments can be layered underneath. However, they are quite bulky and this causes increased drag and swimming effort. Additionally, if a fabric drysuit malfunctions and floods, it loses nearly all of its insulating properties. Neoprene drysuits are comparatively streamlined like wetsuits, but generally do not allow garments to be layered underneath and are thus less adaptable to varying temperatures. An advantage of this design is that even it if floods completely, it essentially becomes a wetsuit and will still provide a degree of insulation.

Special drysuits (typically made of thick rubber) are worn by commercial divers who work in contaminated environments such as sewage or hazardous chemicals. The drysuit is sealed to a diving helmet to prevent any exposure to the hazardous material.

For additional warmth, some drysuit users inflate their suits with argon, an inert gas which has superior thermal insulating properties compared to air.^[7] The argon is carried in a small cylinder, separate from the diver's breathing gas.

Hot water suits

Hot water suits are used in cold water commercial surface supplied diving.^[8] An insulated pipe in the umbilical line, which links the diver to the surface support, carries the hot water from a heater on the surface down to the suit. The diver controls the flow rate of the water from a valve near his waist, allowing him to vary the warmth of the suit in response to changes in environmental conditions and workload. Pipes inside the suit transport the water to the limbs, chest, and back. Special boots, gloves, and hood are worn. The wrists and ankles of the suit are open, allowing water to flush out of the suit as it is replenished with fresh hot water from the surface.

Hot water suits are often employed for extremely deep dives when breathing mixes containing helium are used. Helium conducts heat much more efficiently than air, which means that the diver will lose large quantities of body heat through the lungs when breathing it. This fact compounds the risk of hypothermia already present in the cold temperatures found at these depths. Under these conditions a hot water suit is a matter of survival, not comfort. Just as an emergency backup source of breathing gas is required, a backup water heater is also an essential precaution whenever dive conditions warrant a hot water suit. If the heater fails and a backup unit cannot be immediately brought online, a diver in the coldest conditions can die within minutes.

Diving suit combinations

A "shortie" wetsuit may be worn over a full wetsuit for added warmth. A "skin" may also be worn under a wetsuit. This practice started with divers (of both sexes) wearing women's body tights under a wetsuit for extra warmth and to make donning and removing the wetsuit easier. A "skin" may also be used instead of an undersuit beneath a drysuit in temperatures where a full undersuit is not necessary.

See also

• Timeline of underwater technology
• Space suit
• Standard diving dress
• Atmospheric diving suit

References

1. ^ The first rubber wet suit made by Pirelli and patented in 1951
2. ^ US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006. http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9. Retrieved 2008-04-24. 
3. ^ Fulton, HT; Welham, W; Dwyer, JV; Dobbins, RF (1952). "Preliminary Report on Protection Against Cold Water". US Naval Experimental Diving Unit Technical Report NEDU-RR-5-52. http://archive.rubicon-foundation.org/3387. Retrieved 2008-04-25. 
4. ^ Piantadosi, C. A.; Ball D. J., Nuckols M. L., and Thalmann E. D. (1979). "Manned Evaluation of the NCSC Diver Thermal Protection (DTP) Passive System Prototype". US Naval Experimental Diving Unit Technical Report NEDU-13-79. http://archive.rubicon-foundation.org/3356. Retrieved 2008-05-05. 
5. ^ Brewster, D. F.; Sterba J. A. (1988). "Market Survey of Commercially Available Dry Suits". US Naval Experimental Diving Unit Technical Report NEDU-3-88. http://archive.rubicon-foundation.org/4868. Retrieved 2008-05-05. 
6. ^ Nishi, R. Y. (1989). "Proceedings of the DCIEM Diver Thermal Protection Workshop". Defence and Civil Institute of Environmental Medicine, Toronto, CA DCIEM 92-10. http://archive.rubicon-foundation.org/3922. Retrieved 2008-05-05. 
7. ^ Nuckols ML, Giblo J, Wood-Putnam JL. (September 15-18, 2008). "Thermal Characteristics of Diving Garments When Using Argon as a Suit Inflation Gas.". Proceedings of the Oceans 08 MTS/IEEE Quebec, Canada Meeting (MTS/IEEE). http://archive.rubicon-foundation.org/7962. Retrieved 2009-03-02. 
8. ^ Mekjavić B, Golden FS, Eglin M, Tipton MJ (2001). "Thermal status of saturation divers during operational dives in the North Sea". Undersea Hyperb Med 28 (3): 149–55. PMID 12067151. http://archive.rubicon-foundation.org/2394. Retrieved 2008-05-05. 

External links

• Experimental Dive Suit Flies Navy Divers Where None Have Gone Before - Development of a 1-atmosphere diving suit.
• Scuba America Historical Center - The development of the first wetsuit.
• LA Times: Surfing whodunit - The history of the wetsuit.
• Wetsuit Guide
• Diving Equipment Guide
• ADS database

• History of Diving Museum