Deep Sea Diving


Article written for Military Vehicle Magazine by Vince Scarponi

Militray diving equipment

Navy Mk V equipment


Below is an article written by Richard Boyd and published in the Fall 2005 issue of Mari-Times, the newsletter of the Door County Maritime Museum. It is presented here courtesy of DCMM. Thanks to Assistant Curator June Larson for providing the photos from the article.


Door County Maritime Museum & Lighthouse Preservation Society

Wisconsin Underwater Archeology Association

Door County Maritime Museum & Lighthouse Preservation Society  Mari-Times  Fall 2005

Volume 13, Issue 4 Fall 2005

Jackson Harbor 1908

A Commercial Diver's Story: The Career of Pearl Purdy

by Dr. Richard Boyd

Wisconsin Underwater Archeology Association

Richard J. Boyd, Ph.D. in microbiology and oceanography, has been an active diver since 1954, specializing in shipwreck, TEK, and commercial diving, including underwater demolition. PADI national diving instructor for 35 years. Director of Wisconsin Underwater Archeology Association and instructor for underwater archeology courses. Presenter of national workshops on mixed gas technology, pressurized oxygen management, and scuba equipment maintenance. Currently Technical Director of Global Mfg. Corp., a major producer of SCUBA test apparatus and gas mixing equipment in Milwaukee.

The commercial diving and salvage industry on the Great Lakes has been an important, but generally unsung sector of maritime history. In the late 19th  and early 20th centuries, nautical accidents and waterfront mishaps were daily occurrences at one place or another around the lakes. This resulted in a steady demand for underwater repair and recovery services which were performed by early commercial divers. Nicknamed "hard-hat divers," these men (and a few women) used a copper metal helmet mated to a counterweighted canvas suit to descend to their workplace. Compressed breathing air was delivered by crude rotary hand pumps which operated progressively harder as the diver went deeper, and usually kept several "pumpers" hopping to maintain the required gas supply.

These subaquatic workmen operated in a dangerous environment using primitive equipment with only fledgling knowledge of diving physics and medicine. As a result, some of these individuals met with an untimely watery demise or suffered crippling injuries which haunted them in later life. In that era, very little was known about the bone and tissue-crushing damage that could be inflicted by water pressure. Even less understood were the disabling effects of decompression sickness, commonly called the "bends," which struck divers who went too deep or stayed too long at depth. The toxic, incapacitating embrace of nitrogen narcosis during deep dives was largely a complete mystery, and was simply referred to as "Divers' Blackout."

Besides the danger factor, early divers worked for wages which today would seem pretty paltry, although they were considered good money in those days. For example, in 1901 at Detroit, a new Divers' Association was formed which established rates for work under the Great Lakes. Divers received $10.00 per day; tenders got $3.00; pumpers got $5.00, and general helpers, about $3.00.

As maritime casualties increased after the Civil War, professional wrecking and recovery businesses sprang up across the lakes, staffed by personnel specializing in vessel reclamation and rehabilitation. There was never a huge contingent of trained divers on the lakes at any given time, but nearly every major port was home base to a wrecking company and some underwater workmen. Surprisingly, even small ports such as Marquette, Cheboygan, St. Ignace, Grand Haven, and Manistee boasted a local resident diver. The "Divers' Advertising Section" of Beeson's Marine Directory for 1914 listed about 25 companies and individuals offering underwater services on the western lakes. The deeds of some of these men such as Tom Reid of Sarnia and the Falcons of Chicago became legendary.

Pearl E. Purdy diver

The life and times of an early 20th century diver were exemplified by the career of Wisconsin's own Percy E. Purdy. Known far and wide by his nickname "Pearl," Purdy worked for various Great Lakes wrecking and salvage companies, while also operating his own commercial diving service. He sought (and found) steady work around the lakes as detailed in his yearly advertisement found in Beeson's Marine Directory (see reproduction above). A 20 ­year resident of Sturgeon Bay (WI), he was originally from the Detroit area where his three brothers and two sisters still resided. In 1907, he married May Donovan of Sturgeon Bay; they had two children.

