ORGANIC GLASS DIVING HELMET

Many thanks to PAVEL BOROVIKOV (The author of the book ' Diving Affairs of Russia') for sharing MP Shikanov's article and the photos of the Plexiglas helmet.

Subsequent to the introduction of underwater electric welding and cutting in ship salvage , bridge building and general hydro engineering works, it was found that metallic , i.e. copper and steel diving helmets and their breastplates were liable to electrolysis especially when working in the sea with electricity for cutting and welding. It resulted in the deep corrosion of the helmets and their rapid degradation. In some cases, should a careless diver touch the helmet with an electrode there could even be burn through in a helmet.

Experimental work on other types of materials lead to various ideas including an electrolysis proof coating such as tin and the development of materials not traditionally associated with helmet building. One of these materials was Plexiglas (organic glass) which was being used for many applications both in the home and throughout industry. Plexiglas is a complex chemical product with hard but colourless properties. It could be drilled , polished, turned , machine cut and was chemically inert. It was found to have great mechanical strength and good dielectric properties. Plexiglas has elastic properties when heated above 80C and can be bent and moulded into shape. When cooled it retains its shape.

Plexiglas is highly transparent when polished, however it can be scratched by sharp objects and is flammable. Despite these faults it was used to build diving helmets because of it's resistance to electrical currents and its transparency. It also afforded the diver great all around vision. The first experimental helmets were made from sheet material as in the USSR limited thicknesses only were available. The sheets were heated up in a water bath to 80C and the using a mould and a press the semi -sphere was formed. Two semi spheres were then prepared and they were bonded together with a special glue. The finished helmet was then presented to expert engineers who acknowledged the positive qualities of the helmet.

It was found however when a helmet was dropped it would crack and some experts felt that the fragile nature of the Plexiglas meant the work would cease as the helmet was impractical. The time frame around when this work was being carried out was during 1944.

At this time the work force of The Narkomkhymprom ( the Peoples commissariat of the chemical industry) suggested they may be able to help with the problem of the fragile nature of the Plexiglas which was being used at the time . It was their belief they could produce Plexiglas which was capable of withstanding a heavy impact. There were new tests and experiments and early in 1945 near Moscow one of the Narkomkhymprom factories built a new experimental model made from 1/2 inch (12 mm) Plexiglas with a reinforced seam. Reinforced ribs were glued to the outside top surface and conventional bronze air fittings were mounted with rubber washers on the sides.

The helmet was now used in experiments at Balaklava (Sebastipol) where it passed rigorous underwater tests . Divers using this transparent helmet cut holes in metal,
washed mud by water jetting, bound ropes and inspected sunken objects. The helmet resisted the rigorous ardurs of the underwater work and despite being covered in scratches it resisted all the impacts it received. To test its durability an experienced diver intentionally impacted the helmet at depth. Despite a crack of 2 inches the helmet's integrity remained intact. The Diver returned to the surface and declared a metallic helmet would not have withstood such a blow.

The advantages of the Plexiglas helmet were:
1 The helmet has total resistance to electrolytic action.
2 Has all around visibility
3 There is no condensation as Plexiglas is a good insulator against cold temperatures.
4 Improved acoustic capacity due to the good sound insulation properties.
5 Provides a good teaching platform as the transparent nature of the material allows the instructor to check on the student's face and expression.
6 The material is not liable to corrosion in salt water.

There were however some drawbacks:
1 There is a distortion of the divers field of vision due to the spherical shape of the helmet's dome.
2 The polished surface could easily be scratched , especially during water jetting operations. This lead to an impaired field of vision for the diver.

The 6 th department of the GVRU ( Main Diving Repair Office) developed certain specifications after reviewing the drawbacks. Helmets were made with the following modifications:
The front viewing area had a flat part in the form of a circular window which eliminated the distortion.
The helmet was to be fitted with a device for bonding a protective tape on the field of vision on the outside of the helmet. The tape was then to be removed as it wears, thereby protecting the surface of the Plexiglas.

GRVU ordered 100 experimental 12 bolt models with their breastplates being made of organic glass.
They were to be made in one of the Narkomkhymprom factories. They were to be supplied to various departments of the GVRU in 1946.

They were then to be tested by the different departments and reports made to the GVRU of the results.

This information was published in 1945 by:
Lieutenant Commander MP Shikanov
Translated by: Konstantin Korchagin
Corrections by: Denis Dubovoy
From the Dive Club 'Sadko' Nikolaev, Ukraine 2007.

The Translator has made the following observations:

1 We presume the helmet wasn't produced for regular diving use as it isn't mentioned in any subsequent literature.
2 In a source not revealed it is stated a diver may feel psychological discomfort whilst working in a transparent helmet as he would be subject to distraction occurring outside the diver's normal field of vision .
3 A helmet of Plexiglas construction in the photos below is attached to a copper breastplate but there is evidence to suggest from the earlier report that the original helmets were mounted on a Plexiglas breastplate.
4 Soviet divers were equipped with other plastic 12 bolt helmets similar to the DM 200 and DM 220. Evidence is currently being sought for the existence of such helmets.

With special thanks to Konstantin Korchagin

Dive Club SADKO, Nikolaev ,Ukraine.

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