Standard diving dress

Diver in standard diving dress

A standard diving dress consists of a metallic (copper and brass or bronze) diving helmet, an airline or hose from a surface supplied diving air pump, a canvas diving suit, diving knife and weighted boots.[1] An important part of the equipment is the lead weights, generally on the chest, back and shoes, to counteract the buoyancy of the helmet and diving suit.

This type of diving equipment is also known as hard-hat or copper hat equipment, or heavy gear. Leading british manufacturers were Siebe Gorman and Heinke. In the United States, the dominant makers were DESCO, Morse, Miller-Dunn and Schräder and it is sometimes known as a "Diver Dan" outfit, from the television show of the same name. It was commonly used for underwater civil engineering, commercial diving, pearl shell diving and naval diving.

History

Early history

In 1405, Konrad Kyeser describes a diving dress made of a leather jacket and metal helmet with two glass windows. The jacket and helmet were lined by sponge to "retain the air" and a leather pipe was connected to a bag of air.[2]:693 A diving suit design was illustrated in a book by Vegetius in 1511.[2]:554

Borelli designed diving equipment that consisted of a metal helmet, a pipe to "regenerate" air, a leather suit, and a means of controlling the diver's buoyancy.[2]:556 In 1690, Thames Divers, a short lived London diving company, gave public demonstrations of a Vegetius type shallow water diving dress.[2]:557 Klingert designed a full diving dress in 1797. This design consisted of a large metal helmet and similarly large metal belt connected by leather jacket and pants.[2]:560

Modern era

1842 sketch of the Deane brothers' diving helmet, the first surface-supplied diving dress equipment in the world.

The first successful diving helmets were produced by the brothers Charles and John Deane in the 1820s.[3] Inspired by a fire accident he witnessed in a stable in England,[4] he designed and patented a "Smoke Helmet" to be used by firemen in smoke-filled areas in 1823. The apparatus comprised a copper helmet with an attached flexible collar and garment. A long leather hose attached to the rear of the helmet was to be used to supply air - the original concept being that it would be pumped using a double bellows. A short pipe allowed breathed air to escape. The garment was constructed from leather or airtight cloth, secured by straps.[5]

The brothers had insufficient funds to build the equipment themselves, so they sold the patent to their employer, Edward Barnard. It was not until 1827 that the first smoke helmets were built, by German-born British engineer Augustus Siebe. In 1828 they decided to find another application for their device and converted it into a diving helmet. They marketed the helmet with a loosely attached "diving suit" so that a diver could perform salvage work but only in a full vertical position, otherwise water entered the suit.

Siebe's improved design in 1873, from the Illustrated London News. The helmet's basic features can be seen: A helmet, supplied with air from the surface, and a waterproof suit. The helmet is screwed onto the suit with wingnuts, which can be seen being tightened by one of the support crew on the left of the picture.

In 1829 the Deane brothers sailed from Whitstable for trials of their new underwater apparatus, establishing the diving industry in the town. In 1834 Charles used his diving helmet and suit in a successful attempt on the wreck of Royal George at Spithead, during which he recovered 28 of the ship's cannon. In 1836, John Deane recovered from the discovered Mary Rose shipwreck timbers, guns, longbows, and other items.

By 1836 the Deane brothers had produced the world's first diving manual, Method of Using Deane's Patent Diving Apparatus which explained in detail the workings of the apparatus and pump, plus safety precautions.

In the 1830s the Deane brothers asked Siebe to apply his skill to improve their underwater helmet design.[6] Expanding on improvements already made by another engineer, George Edwards, Siebe produced his own design; a helmet fitted 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. This resulted in safer and more efficient underwater work.

Siebe introduced various modifications on his diving dress design to accommodate the requirements of the salvage team on the wreck of the 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.[6]

Today

Modern diving helmets are made of stainless steel, fiberglass, or other strong and lightweight material. The copper helmets and standard diving dress are still widely used in poorer parts of the world, but have largely been superseded by lighter and more comfortable equipment.

General description

Manual air pump for Standard diving equipment
View into the box of a manual air pump

Standard diving dress can be used up to depths of 600 feet (180 m) of sea water, provided a suitable breathing gas mixture is used. Air or other breathing gas may be supplied from hand pumps, compressors, or banks of high pressure storage cylinders, generally through a hose from the surface, though some models are autonomous, with built-in rebreathers or compressed gas supplies.

A diving helmet may be described by the number of bolts which hold it to the suit or to the corselet, and the number of vision ports, known as lights. For example a helmet with four vision ports, and twelve studs securing the dress, would be known as a "four light, twelve bolt helmet".

When the telephone was invented, it was applied to the standard diving dress. The helmet diver remains dry - a big advantage during long dives.

In the diving helmet, a principle similar to that of the wet diving bell is used, where compressed air is provided to the helmet.[1] The air lets the diver breathe normally and equalizes his internal pressure with the water pressure outside. The helmet must have a non-return valve at the rear air input port of the helmet, to prevent massive and fatal squeeze, should the air line be cut at the surface. Diving helmets, while very heavy, displace a great deal of water and combined with the air in the dress, would make the diver float with his head out of the water.[2]:33 To overcome this, some helmets are weighted, while other divers wear weighted belts which have straps that go over the base of the helmet. The diver may have an air inlet control valve, while others may have only one control, the exhaust. Helmet divers are subject to the same pressure limitations as other divers, such as decompression sickness and nitrogen narcosis.[2]:1

A full diving dress can weigh over 80 kilos.

