Mark V - Real or Repro?

by  Bill Momsen

Edited by Leon Lyons

(Mr. Lyons, a pre-eminent authority on diving helmets of the world, has published a pictorial history of "hard hats" around the world. His book, Helmets of the Deep, may be ordered directly from the author, Leon Lyons, PO Box 190, St. Augustine FL 32085-0190. 370 pages, 860 color photos, 10 1/2" x 11 1/2", over 250 helmets pictured. Text in English, French and German. $287.00, Leather-bound deluxe edition, $487.00. Not many books left.)

Mark V Mark V

Which is the repro? (61K each) (see answer at end of article.) Photo on left courtesy of Seahawk Nautical, photo at right by West Sea Co.

Introduction


How can a genuine Mark V diver's helmet be distinguished from a reproduction? With the genuine example selling for $3800, or even as high as $5600, this is of real concern. As with any other collectible, close examination of as many genuine examples as possible is the best course to pursue. Visiting museums and extensive reading are helpful.

Many manufacturers produced diving helmets. Among the best-known are Augustus Siebe (later Siebe-Gorman), A. J. Morse & Son, Schrader (later A. Schrader's Son), Desco, Kirby-Morgan Yokahama in Japan, and Heinke of England. The best-known helmet is the U.S. Navy Mark V, designed by George Stillson in 1915.

Peculiar to the Mark V is a hinged, rather than screw-in faceplate. The exhaust valve was relocated to the lower right and the head-button modified so that it could be either pulled in using the lips, or pushed out with the chin. Not surprisingly, it was renamed "chin-button". This feature allowed the diver to either increase or decrease exhaust airflow and buoyancy. To guide exhaust air to the rear of the helmet so bubbles would not obscure the diver's vision, a channel was added with perforations at the far end. From its shape, it was renamed the "banana exhaust".

Prior to the advent of the Mark V, all helmets had been provided with breastplate studs from which to hang weights necessary to overcome the buoyancy of the suit. The Mark V was designed exclusively for use with a waist weight belt, the studs replaced by rings used to lash the air hose and telephone cable to the breastplate. In other helmets, side-mounted hooks served this purpose.

The Mark V is no longer being used by the U.S. Navy, having been pushed aside in 1980 by modern plastics. However, the Mark V is still in use in various parts of the world today.

Many reproduction helmets are fairly easy to spot - the various fittings are rather crudely duplicated, and the air and phone goosenecks, the spitcock and exhaust valves do not have passages open to the inside of the helmet. One feature frequently not modeled on repro "hats" are the air passages which guide incoming air to the view ports. On newer repros some of these are indeed modeled, and are extremely hard to detect by the novice collector.

The Bonnet

The helmet was probably subjected to a few hard knocks, unless it was used as a display item since its manufacture. A few dents are to be expected, but have second thoughts about one that has very large dents or is peppered with small ones, as its value as a collector item is lower. Likewise, be wary of a perfect helmet. On helmets intended for U.S. Navy use, look for the inspector's mark - the initials U S with a small anchor between. This will not appear on helmets manufactured for civilian use. Look inside the bonnet for the air ducts, and note if the entire interior is "leaded" (tin plated). Also check if exterior fittings do have openings leading to the interior.

Unique to the Mark V is the hinged face plate. The glass (NOT plastic!) is .030" thick, and beveled. A reproduction spitcock frequently has a loose or "sloppy" action. Of course, it should open to the inside of the bonnet. The spitcock, incidentally, was first installed to take water samples, but was found to be of use by divers, and so retained. The two small holes above the spitcock are used to attach a piece of "sacrificial zinc", an anti-electrolysis agent used to retard corrosion.

A genuine Mark V bonnet is attached to the breastplate with a twist, using the "interrupted thread" arrangement. Again, most repros do not duplicate this feature, although some early repros had a twist-on feature. To lock the helmet in place, a safety lock, or "dumb-bell lock" is used. It should be complete with brass chain and cotter pin. The air and phone goosenecks should be open to the inside. Some helmets had a third gooseneck, for supplying electricity to heated suits. Most banana exhausts have the initials of the manufacturer, BTE (Batteryless Telegraph Equipment Co.), although DESCO manufactured some with a plain surface. On helmets manufactured prior to approximately 1921, an eight point handle was used. Look for the "chin button," a circular brass piece on a stem. This was used by the diver to quickly dump air or obtain more buoyancy without the necessity of adjusting a valve.