Most of Purdy's jobs were typical of the sort of underwater engineering and maintenance duties performed by divers of that era. Many of these tasks were routine, if not mundane or unpleasant. They included the inspection and caulking of ship hulls, repair of vessel machinery, retrieval of lost items, harbor maintenance chores, and body recovery. Purdy was always busy during the shipping season as typified by the summer of 1913. In April of that year, Pearl recovered the rudder of the big steamer George F Baker which had been lost in the Manitowoc River. He extended his stay in Manitowoc into May to do some routine harbor maintenance at the shipyards. In early June, he raised the tug Duncan City which had sunk in a local waterway and also contracted to raise another small tug later that summer. This second vessel, the Minnie Warren, had sunk in a nearby shipyard. That period also found Pearl inspecting the hull of the tug John Hunsader at Sturgeon Bay. Come September, he returned to Manitowoc to plug a leak on the steamer Rend. When not busy in Wisconsin waters that season, Purdy's talents were in demand by various salvage and wrecking firms around the region, including that of such famous mariners as Captain John Roen of Sturgeon Bay.

Over the years Purdy inspected and repaired many prominent lake vessels, some of which became Wisconsin shipwrecks. In 1915, he caulked the leaky hull of the steamer City of Glasgow, which eventually was converted into a Wisconsin stone barge. The Glasgow, at 297 feet, was one of the giant wooden ships produced by the famous Davidson Shipyards in Michigan. Today it's a wreck resting in Lilly Bay near the Sturgeon Bay Ship Canal and was recently studied by underwater archeologists from East Carolina University. The wooden steamer Atlanta, which burned and sank in 1906, was also explored by Purdy who determined that its porcelain cargo had been ruined and was not worth salvaging. In modern times, this shipwreck near Port Washington has been a popular dive site.

Like most divers of that day, Purdy had some harrowing misadventures and close-calls. Perhaps his greatest escapade came during the salvage of the John M. Nicol, a wooden freighter which stranded and sank off Big Summer Island (MI) in December 1906. Its cargo included 2,500 tons of valuable coiled barbed wire which immediately became the target of salvors. The portion of the Nicol remaining above water was rapidly stripped by thieves from the Garden Peninsula. Among these robbers was the infamous Captain Dan Seavey, the only mariner on Lake Michigan ever to be arrested for piracy!

In late February 1907, as ice conditions on the lake abated, professional salvager Captain Coffey cruised to the wreck site to recover the barbed- wire. His men installed a ladder from the surface of the ice into the hold of the Nicol and Diver Purdy descended into the vessel. While wrestling with the coils of wire, Pearl accidentally fell underneath the engine and boiler. The fall apparently injured and disoriented him and, while trying to find his way back to the ladder, he actually staggered around it twice. This maneuver thoroughly entangled his lifeline and air hose and soon choked off the gas supply.

Purdy's tender, Frank Isabel, quickly realized that no signals were coming up the lifeline. Alarmed at this lack of response, the surface crew pulled Pearl feet-first to the surface, ladder and all. Isabel, at great personal risk, leaped into the icy water and cut the fouled lines so that Purdy could be hauled aboard the salvage tug. He was unconscious and bleeding profusely from his mouth, ears, and nose. Isabel was suffering from hypothermia. Both men were rushed by boat to Manistique (MI) for medical treatment. After a few days, they had recovered sufficiently to return to work. Two weeks later, Purdy and Captain Thomas Isabel, assisted by brother Frank, resumed the salvage work and recovered all the wire from the Nicol! This is quite amazing by modem standards ... today medical experts would probably disqualify a person from future diving after suffering a serious case of barotrauma (pressure damage) such as Purdy had obviously endured.

