Dry-Suits

Hailed as a prophetic masterpiece of science-fiction when it was first
published in 1869,  Jules Verne's, "Twenty Thousand Leagues Under the Sea",
overlooked the earlier achievements of Augustus Siebe and his diving helmet
and standard flexible dress.  A diving breakthrough that had, since 1837,
made it possible for divers to work underwater for extended periods of time
in warmth and comfort.  ('Warmth' and 'comfort' - in this context - are
relative terms!)

Borrowing heavily from the inspired work of two fellow countrymen,
Rouquayrol and Denayrouze, (who were working on the prototype of a SCUBA
system), Verne imagined a diving dress of, "heavy and impervious clothes,
made of India rubber without seam, and constructed expressly to resist
considerable pressure. One would have thought it a suit of armour, both
supple and resisting. This suit formed trousers and waistcoat. The trousers
were finished off with thick boots, weighted with heavy leaden soles. The
texture of the waistcoat was held together by bands of copper, which crossed
the chest, protecting it from the great pressure of the water, and leaving
the lungs free to act; the sleeves ended in gloves, which in no way
restrained the movement of the hands. There was a vast difference noticeable
between these consummate apparatus and the old cork breastplates, jackets,
and other contrivances in vogue during the eighteenth century."

But as long as diving remained a work related activity there was little need
to consider any changes to Siebe's simple, proven and practical diving
dress, a one-piece suit made from sheet rubber contained between two layers
of canvas twill and with vulcanised wrist seals.  Rugged enough to resist
abrasion and the hazards of working around wrecks the standard diving dress
offered the user protection from both the cold (by allowing a variety of
undergarments to be worn), and the crushing effect of pressure at depth,
(air circulated freely into the suit from the attached helmet.)  That it was
bulky and unsuited to free swimming was of little consequence and hardly an
issue.

It wasn't until the 'twenties and 'thirties - largely   through the
syndicated writings of ex-patriate American, Guy Gilpatric - that the
exploits of a loose knit group of Mediterranean spearfishermen seized the
public imagination and thought was given to designing more appropriate
protection.  Turning pieces of equipment intended for other purposes to
their own use, these early pioneers of sport diving were spending longer
times in the water, usually clad in nothing more than a swimming costume or,
occasionally, a woolly jumper.

It was then that a few individuals began experimenting with readily
obtainable, latex rubber.  Fashioning suits of this fabric, with seams glued
and taped together, the designs were largely unsatisfactory affairs that
provided nothing in the way of thermal protection.  Warm clothing was a
pre-requisite and there was still the problem of compression with depth.
Vital anatomical parts trapped between a crimp in the suit would bring tears
to the eyes and cause many a diving pioneer to abort their dive!

Often in two pieces, top and bottom, the diver would struggle into both
halves of the suit, taking care not to damage or tear the delicate material.
The two halves were then rolled together at the waist and sealed by
wrapping - and sometimes gluing! - another piece of latex around the join.

Other designs featured a large mid-section opening with plenty of spare
material which, after the diver had entered the suit, was gathered together,
folded and fastened using a knot or, later, specifically designed clamps or
rings.

In some cases an integrated hood that sealed around the eyes, nose and mouth
was incorporated into the suit, only the wrist areas requiring necessary
cuffs and rings to prevent water entry.

Even Cousteau, prior to developing the Aqualung regulator, experimented with
dry suit design discovering, in the process, some of the inherent problems,
including that of maintaining neutral buoyancy and preventing air rushing to
the feet of the suit when attempting to swim down.

Easily susceptible to cuts and tears it was often found desirable to wear an
outer overall in order to maintain the latex dry-suit's water-tight
integrity - and there still remained the problem of maintaining the suit at
a constant volume while the diver was at depth.

Both of these obstacles were partly overcome during the Second World War.
Diverting substantial resources into military research, governments quickly
began to appreciate the many and varied tasks that divers could be called
upon to perform.

The outcome was an assortment of dry-suits made from a variety of
materials - ranging from the heavy-duty, standard flexible dress to
lightweight, streamlined designs - many intended for specific applications.