The Breastplate

Check the nameplate carefully. Nameplates on helmets manufactured by Morse are elliptical, those by Desco (and those by Morse after 1942) show the month, day and year, and the Miller Dunn nameplates are made of lead. A frequently duplicated nameplate is that of Schrader's - verify that the characters are clean and distinct. Look inside the breastplate for evidence of tampering. The surface directly behind the nameplate should show uniform tin plating.

Although many manufacturers riveted identification plates to the breastplate, Schrader did not. After World War II silver solder was used to attach the various fittings to the bonnet. Scratching the solder joint with a scribe will reveal the type of solder used; lead/tin is softer than silver. Soldering by manufacturers was generally "clean"; look for "messy" bonding or excessive flow around the fitting. Testing solder irregularity is not a conclusive test of tampering, but suggests closer scrutiny.

The first stud on the right side is longer than the others - the "bastard stud," used to attach the air control valve. Two eyelets are mounted on the front of the breastplate, to which the breastplate lanyard lashings attach.

The diver's dress, or suit, has a number of grommets in the collar. To attach the suit to the breastplate these grommets are slipped over the studs. Curved brass pieces, called "brales" are then slipped over the studs and pulled down with wing nuts, sandwiching the suit between the brales and the breastplate. Genuine brales are solid, reproductions may have a channel on the underside. There are no neck ring numbers or vertical alignment marks on the genuine helmet.

English 6-bolt helmets have a channel formed under each brale, into which a raised part on the rubber suit fits.

Serial Numbers

Serial numbers are marked on Mark V and DESCO commercial nameplates. There may or may not be a serial number stamped inside the neck ring of the breastplate. The bonnet should have a number stamped outside the neck ring on the smooth part of the interrupted thread area. Keep in mind that the Mark V was a working helmet, and often bonnets and breastplates were interchanged, so the likelihood of having the same serial number bonnet and breast plate is rather small. Some brales had part numbers on them, some are marked "L" and "R" for left and right, some even had serial numbers. However, large variations in markings have been noted.

Answer to "Real or repro": The repro is on the left; the genuine helmet on the right. Repro photo courtesy of Seahawk Nautical, genuine photo by West Sea Co..

REFERENCES

Leaney, Leslie, A Classic Navy Mark V Helmet, how the Mark V was designed.

Lyons, Leon Jr., Helmets of the Deep, available from the author (see first paragraph of this article).

McKee, Alexander, King Henry VIII's Mary Rose, Stein & Day, New York, 1973.

"Nautical Brass" magazine, Jan/Feb 1981, Sept/Oct 1982, Nov/Dec 1983, July/Aug 1984. Ordering information.

One of the best references is The U. S. Navy Diving Manual, available from the Superintendent of Documents, U. S. Government Printing Office, Washington, DC, 20402, or through your local library.

APPENDIX A: A Brief History of Diving

An age-old question that has plagued man for centuries is: "What's down there?" Free diving (that is, diving without equipment) has no doubt been practiced ever since a caveman made the first underwater plunge after a tantalizing fish. Free diving, however, is limited to shallow depths and for the short time the diver is able to hold his breath, although extended dives have been made by pearl divers using only goggles. Free dives have even been made to the incredible depth of 282 feet, according to the Guiness Book of World Records. A number of would-be record holders have lost their lives in this endeavor.

The earliest written mention of divers appeared in the Iliad, written by Greek poet Homer in the 8th century BC. 500 years later, Aristotle described several devices which supplied surface air to divers, but it is doubtful that any such equipment was actually built.

In the 16th century, almost 2000 years later, a renewed interest in the subject resulted in the description of many diving devices usually consisting of some sort of enclosure with a tube leading to the surface. These ideas represented not much more than wishful thinking, since submerged just a few feet below the surface, water pressure on the diver's chest would make breathing out of the question.