In many situations, divers of that era had to be a jack-of­-all-trades, and Pearl was no exception. They routinely had to perform a variety of mechanical repairs, often involving underwater metal cutting, rigging, lifting, or dredging. Occasionally, they even had to employ specialized paraphernalia such as explosives. As previously suggested, the "fine points" of using such technical material often was not appreciated. In 1908, Purdy was working on the sunken tug Kate Williams in Jackson Harbor on Washington Island (WI) (see photo, page 1). Dynamite was being utilized to shear the shaft and propeller from the derelict. As reported in the Door County Advocate, Purdy lost the thumb and index finger of his left hand due to the premature detonation of a blasting cap. As is often the case with old newspaper accounts, sometimes only part of the story is presented, and so it was with this Purdy incident. Raymond MacDonald, Washington Island historian, recorded the "rest of the story" in 1985.

It is well known to underwater blasters that the concussion from an explosion instantly kills any nearby fish, which promptly float to the surface. Moreover, the force of the blast literally filets the fish, allowing all the bones to be quickly and easily removed. Although an illegal act, explosives have occasionally been employed to facilitate a quick fish-fry! It seems that Purdy, preparing a blasting cap for this very purpose, was carelessly picking at it with a pocket knife when it suddenly went off!

Having lost two digits on his hand, Pearl was taken to the MacDonald's residence; they, in turn, rushed him to the doctor's office, about seven miles away. It was very apparent that his finger stubs would have to be trimmed and stitched up, a most painful operation. Thus the crew stopped en route at Charlie Johnson's where some whiskey was procured to use as a surrogate anesthetic. By the time they arrived at the clinic, Purdy was "feeling no pain" and ready for surgery!

During the late fall and winter seasons when diving jobs were few, Pearl often worked on lake freighters as a cranesman. He had done this successively for about 16 years, and it was this part-time occupation that eventually cost him his life. In September 1924, he shipped out aboard the whaleback freighter Clifton which was transporting a load of, limestone from Sturgeon Bay to Detroit. At this same time, Purdy's wife and two children were moving to Detroit where the family was planning to establish a new home.

As the Clifton headed into Lake Huron, a nasty storm rolled in from the southwest. Sometime on September 21, the vessel disappeared with its entire crew. The freighter was last seen by the tug Favorite slogging along near 40­-Mile Point, and it is assumed that she foundered about 25 miles off Thunder Bay. Some bodies were recovered on the Canadian shore of Lake Huron, but Purdy was never found. The Clifton itself still remains one of the true ghost ships of the Great Lakes. Thus the lakes inducted 42-year old diver Pearl Purdy as a permanent resident of that watery kingdom where he had made his living for so many years.

Diving Historian/writer Kent Rockwell

A few weeks ago HDS member, diving historian/writer, and our friend Kent "Rocky" Rockwell passed away after a long battle with cancer. Rocky had written articles for HDS USA Historical Diver/Journal of Diving History and HDS SEAP Classic Diver. Below is an article we collaborated on with him as it appeared in issue 59 Spring 2011 of Classic Diver Magazine. Our thanks to Jeff Maynard and HDS SEAP for allowing us to reprint here.

Historical Diving Society South-East Asia - Pacific


DESCO’s US Navy MK V, Mod 1, Diving Helmet

By Kent Rockwell & Ric Koellner

The United States officially entered World War II with the bombing of Pearl Harbor on December 7, 1941. With the increase in war materials production, the US Navy quickly updated their blue prints for the MK V, Mod 1, standard deep-sea diving outfits by April 6 of 1942. They then sent these drawings out for tender.

Known MK V diving equipment manufacturers Schrader and Morse were obvious choices for contracts (the MK V was developed in 1915 and first produced in 1916) but the little known Diving Equipment and Salvage Company (DESCO) had also received the drawings and by the end of the War they had produced more than 3000 MK V helmets…making DESCO the largest diving equipment manufacturer in the world.

DESCO’s owner, Ric Koellner still manufactures the MK V, Mod 1, outfit in all its classic beauty. In every detail these works of art are made from the original WW II drawings and tooling. In order to understand how difficult these hand-crafted icons are created Ric has offered a “behind the scenes” tour of their building process and in doing so one soon realizes the magnitude of the project undertaken not only by Jack Browne and company, during the war.


