USN Mark V Facts

U.S. Navy Diving Helmet

Mark V Mod.1

SAFETY WARNING

NEVER, EVER DIVE A HELMET UNLESS YOU ARE ABSOLUTELY SURE IT IS GENUINE AND IN PROPER WORKING CONDITION. Replica helmets are not designed or built for actual use. Attempting to dive a replica helmet could result in serious injury or death. Only dive after you have received the proper training.

Warning to potential helmet purchasers.

Many replica Mark V helmets are currently on the market. These helmets often have authentic looking tags with the names of legitimate manufacturers on them. The most common replica has a "Morse" Diving nametag, and there is a replica around with a "Diving Equipment & Supply" nametag. The most blatant fake is one bearing a nametag which says "Brooklyn Navy Yard 1911". The Mark V didn't even enter service till 1916. People have purchased replica helmets believing they are genuine. When considering the purchase of any diving helmet do some research before you commit.

Some things to look for are the telephone cup set back on the helmet top. Copper sheet used to make exhaust banana tube instead of the real cast brass tube. The top window set too far up on the top. Window frames held in with screws. No ductwork inside the helmet. The top and breastplate held together by set screws instead of interrupted threads. Two piece air and communication elbows. A front door pin which is not removable. A "stove pipe' appearance to the breastplate instead of the rounded appearance of a genuine Mark V breastplate. The Spitcock stem is held in with a large round nut instead of a washer and hex nut.

"Morse" Replica Mark V "Diving Equipment" Replica Mark V

Here are some close up photos of the reproduction Mark V helmet we used to sell.

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A little about the diving helmet family.

Take a look at the Gallery page and compare helmet types

It has come into common usage to call any bonnet & breastplate helmet a Mark V. To a degree you can blame ebay and all the various reproduction helmets available there. The sellers often are not any more savvy than the average would be buyers and mislabel their replica helmets. All Mark Vs are diving helmets, but not all diving helmets are Mark Vs. The basic types of diving helmets are U.S. Navy Mark V, Commercial, Lightweight Commercial (Sponge), Shallow Water, and Low Volume. Low Volume helmets can be "free flow" or "demand". Just as an auto maker builds car models to fit particular customer needs, different models of diving helmets have evolved to suit different divers needs. Some helmet models are further modified to a particular divers requirements or the requirements of a specific job.

DESCO manufactured much of the genuine equipment used in the film "Men of Honor". The helmets used were not actual U.S. Navy Mark V helmets. The films production company chose to use a Commercial helmet top mated to a Mark V breastplate. If you look closely at the helmets in the diving scenes you will note the side windows are oval, and the front door is a screw in (Commercial) type. The Helium Helmet depicted was not a genuine Mark V Helium Helmet. It was made by the film company. Pay close attention to the front door assembly.

What is a U.S. Navy Mark V Diving Helmet?

Below are some things to look for in a genuine Mark V Helmet.

History

At the turn of the 20th century the U.S. Navy didn't have a standardized system for diving. The inventory of diving equipment in the U.S. Navy was a hodgepodge of various helmets, suits, pumps, and hoses by several manufacturers. Often as not pieces would not work together, making even simple assignments difficult. In 1912 U.S. Navy gunner G. D. Stillson submitted a report criticizing the way the Navy conducted its diving program. The Navy agreed and a group was formed in 1914 to standardize equipment and procedures. The original concept drawing is shown above. The Spitcock and Exhaust Valve are on the same side. The breastplate resembles a Commercial breastplate in the shape of the collar strap. In the 1916 U.S. Navy Diving Manual the Mark V Helmet first appears in its adopted form. The breastplate shape is unique to the Mark V being narrow across the shoulders and with a deep drop front and back. Some features remained from the concept helmet above with the exhaust valve on the right, a hinged front door, and air and communications elbows. The spitcock was moved to the left of the door, and guards specific to the Mark V were added.

All U.S. Navy Mark V helmets conform to a standard set of plans issued by the Bureau of Ships. Helmet shell, breastplate, all fittings and attachments are designed so regardless of the manufacturer all equipment would be compatible. Some small variances do occur between manufacturers but do not effect interchangeability.

Typical features of the Mark V Helmet are as follows:

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1. The helmet shell tapers to the neck ring. (Note: This rule is not hard and fast as some Mark V helmets were produced with a "bubble shell". Do not discount the authenticity of a helmet on this point alone.)

2. The front door is hinged and closure is with a toggle bolt. The hinge has a removable pin to remove the door, or attach a welding shield.

3. The Mark V helmet is fitted with round side windows and an oval top window.

4. The helmet has a air inlet elbow with a separate non return valve. Both the air and communications elbows are one piece, riveted and soldered in place with backing washers inside of the helmet. You normally cannot see the air inlet backing washer due to the ductwork inside the helmet.

5. The helmet has a communications elbow fitted to accept a standard U.S. Navy Communications/Lifeline.

6. The helmet is fitted with a telephone cup and speaker. The telephone cup has a shape specific to the Mark V.

7. The Mark V helmet has a double spring adjustable exhaust valve with a exhaust tube extending under and behind the right side window. The exhaust body (known as a banana exhaust because of the shape) is a one piece brass casting its entire length. The exhaust can be activated from the inside by the diver with his chin.

8. The helmet is fitted with a ball lever lock assembly. The ball lever pivots down from the top into a lockstop on the breastplate neck ring. The lock is closed with a latch which is secured with a cotter pin on a chain.

9. The Mark V Breastplate has a unique shape. It is narrow across the shoulders, and deep on the chest and back. The front and back are nearly symmetrical.

10. The top and breastplate are joined by interrupted thread neck rings. The shell makes a 1/8 turn clockwise to seal the connection.

11. The Mark V Helmet uses its own style wingnuts. The four wingnuts at the brail joints are flanged.

12. The Mark V helmet is fitted with 2 loops on the front of the breastplate.

13. War years Mark V Helmets used a exhaust valve made by the Batteryless Telephone Equipment Company. BTE will be stamped on the flat area of the exhaust handle. Later DESCO helmets uses our own 4 point exhaust handle which is rounder than the BTE.

14. A Mark V has a standard finish (specified by BuShips) of tin plating (silver color). Many Mark V helmets have been polished by the owners or specially ordered as polished from the factory.

Reconstructing history:

DESCO has been accumulating data on surviving diving helmets. We primarily focus on DESCO helmets but we also welcome information on other manufacturers helmets. Our purpose is to recreate to some extent the production record. Unfortunately records from DESCO's early period are all but non-existent. When a helmet is sent in for repair, comes up in ads, or online for sale we record the type, serial number, and date of mfg. We keep a list for our reference in cases where we are asked to authenticate a helmet. DESCO built helmet in batches during WWII and we check to see that the serial number and date fit onto the production schedule. A few minor anomalies have appeared but are explainable. Our list is far from complete. If you possess a helmet, or know of a helmet please submit the type, serial number, and date of mfg, plus any relevant additional information (i.e. modifications).

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