The first diving bell was demonstrated in 1538 by two Greeks in the presence of Emperor Charles V at Toledo, Spain. The divers sat on a platform inside a large inverted kettle which was lowered below the surface. They survived by breathing air trapped in it and emerged safe and dry (as the bell descended, water pressure compressed the air until the two were in equilibrium). The time spent in the device was limited by the amount of trapped air, but it did demonstrate the possibility of men being lowered below the surface.

In 1680 Sir Edmund Halley (discoverer of the comet which bears his name) invented a diving bell made of wood, open at the bottom, and weighted to keep it upright. Weighted casks of air were lowered to Halley and four others who pulled the casks into the bell to replenish their air supply. They remained submerged for an hour and a half at fifty feet.

35 years later, in 1715, John Lethbridge devised a watertight leather case enclosing the diver. It contained "half a hogshead" of air, which in those days was a variable quantity ranging between 32 and 70 gallons. It did allow the diver to roam about on his own without having to scurry back to the bell for another breath of air.

In spite of all those attempts to allow man to explore the fascinating underwater world which awaited him, it was John Smeaton's invention of the air pump in 1788 which made diving practical. The possibility of forcing air under pressure to whatever contraption sheltered the diver below the surface became a reality.

Of the many suits built in that period, one designed by K. H. Klingert in 1797 was perhaps the most successful. It was constructed of leather and tin, covering only the upper part of the body. Used air was simply exhausted from the lower hem of the suit.

In 1818 a farmer's barn in Whitstable, Kent, caught fire. The owner attempted to extinguish the blaze using a small hand-operated water pump, but the stream proved inadequate to quell the fire. He was unable to make his way through the heavy smoke to save his horses. John Deane, then 18 years of age, removed the helmet from an old suit of armor and placed it on the farmer's head. He then operated the pump to furnish air to the helmet, and the farmer was able to enter the barn and lead his horses to safety.

John and his elder brother, Charles Anthony, perfected the apparatus and in 1823 obtained a patent covering a device to protect firefighters, supplying them with air in smoke-filled situations. The two brothers and their father (a shipbuilder) adapted the apparatus for use under water. On his first attempt John, wearing the contraption, simply entered the water. When the water level rose above his helmet, he promptly turned upside down! Their next invention, presumably, was weighted shoes.

Five years later, a practical outfit was developed, helmet open at the bottom, fitted with breast and back plates. Weights were tied to the plates with quick-release knots. Also worn by those early underwater explorers was a suit, or "dress", which was not connected to the helmet. The diver was forced to work in a close to vertical position or water would enter the opening between helmet and suit. Inclining the head would cause the helmet to flood. The Deane brothers became salvage divers, working many wrecks.

An important modification was made around 1830. This was the "closed suit" in which the helmet was sealed to the suit. The diver, being completely enclosed, could work in any position. Although general credit for this innovation is given to Augustus Siebe, according to one source the Deanes had invented it first, and Charles Deane had sold the patent rights to Siebe. Siebe, however, is given credit for the "interrupted thread" on helmet and breastplate, whereby the helmet can be locked in place by giving it a "half twist" (actually one-eighth of a turn). The closed suit design has remained basically unchanged for over 100 years.

The diver first dons heavy woolen underwear (to prevent chafing from the stiff canvas), followed by the waterproof suit. Over this is placed the breastplate, a curved metal plate that covers the upper chest and back, the opening for the neck and head surrounded by a waterproof gasket. The upper edges of the suit are drawn up and over the breastplate, holes in the suit matched to studs protruding from the breastplate. Metal straps, "brales", are placed over the studs and made tight with wingnuts, sandwiching suit between breastplate and brales, resulting in a waterproof joint. The helmet is then dropped into the opening on the breastplate and given one-eighth turn to lock it in place.

By the late 1800s many improvements were made. A valve in the air supply line (lashed to the breastplate) was added, allowing the diver to control his air flow rather than relying on line pulls to signal his tenders. A control knob was added on the exterior of the exhaust valve, allowing him to control his exhaust as well. With the invention of the telephone, two-way voice communication with the surface was possible.