By December of 1942, some eight months after the blue prints were finished; DESCO had produced upwards of 100 sets of MK V gear (the first helmet Ric has in DESCO’s historical record is #170 dated 12/20/42 and the last is #3088 dated 12/5/45. Ric thinks DESCO started numbering at 100). Thus, in a very short period of time a complete production facility was built to manufacture, not only the helmet and breastplate but the rest of the diving outfit as well. Fortunately for DESCO’s co-creators, the innovative Max Gene Nohl and his companion Jack Brown, Norman L. Kuehn stepped in as partner and vice president in the fledgling enterprise. Kuehn was already a successful rubber goods manufacturer and, initially, in 1938, housed DESCO in his Kuehn Rubber Co. building at 1053 N 4th Street in Milwaukee, Wisconsin. By 1940, Nohl had sought the more lucrative lecture circuit to tell the story of his historic 420 foot record helium/oxygen dive back on December 1, 1937, leaving Browne and Kuehn with the struggling company. By 1942 DESCO was in its’ own facility at 922 N 4th Street, also in Milwaukee (the city known as the “nations machine shop” before the war). Kuehn provided the capital, the managerial expertise and the contacts to develop the new company. The first step in building the MK V helmet required drawings of the individual parts. The USN drawings consisted of ten sheets. The General Arrangement drawing indexed the succeeding nine composite drawings. DESCO produced individual parts drawings from these ten sheets and then developed a production line flow chart. The drawings were sent to the new shops where the necessary machinery, tools and fixtures were organized on the production line process. The parts that were machined from raw stock had the materials shipped directly to the shops. Parts to be sand cast were created in wooden patterns first and then sent to the foundry where the rough castings were poured. These castings were then returned to DESCO for machining. Spinnings of the helmet shell were done in house and the resulting goal was to have all of these parts finished and in stock, ready for final assembly at the soldering stations. The MK V helmets were then tin plated and sent to final assembly. The MK V helium/oxygen helmet was the standard MK V hat modified with a venturi injection system and CO2 scrubber to conserve the rare helium. It used many of the same parts and was built right along with the MK Vs on the same assembly line.


Today, DESCO produces some twenty sets of parts on a typical production run. The helmet assembly is referred to as the top and the bare spinning as the shell (DESCO never called the shell a bonnet). The shell is spun from .064 inch thick copper sheet at a local Milwaukee spinning house. This ages old technology uses a robust spinning lathe with the wooden helmet mandrel (or male mold) attached to the headstock in the horizontal position and a pressure plate held in the tail stock. What appears to be a rowboat’s oarlock replaces the lathe’s cutting tool post and the oars are bars of steel with different shaped rollers on the ends. The copper sheet is initially pinched between the mandrel and the tail stock in the annealed condition. The husky operator forces the roller bar against the spinning sheet using the tool post for leverage. Gradually the sheet is worked down against the mandrel…from the shells top center on down or from the tail stock toward the headstock…as seen from the operator’s point of view. As the copper sheet is spun it becomes “work hardened” and must be removed and annealed with a torch to keep the copper malleable. It is returned to the lathe and the process is repeated several times. At various stages the excess wrinkled sheet is trimmed away from the edges to allow the metal to form more closely. When the sheet is smoothed down onto the mandrel; the whole assembly is removed from the lathe and, since the shell tapers down to a smaller diameter at the bottom, the center wooden blocks are pulled out first…allowing the outer pieces to fall inward and then be extracted. A simple process once you’ve seen it. Back at DESCO the shells are cleaned and media blasted. To finish the shell a “layout pattern”, made from a slightly larger spinning, is used to mark the holes in the shell. With a split down the middle and a hinge at the top, the tool is clamped over the new shell and a pencil scribes the holes to be cut. The shells are then placed in a holder on the drill press and hole saws of appropriate sizes are used to cut the openings.