The most enduring of these dry-suit designs was that worn by the 'frogmen' -
free-swimming, attack divers.  Constructed of rubber spread upon stockinet
and fitted with latex wrist cuffs and plimsoll rubber boots the suit was
entered through a 10-centimetre hole in the highly stretchable, rubber neck
yoke and sealed by either a latex neck seal or full hood that clamped to the
yoke.  Fitted with an optional inflation valve connected to a small air
cylinder held in place by a harness, these suits overcame the problem of
compression at depth.

After the War, dry-suits remained relatively expensive items whose use was
largely confined to the military or commercial sectors, or to the growing
band of professional undersea researchers like Cousteau.

Still seeking proper thermal protection when cold water diving, Cousteau, in
1946, introduced his Constant Volume Dress, a one-piece rubber suit with
exhaust valves at the head, wrist and ankles to keep the diver stable in any
depth or position and inflated by the diver's, "nasal exhalations, blown out
under the edges of an inner mask."

But in the early 'fifties, as recreational diving began to gain in
popularity, equipment manufacturers responded to the growing demand for
warmth and comfort.  Equipment catalogues from 1955 feature a number of dry
suit designs, several of which were based on the home made models of the
pre-war years and with prices that started from (by today's standard!) as
little as US$45.00.

The U.S. Divers Corporation marketed several types of dry-suit, including
the, "Seal Suit - This cold-water suit is the final development of countless
experiments in the cold pacific; made of pure gum rubber, it keeps the diver
warm and dry indefinitely, while retaining 100 percent manoeuvrability."
With a choice of long or short arms and legs the top of the range suit cost
just US$54.95!

Even the, "Pirelli Suit - A two piece suit that enables the diver to get in
and out without help; used by the United States Navy and made by the most
famous European rubber manufacturer" had a top price of just US$70.00.

(Paradoxically, in that same year a foam neoprene wet-suit from
manufacturer, Fenjohn, cost US$75.00!)

By comparison the, "Captain Cousteau Constant Volume Suit - (Pat. No.
2,593,988), a suit that was favoured and used by Royal Australian Navy
divers during operations in the early 'sixties, retailed for US$245.00!

Regrettably for the evolution of the dry-suit, the boom in recreational
diving coincided with the widespread introduction of foam neoprene.  A
relatively inexpensive material that lent itself to the DIY aspirations of
many sport divers, neoprene provided sufficient thermal protection to meet
the needs of their usual single, thirty-minute dives.  Easily repaired and
with no need to worry about suit inflation devices or punctures, wet-suits
became the protective covering of choice for a majority of divers, even to
the extent of being worn under dry-suits when extreme protection from the
cold was required!

Thought of as cumbersome, expensive, difficult to maintain and requiring
extensive training in their use, dry-suits fell out of fashion.  But today
they're back with a vengeance.

Thanks to a new generation of robust and lightweight fabrics, many of today'
s dry-suits offer the same protection that Augustus Siebe sought for users
of his equipment, but with non of the associated bulk and weight.

Although dry-suits are now constructed of virtually any material capable of
forming a watertight barrier, the most popular have proven to be:-
Tri-laminates:  In which a thin layer of butyl rubber is sandwiched between
two layers of tightly woven fabric.
Neoprene:  Like most of the neoprene family of dry-suits, they are usually
protected by a nylon outer and inner lining to protect the material from
nicks, tears and punctures.
Crushed neoprene: Denser than wet-suit material by virtue of the fact that
the gas cells have been eliminated.
Micro-cell neoprene:  Containing smaller gas bubbles than those present in
ordinary neoprene and offering a higher level of stand-alone thermal
protection than, for example, Crushed Neoprene.
Vulcanised Rubber: Usually with an inner lining, the smooth, heavy duty
rubber is easily washed down and cleaned after diving in contaminated
waters.

Advanced construction techniques and the use of watertight zips have
overcome the difficulties experienced in the past of getting into and out of
a dry-suit.  Fitted with a choice of neck and wrist seal materials and
featuring inlet valves that allow easy suit inflation and exhaust valves to
maintain the internal pressure of the suit at a constant volume, the modern,
one-piece dry-suit provides the wearer with previously unimagined warmth,
comfort and ease of use.

With a life expectancy two to three times greater than that of a wet-suit, a
dry-suit is more than just an economically sound investment.  With the
growing trend towards multiple dives for deeper and longer, a dry suit
should now be regarded as an essential equipment item.


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