By 1900 even more features were added. The neck gasket was recessed into the breastplate to prevent it from deforming under pressure which could result in leakage, although a French helmet dating to 1855 had this feature. The stem of the exhaust valve was extended into the helmet (the "head-button") to allow a diver to dump air rapidly if necessary.

A few European countries used the 3-bolt neck ring/helmet. The suit neck rubber came out of the breastplate and over the three bolts, and in addition, a 3-bolt gasket set on the non-recessed neck ring. The bonnet was dropped over the breastplate and the three nuts were screwed down, a very simple and extra-safe arrangement. The difficult part was having three men stretch the rubber neck ring of the suit so the diver could swueeze himself past it and into the suit. Presumably, most divers lay on their sides during this operation.

APPENDIX B: Diving Physiology

A brief discussion of diving physics and physiology is useful in understanding how the various helmet features are used. The human body is well adapted to its normal environment, but early divers encountered a variety of never before experienced problems while exploring the deeps. Early designs for diving apparatus consisted of some sort of helmet with a tube running to the surface. This could not possibly work, because just a few feet underwater, pressure on the diver's chest made it impossible to breathe. We live at the bottom of a sea of air, and air does have weight, exerting a pressure of approximately 14.7 pounds on every square inch of our bodies. This pressure is, of course, balanced by the same pressure inside our bodies.

Squeeze

Water, being denser than air, exerts far greater pressure. Descending just 33 feet adds pressure equivalent to the weight of the entire atmosphere at the surface. To counteract the water pressure, compressed air is supplied to the diver. The pressure in all of his body cavities must be equal to the pressure of the air he is breathing or a "squeeze" results. Everyone is familiar with the discomfort felt when descending a long hill in an automobile, or in an airplane landing, when an unpleasant sensation is felt in the ears. The inner ear and sinus cavities have passages leading to the mouth. If these become blocked (during a head cold, for example) pressure in them cannot equalize to the increasing external pressure. This can have serious consequences to a diver - ruptured ear drums or sinus cavities filled with blood. The inner ear is responsible for our sense of balance, and if ruptured, cold water entering the ear can cause a scuba diver to lose his sense of direction. On descent, therefore, it is important that the pressure be increased slowly enough for the body to adjust.

In the early days of diving, no valves were used on the helmet, and some horrible accidents occurred. If the diver's air hose were to break at or near the surface, or the pump failed, pressure inside the suit would quickly drop to atmospheric pressure, and the diver would be crushed as his suit collapsed, squeezing his body into the helmet, and even up the air hose, a "massive body squeeze." One of the first modifications to the helmet was the inclusion of a non-return valve in the air inlet, which automatically closed if the air supply failed.

Embolism

The opposite effect occurs if the diver comes up too quickly, without allowing his body pressure to equalize. The reverse of a squeeze, this is known as "air embolism," which, in severe cases, may actually burst the lungs. The remedy is simple; do not hold your breath while ascending. Air embolism can occur in water as shallow as 4 feet. In fact, it causes a real problem when working in shallow water with surge. As a wave passes by overhead, the diver may be subjected to rapidly changing pressures.

The weight belt and weighted shoes give the diver negative buoyancy; this is counteracted by the amount of air he keeps in his suit. The air control valve lashed to the breastplate controls the flow of air into the suit, and the amount of air leaving is adjusted by the exhaust valve. The diver can "fine tune" the amount of air leaving by cracking the spitcock. One of the worst disasters to befall a diver is "blow-up," caused by loss of weights or improper suit inflation. In this situation, the diver acquires positive buoyancy, and starts floating upwards. As the water pressure decreases, the air in the suit expands, causing him to rise more rapidly. The end result is the diver floating helplessly on the surface, arms and legs rigidly extended, perhaps with a dangerous air embolism.