DESCO part production

The majority of the MK V parts are made from sand castings. The original wooden patterns are bonded to a base plate along with the runners between multiple parts and the risers. The risers are the vertical shafts where molten metal is poured into the mold and also vented. The patterns are packed with sand in a stout wooden box (flask) and then removed leaving the hollow, part shaped, cavities to fill with metal. These wooden patterns have stood the test of time but occasionally need minor touch-ups. Automotive body filler works quite well for the nicks and cracks, and a final spray of a silver powdered release agent finishes the outer surfaces. All of the MK V sand cast pieces are poured from 85/5/5/5 Red Brass (or bronze), that is, 85% Copper, 5% Tin, 5% Lead and 5% Zinc.

The interrupted thread neck rings fasten the helmet and the breastplate together with a simple 1/8th turn to engage the threads and tighten in place. The female and male neck rings each have their own casting. The male neck ring casting with its’ protruding threads and recess for the leather gasket is larger than the female ring. The threads are single point cut, on the lathe, to 6 threads per inch and the two parts are then screwed together. An index mark is stamped on each ring to establish the center point. Then the 1/8th segments are milled out with the rings still assembled to assure proper alignment.

The air-regulating exhaust valve is one of the more critical parts of the helmet. The present design was adopted by the US Navy in 1931 and features dual springs of phosphor bronze. Mounted on the right side of the helmet the hollow banana shape channels the exhaust bubbles behind the faceplate and out of the divers view. The valve automatically maintains about one-half p.s.i. pressure in the helmet and dress, in excess of the outside water pressure, and manually allows the diver to adjust his buoyancy with the star shaped hand wheel on the outside of the helmet and the chin button on the inside. The casting’s pattern is fairly intricate with both the curved external shape and a separate sand core for the internal channel. Once cast …the sand is pounded from the internal channel, the risers are cut away, and the outside surfaces are ground smooth and polished. Since the exhaust valve assembly is machined into one end of the banana shape a complicated piece of tooling is mounted to the face plate of the lathe to hold the rough casting. This centers the valve end of the casting for machining while allowing the exhaust end to swing free to whack the careless machinist. The internal and external valve pieces are machined from small sand castings or turned from free machining brass stock and will be installed during the final helmet assembly. War year Mark V helmets used exhaust valve assemblies made by BT&E. Production drawings from February of 1951 suggests that DESCO started making their own parts at that time. The supplementary exhaust valve is mounted on the left front of the shell. Called a spit-cock, this valve was originally installed to allow the diver to pull in a mouthful of water to “spit” onto the lens to defog them and can be used for minor buoyancy adjustments. The body and handle are made up of small castings taper reamed and lapped to pivot smoothly together, alignment drilled for the air/water passage, and polished.

The sand cast bronze telephone and air-inlet gooseneck fittings, located at the rear of the shell require both internal and external sand cores and lathe mounted tools for machining their threaded ends. Both fittings are angled inward and their flanges, with backing washers, are drilled in three places for riveting to the shell before soldering. The telephone gooseneck is mounted on the diver’s left side and has the internal transceiver connection. Its’ cap is machined from a brass casting and uses a leather seal. On the right side, the air-inlet gooseneck fitting is machined for the standard submarine thread of 1 1/16th- 17 threads per inch. Mounted to the inlet fitting is the all important non-return check valve. Its’ body is machined from solid brass hex stock and features a light spring and leather gasket seat on the early valves and a cartridge insert and O-ring on the later models (a change made by the USN in1962). The non-return valve uses the same submarine thread to attach the air line and its’ cap is machined from solid brass with a leather gasket seal.