Suit

The one piece diving suit is called a diver's dress. The earliest suits were made of waterproofed canvas invented by Charles Mackintosh. From the late 1800s and throughout most of the 20th century, most Standard Dresses 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 dress and pulled up inside the corselet and around the diver's neck. The wrist cuffs are also made of vulcanized rubber.

The twill was available as heavy, medium, and light with the heavy working best against rough surfaces like barnacles and rocks. Different types of dress are defined by the clamping of the outer collar clamps to the corselet. The legs may be laced to prevent gas from getting trapped in the legs and dragging an inverted diver to the surface.[2]:56 In normal UK commercial standard dress diving activities, the dress often did not have the lace up option.

Helmet

Copper diving helmet with threaded connection to corselet

The helmet was usually made of copper with soldered on brass fittings. The windows are known as lights or ports. The front port usually opens on the surface by being screwed out or opens a hinge. The back of the helmet has two goose neck fittings. One has a non-return valve and is the connection for the air line. The other is for the diver's telephone.

Later helmets include a non-return valve where the airline is connected, which prevents potentially fatal helmet squeeze if the pressure in the hose is lost. The difference in pressure between the surface and the diver can be so great that if the air line were cut on the surface and there was no non-return valve, the diver would be squeezed into the helmet by the external pressure, and injured or possibly killed.

Helmets have a spring-loaded exhaust valve which allows the air to leave the helmet. The spring force is adjustable by the diver and prevents the diver's suit from deflating completely or over-inflating and the diver being floated uncontrollably to the surface. Some helmets have an extra manual exhaust valve known as a spit-cock. This allows the diver to vent excess air when he is in a position where the main exhaust will not function correctly.

Corselet

Corselet showing interrupted thread for helmet connection and straps clamping it to the suit

The corselet (also known as a breastplate) is an oval copper and brass collar-piece resting on the top middle parts of the shoulders, chest and back, to support the helmet and seal it to the suit. Most helmets are joined to the corselet by 1/8th turn interrupted thread. The helmet is placed on the breastplate facing the divers left front and then turned forward, seating on a leather gasket. The helmet usually has a safety lock which prevents it from rotating back and thus separating underwater. However, other styles of connection were used and the joins may be by clamp or bolts. Some helmets and breast plates are one piece and secured to the suit in other ways.

The breast plate is usually joined to the diving suit by having the holes in the collar placed over bolts on the breastplate, and then being made water tight by compressing brass rails (also known as brailes or brass straps) against the collar with wing nuts.

Weighted shoes

Weighted shoes

The helmet divers used heavily weighted shoes to steady them on the sea floor. The weighted sole is bolted to a wooden insole, which in turn has a leather, canvas or rubber upper. Lead was the most common sole and a pair could weigh up to 34 lb. Brass soled shoes with canvas uppers were introduced in WWII and are still in use. Some early brass shoes were called sandals because they were a casting held to the diver's feet by simple straps. Japanese divers often used iron soled shoes. The diver tends to lean forward against the drag of the water when walking on the bottom, and could often not see where he was putting his feet, so the toes are capped, usually with brass.

Diver's knife

A diver's knife from three bolt equipment

The diver's knife is a tool, not a weapon. It is not used to fight sea life. The diver can pry and hammer with it. It usually has one side of the blade serrated to cut heavy lines such as rope, and a sharper side for fine lines such as monofilament fishing line. There are two general knife sheaths; one is flat with a spring retention and the other is tube-shaped and has an ajax triple thread, allowing the diver to insert the knife in it from any direction. He then rotates the knife, thereby engaging the threads and locking the knife into the sheath.

Diver's weights

There are two general weight types. Both are still in use. The older helmet weights are used in pairs. The large horse shoe type weights hold the helmet down and are attached to the corselet with figure eight hooks that go over breast plate weight studs. The Greek sponge divers simply joined the weights with ropes which went over the corselet like saddle bags. The second weight type is the weight belt. It has shoulder straps which cross at the back and go over the breast plate. The US Navy Mk V weight belt weighed 83 lb. However, commercial belts usually were about 50 lb.

Air control valve

Most divers have an air control valve which is a lot like a common water tap. Air which is sent down the air hose can be controlled by the diver. The early helmets, like those by Siebe Gorman did not have air control valves and the diver signaled the surface with pulls on his rope or air line, indicating that he needed more or less air.

See also

References

  1. 1 2 Stillson, GD (1915). "Report in Deep Diving Tests.". US Bureau of Construction and Repair, Navy Department. Technical Report. Retrieved 2008-08-08.
  2. 1 2 3 4 5 6 7 8 Davis, RH (1955). Deep Diving and Submarine Operations (6th ed.). Tolworth, Surbiton, Surrey: Siebe Gorman & Company Ltd.
  3. ↑ The Infernal Diver by John Bevan, Hardcover - 314 pages (27 May 1996), Submex Ltd; ISBN 0-9508242-1-6
  4. ↑ http://scubaeds.com/10.html Scuba Ed's - History of scuba diving
  5. ↑ Newton, William; Partington, Charles Frederick (1825). "Charles Anthony Deane - 1823 patent". Newton's London Journal of Arts and Sciences (W. Newton) 9: 341.
  6. 1 2 Acott, C. (1999). "JS Haldane, JBS Haldane, L Hill, and A Siebe: A brief resume of their lives.". South Pacific Underwater Medicine Society Journal 29 (3). ISSN 0813-1988. OCLC 16986801. Retrieved 2008-07-13.

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