page_title: Dry suit
section_title: Early years
hierarchical_section_title: Dry suit / History / Early years
caption_attribution_description: A British navy frogman, here equiped with the well known Davis apparatus. Those men were the underwater experts who blasted a hole in the Nazi's Atlantic Wall to enable invasion craft to reach the Normandy beaches on D-Day.
context_page_description: A dry suit or drysuit provides the wearer with environmental protection by way of thermal insulation and exclusion of water, and is worn by divers, boaters, water sports enthusiasts, and others who work or play in or near cold or contaminated water. A dry suit normally protects the whole body except the head, hands, and possibly the feet. In hazmat configurations, however, all of these are covered as well.
  The main difference between dry suits and wetsuits is that dry suits are designed to prevent water from entering. This generally allows better insulation making them more suitable for use in cold water. Dry suits can be uncomfortably hot in warm or hot air, and are typically more expensive and more complex to don. For divers, they add some degree of operational complexity as the suit must be inflated and deflated with changes in depth in order to minimize "squeeze" on descent or uncontrolled rapid ascent due to excessive buoyancy.
  Dry suits provide passive thermal protection: They insulate against heat transfer to the environment.
context_section_description: In the 1830s the Deane brothers asked Augustus Siebe to improve their underwater helmet design. Expanding on improvements already made by another engineer, George Edwards, Siebe produced his own design; a helmet clamped to a full length watertight canvas diving suit. The real success of the equipment was a valve in the helmet that meant that it could not flood no matter how the diver moved.
  Siebe introduced various modifications on his diving dress design to accommodate the requirements of the salvage team on the wreck of HMS Royal George, including making the helmet be detachable from the corselet; his improved design gave rise to the typical standard diving dress which revolutionised underwater civil engineering, underwater salvage, commercial diving and naval diving.
  In France in the 1860s, Rouquayrol and Denayrouze developed a single stage demand regulator with a small low pressure reservoir, to make more economical use of surface supplied air pumped by manpower. This was originally used without any form of mask or helmet, but vision was poor, and the "pig-snout" copper mask was developed in 1866 to provide a clearer view through a glass faceplate on a copper mask clamped to the neck opening of the suit. This was soon improved to become a three-bolt helmet supported by a corselet (1867). Later versions were fitted for free-flow air supply.
  These dry suits were directly coupled to the air space in the helmet, and buoyancy was not sufficiently controllable to allow swimming - the diver needed to remain upright when descending or ascending to allow venting of excess air through the helmet exhaust valve, or risk a potentially fatal blowup.(ref usn training film - see Standard diving dress) With these suits the diver would be weighted sufficiently to allow reasonably stable walking on the bottom, and would either be pulled up and lowered by the tenders, or would slide down the shotline and climb back up it. Great care would be taken in normal diving to avoid over-inflation of the suit underwater as this could lead to a runaway ascent.
  The earliest suits were made of waterproofed canvas invented by Charles Mackintosh. From the late 1800s and throughout most of the 20th century, most suits consisted of a solid sheet of rubber between layers of tan twill. Their thick vulcanized rubber collar is clamped to the corselet making the joint waterproof. The inner collar (bib) was made of the same material as the suit and pulled up inside the corselet and around the diver's neck. The space between the bib and corselet would trap most condensation and minor leakage in the helmet, keeping the diver dry. The sleeves could be fitted with integral gloves or rubber wrist seals and the suit legs ended in integral socks.
  The twill was available in heavy, medium, and light grades, with the heavy having the best resistance to abrasion and puncture against rough surfaces like barnacles, rocks and the jagged edges of wreckage. Vulnerable areas were reinforced by extra layers of fabric. Different types of dress are defined by the clamping of the collar seal to the rim of the corselet or to the joint between bonnet and corselet, and the number of bolts used for this purpose. The legs may be laced at the back to limit inflated volume, which could prevent excess gas from getting trapped in the legs and dragging an inverted diver to the surface. In normal UK commercial diving activities, the legs often did not have the lace up option.
  The rubberised fabric was waterproof, as was the seal to the helmet and the cuff seals, so the diver remains dry – a big advantage during long dives – and wears sufficient clothing under the suit to keep warm depending on the water temperature and expected level of exertion. The suit was usually a very baggy fit on the diver, and if over-inflated, would be too bulky to allow the diver to reach the control valves for air supply and exhaust. This contributed to the risk of suit blowup, which could cause an uncontrollable buoyant ascent, with high risk of decompression illness. To add to this problem, a runaway ascent cou
caption: British navy frogman in dry suit c1945
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