production DESCO diving helmets

There are four viewing ports soldered to the shell. Originally, safety glass was sealed in place with a Red Lead compound. By the time Ric Koellner started working for DESCO in 1980 they had switched to using the current Litharge (PbO) and Glycerin. After WWII the Navy changed the lens specification to acrylic plastic. The oval top and round side ports are sand cast rings with polished cast brass guards. These rings are ground smooth, machined for the acrylic lens and drilled and tapped for the guard’s 10-32 screws. The front port has a hinged faceplate and a guard of polished cast brass as well. Both the faceplate and the door base are machined to mate with a groove for the rubber sealing gasket and the faceplate is recessed for the lens. At its hinged side…the faceplate and ring are milled for a perfect fit and drilled for the pivot pin. The pivot pin has two holes drilled for cotter pins; the lower hole is used when the welding shield is fitted. The faceplate is held closed with a toggle bolt and a wing nut. The toggle bolt (called swing bolt in the USN Diving Manual and screw bolt on the USN drawings) is machined from free machining (FC for free cutting) Yellow Brass square stock on the Brown & Sharpe Wire Feed Screw Machine. Once the ½-13 thread is cut, the square end is drilled for its’ pivot pin and rounded to clear the inside of the hinged recess. The threaded end is necked down to 5/16th inch for about a thread for a brass retaining washer. The bolt will be pinned in place before tinning the helmet. The polished cast brass wing nut is drilled and tapped for the ½-13 thread. It has a tapered seat to lock into the faceplate’s countersunk recess and once closed the faceplate seals against the flat gasket. The safety lock dumbbell lever and its’ pivot body is machined and pinned together. It will be soldered and tinned on the helmet as an assembly.

On the inside of the helmet resides a .020 thick sheet copper air duct with branches leading from the air-inlet gooseneck to the top and side ports. The four sections are hammered over steel mandrels and will be soldered into the shell when the helmet parts reach the soldering station. These ducts channel the incoming air away from the divers head and helps keep the ports clear of moisture and fogging.

The twenty pound breastplate attaches to the helmet with its’ matching interrupted thread neck ring. The USN drawing calls the breastplate the collar and the collar’s shell is the thin sheet. The shell of the breastplate begins with a square of .046 inch thick copper sheet. The neck opening is scribed in the center, well inside the finished diameter of 7 ¼ inches, using a compass and then cutout using a hammer & chisel.  The sheet is then folded into a U shape over the operator’s knee to conform to the female mandrel and is then clamped in place. The sheet is continually heated and annealed with a rose bud torch while being hammered down into the 1 ½ inc thick steel mandrel with water soaked maple mallets. The metal is heated and annealed while being stretched with the mallet to prevent it from tearing. A heavy 1½ inch wide cast brass collar ring (or bottom strap) will be soldered around the edge the edge of the shell stiffening the breastplate’s flange. The ring is ground smooth and shaped to the contour of the breastplate.

Production DESCO Diving shoes

the shell is placed over a heavy steel male mandrel, the collar ring is clamped down over it. The edge of the copper sheet is trimmed and then peened over the ring, ready for soldering. Four, heavy, straps, called brails (short for brass rails), are drilled, ground smooth and polished to fit the studded flange and are stamped “front” and sometimes “back”. These brails (also spelled brales) are called “sectional collar straps” on the USN drawings. They will clamp the dresses’ rubber neck gasket to the breastplate providing a water tight seal. Eyelets are ground and polished from small castings and will be soldered to the front of the breastplate. These are used to tie off the air hose and communications/life lines to the front of the breastplate. The twelve studs are cut on the B&S Screw Machine…threaded ½-12 from 5/8 inch round bar stock leaving a 3/16 inch head.  As noted the “bastard” stud, is slightly longer. And, finally, the twelve wing nuts are drilled and tapped to ½ inch -12 thread to fit the studs and polished. There are eight regular nuts and four with large flanges to fit over the gaps at the ends of the brails.


DESCO’s MK V flow chart funnels all of the manufactured parts together at the soldering station. The first concern is that the parts are thoroughly cleaned and ready for assembly. Soldering parts to the shell begins with the heavier items as they require more heat and would dislodge smaller parts. Liquid soldering flux is brushed on the surfaces to be soldered and a bar of 50/50 solder is used. That is a mixture of 50% lead and 50% tin. As long as the parts are clean the soldering goes smoothly. The main problem Ric has found when repairing older helmets is that oxidation and contamination will prevent the solder from flowing hence the need to media blast the area and, unfortunately, a lot of solder, tinning and/or the much desired “patina” must be removed when trying to repair even a minor defect.