Decompression Sickness

The design of the Brooklyn Bridge called for stone masonry towers on either side of New York's East River. This required sinking caissons to a depth of 75 feet below water level. To keep water out of the caissons, they were sealed, and compressed air forced into the chamber. As excavations went deeper, air pressure was increased to balance the water pressure. A strange malady, known as "caisson disease" soon afflicted many of the workers, a syptom of which was excruciating pain in the joints. In 1876 French physiologist Paul Bert discovered the cause, too rapid release of nitrogen dissolved in the blood.

A similar problem plagued early divers as they went deeper. Frequently, shortly after they were brought to the surface, they experienced pain in the joints, and assumed a bent-over position. This "disease" was "the bends", now renamed "decompression sickness". The cause again is too rapid ascent, but for a different reason. Air consists primarily of two gases - oxygen and nitrogen. As the diver descends, increased pressure causes more of these two gases to be dissolved in the blood. Upon ascent, the gases must leave the bloodstream. Oxygen, being lighter, is released more quickly than the heavier nitrogen. If the diver ascends too rapidly, small bubbles of nitrogen form in the blood, causing clots, which often lodge in the joints. The longer and deeper the dive, the more nitrogen is absorbed by the body. A diver can remain in the water indefinitely if he goes no deeper than 33 feet. On deeper dives, he must limit his time on the bottom according to the depth worked. Tables have been worked out giving safe times at various depths. For example, he could remain one hour at 60 feet, but only 5 minutes at 150 feet. If he exceeds the safe limits, he must pause on the way up to "decompress." Decompression tables give the depth and time required. For example, a diver working at 190 feet for 25 minutes must stop for 5 minutes at 30 feet, 11 minutes at 20 feet, and 25 minutes at 10 feet. Once on the surface following a dive, it takes time for the excess nitrogen to leave the body tissues. If the diver makes a second dive within 12 hours, the effect of the residual nitrogen must be taken into account. Repetitive dive timetables have been developed which the diver must follow to dive safely.

Nitrogen Narcosis

Nitrogen causes another problem - at depths below 50 feet it has a narcotic effect, causing "nitrogen narcosis," or "rapture of the deep." Susceptibility to nitrogen narcosis depends upon the individual; some are more prone than others. The euphoric condition which results is similar to that produced by the consumption of alcohol. There is a rule of thumb, "Martini's Law," which states that with each 50 feet of depth, the effect of nitrogen is the same as that produced by drinking one Martini on an empty stomach. At 100 feet it is equivalent to two Martinis, at 150 feet three, and so on.

To counteract this, helium is substituted for nitrogen in the "mixed gas" diving apparatus. Some helium-oxygen helmets are modified Mark Vs, a canister filled with a carbon-dioxide absorbent attached. They can be recognized by a number of extra fittings attached to a standard Mark V. Air is composed of approximately 80% nitrogen and 20% oxygen, plus small amounts of other gases. Since the human body only needs oxygen, why lug around all that extra nitrogen? Dives can be made using pure oxygen at shallow depths, but it becomes toxic at depths over 33 feet.

Other Hazards

Although helium-oxygen mixtures eliminated nitrogen narcosis, another problem soon appeared. As divers pushed their way down past 1000 feet, hyperactivity of the brain occurred. It was found that the problem was solved by adding 10% nitrogen, named "trimix."

Most problems occur upon ascending or descending, and on deep dives bottom time is severely limited. In "saturation diving" the divers stay down for days or weeks at a time, in a protective chamber similar to the diving bell, which was first demonstrated in 1538! In such divers the pressure of the gases in the body come to equilibrium with the compressed gases they breathe. Of course, they must decompress slowly before returning to the surface. In addition to the hazards outlined above, the diver is also subject to hypoxia (not enough oxygen,) excessive carbon dioxide, carbon monoxide poisoning (from air compressor exhaust fumes entering the air supply,) fouling (getting the lines tangled up,) physical injury, overexertion, exhaustion, not to mention attacks by unfriendly sea creatures. Are you still sure you want to go diving?


Suggestions welcomed! Mail us at:

To see why we made it difficult to to contact us click on the explanation.


Return to Nautical Brass menu


Last update: 11/12/00
Copyright © 1999 - 2001 Nautical Brass. All rights reserved.
since 4/27/99