The female neck ring with its indexing mark to the front is soldered onto the shell first, using a standard oxy-acetylene torch set. The operator must bring the heavier parts up to temp without overheating the thin shell. Next is soldered the four port rings starting with the front, top and then side ports, then the welding lens bracket and the banana exhaust, all requiring a fair amount of heat. The banana exhaust is riveted to the shell at the aft end with a copper rivet and clamped at the forward end with a threaded washer inside the shell before soldering.

The safety lock’s dumbbell (ball lever) pivot pin is retained by peening over its’ retaining washer and then the small assembly and the spit-cock’s body is clamped thru the shell with a threaded washers on the inside and then soldered in place. The transceiver’s cup is soldered in place over its’ cutout. On the back of the shell the two goose necks are riveted on with three copper rivets through large backing washers on the inside and then are soldered in place. While on the inside, the thin sheet air ducts, the transceiver mounting studs and small tabs for wires are soldered in place.

The breastplate follows a similar procedure; the collar ring is clamped to the shell’s edge and soldered into place leaving a smooth joint. The brales are clamped in place and the centers of their elongated slots are used to locate and drill the twelve, equally spaced, stud holes. The holes on the inside of the breastplate are then countersunk for the 5/8 inch diameter heads of the studs. Then the studs are sweat soldered in place and the excess solder is removed on the top side with a special three fluted cutter. One stud, on the lower left corner of the breastplate (called the “bastard” stud) is slightly longer to allow mounting of the air control (belly) valve’s link and bracket chain. The lock stop’s recessed plate is soldered onto the back of the male neck ring using silver solder for strength. Then the ring is aligned and is soldered in place to the top of the shell. The breastplate’s eyelets are inserted into previously drilled holes in the shell, the heavy shaped washers are placed over the stud ends of the eyelets, on the inside, and the studs are peened over. Then the eyelets are soldered in place. The last step on the breastplate is adding a wire bead to the outer edge of the collar ring to facilitate sealing the dress gasket. The USN drawings specified a 1/8” half round brass bead, however, Ric suspects this was never used. DESCO uses 1/16” round brass wire and once it is soldered in place the solder is scraped along each side to form the requisite half round shape.  Now the helmet and breastplate can be cleaned and sent out for tin plating.


The final assembly begins when the helmet and breastplate are returned from electro-plating. The helmet arrives in matt silver tin plating (a USN specification). With all the add-ons in polished brass, this makes for a beautiful assembly. The guards for all four ports are held on with 4 each 8-32 brass screws. The faceplate’s pivot pin is inserted on the left side and is safe-tied with a brass cotter pin. On the right side the toggle bolt’s wing nut is spun on and its’ retaining washer peened over. Then the flat rubber gasket is added. The spit cock handle of polished brass is installed and its’ lapped fit checked.

Fastened to the right hand gooseneck is the non-return check valve. Straight forward in design the valve requires great care in assembly. The reason for the check valve is subtle but critical. Should the compressor or air line fail…without the non-return valve the greater pressure in the dress would try to escape up the hose to lower pressure. This will, in effect, try to force or “squeeze” the diver into the rigid helmet and will result in serious injury or death. The non-return feature prevents this from happening. As little as one-fourth p.s.i. air line pressure will open the check valve and flow air into the helmet but when the pressure drops the valve closes promptly. The non-return valve design was changed by the US Navy in the late 50’s or early 60’s from a multi part spring/stem and leather seat arrangement to a body utilizing a standard check valve cartridge made by Kepner Products Company. DESCO’s current non-return valves are of the later cartridge style. This valve should be tested before every dive. It is easily assembled and disassembled for regular inspections. The protective caps for the gooseneck fittings, sealed with leather gaskets, are an added necessity.

The transceiver is installed in the recessed cup with four nuts and its’ cable is routed along the inside the helmet and held by the copper clips. The end of the cable attaches to the original plug’s fittings in the telephone gooseneck and is filled with bees wax to make it watertight. The internal cable opening is sealed with flax packing and a compression nut. This prevents water from following the exterior cable into the helmet. However, should the customer want to use a modern communications box and plug assembly, such as the Marsh Marine connectors, the cable passes from inside the helmet, through the gooseneck and through a special packing gland built into the brass sealing cap. Other connections can be made depending on the customer’s needs but must be specified when ordering the new helmet.

The exhaust valve pieces are assembled with both the light primary and secondary valve springs. When the pressure increases in the dress, above one-half p.s.i., the stem seat raises against the light primary spring, letting air escape automatically, and thus maintaining that pressure. Manually, the valve seat and internal pressure can be increased by up to 2 p.s.i. by screwing down the external star shaped hand wheel against the heavier secondary spring. The internal chin button is part of this assembly and can be activated to dump the internal pressure when the diver’s hands are busy. The external parts of this valve are hand polished and add a striking contrast to the silver helmet. 

At the rear of the helmet the dumbbell’s polished safety latch gate is riveted to the recessed lockstop on the back of the breastplate and its’ safety chain is attached by a brass loop.  Its’ three sixteenth inch split pin is retained by the short brass chain. The polished brails and retaining wing nuts are assembled on the breastplate with four thin copper sheet washers that keep the ends of the brails from pinching the rubber flange of the dress.

The final fitting of the leather neck ring gasket is time consuming. To cut the gasket ring a piece of leather is tacked down to a board on the drill press and a special cutter trims the outside diameter. Next the center is tacked down and the center circle is cut out. Currently, DESCO buys the gaskets from a leather shop. The specification for the height of the neck ring gasket on the USN drawings is 3/16” to 7/32”. Since cowhide varies in thickness some fitting of the gasket is required and is done by scraping the surface of the gasket with an appropriate tool. The gasket is reinstalled on the breastplate and the top is screwed on. High spots will be shiny on the scraped gasket and the distance between the index marks noted. The process is repeated until the desired fit is achieved. On helmets used for diving the fit will tighten as the centering marks align. Creating a watertight seal is the primary concern in this case. On display helmets the gasket may be trimmed a bit more allowing the alignment marks to pass by an inch or so. With time and weather changes the gasket will swell bringing the marks closer into alignment and the extra clearance makes it easier for the customer to assemble the helmet to the breastplate.

DESCO Air Hat production

Installation of the nametag to the front of the breastplate is the last step for completion. The brass and black enameled Navy tag is riveted below the eyelets with the serial number and date of manufacture stamped into the spaces provided. The date of manufacture will be the date the helmet is completed unless a special date is requested by customer. A requested date must be near the actual completion date and usually commemorates a birthday or retirement date. 1/8” copper round head rivets are inserted thru the tag and breastplate shell, trimmed to length and peened over. Then a small dab of solder is added to each rivet on the inside to waterproof the hole.

This work of art, a complete MK V helmet and breastplate assembly, takes about 160 hours to complete.

NOTE: This information is for educational and historical purposes only and is not intended as an instructional guide to helmet manufacture, repair or use as a life support system. Diving is an inherently dangerous operation and diving helmets are considered life support systems to be used or worked on by trained personnel only. Any use of diving equipment can and will cause injury and death. DESCO does not authorize the use of this material for anything other than armchair enjoyment.

Please help us assemble a record of DESCO helmets in an effort to recreate some of our production records and fill holes in the information we currently possess. This can be any DESCO helmet, of any type currently in existence. This information will help us authenticate helmets as their serial numbers and dates of mfg. should be consistent with our records. The data we need is the manufacturer, helmet type, serial number, and date of manufacture. Additional info like current owner and location is desirable but not necessary. The info can be e-mailed to us at or It can be faxed to 414-272-2373 or mailed to 240 N Milwaukee Street Milwaukee, WI 53202

Links to other diving online articles

SS Westmoreland Salvage attempt by Jack Browne & Max Nohl in 1936  Michigan Mysteries website

Max Nohl diving bell for Silver Springs Milwaukee Journal article January 21, 1940 found on google news

Life of Max Nohl Milwaukee Journal article February 6, 1960 found on google news