MALM FROGDIVER 44
DEVELOPED TOGETHER WITH SWEDISH FROGMEN. IT’S A ROBUST, SWEDISH DIVE WATCH DEVELOPED TO WITHSTAND HIGH MILITARY REQUIREMENTS AND STANDARDS.
The new Frogdiver project began in the autumn of 2019. It is an ambitious project and initiative between MALM and members of the 44th Mine Clearance Division whom are a part of the 4th Naval Warfare Flotilla in the Swedish Navy. The main objective of this project is to develop a robust and reliable dive watch completely based on the experience of the Swedish frogmen and their requirements.
Frogmen where introduced in the Swedish Navy during the 1950’s under the management of captain Rolf Hamilton. Their main mission was to clear mines and ammunition below the surface which had been left behind after the end of WW2. Today their operations are much larger and wider than that with several international missions to clear mines on land, areas between land and water and far below the surface.
The name FROGDIVER 44 is a nod to the term “Frogman”, the common name for naval clearance divers. Number 44 suggests both the size/diameter of the watch case as well as the 44th Mine Clearance Division participating in this project. The FROGDIVER 44 is, apart from the Swiss automatic movement from Sellita, designed and developed from scratch by MALM and the divers. The watch combines details from both previous and new scuba gear equipments together with heritage and inspiration from the divers organization. All details are interpreted in high-performance components and functions with shapes, colors, and materials chosen to withstand the tough conditions in the cold and dark Swedish waters.
Analogue depth gauge
Capillary tubes are a well known analog depth meters in the world of diving. They are based on the principle of the Boyle-Mariottes law, has no moving parts and consists of a simple tube that is opened in one end and sealed in the other. While diving and descending, water enters the tube and creates an air bubble that moves inside the tube when pressure changes. Current depth is read by studying the position of the air bubble on a provided scale - a simple solution that may not be particularly accurate, but very durable and reliable.
A capillary tube and depth gauge like this has been installed and milled in to the solid steel of the FROGDIVER watch case. The water enters through a drilled hole in the sapphire crystal and lead into the tube starting at 9 o'clock position. While descending in water, the pressure changes and the air bubble is pushed through the tube clockwise. Connected to the tube there’s a scale showing the current depth that the diver can read. This simple yet innovative solution has been developed by MALM in consultation with the Swedish frogmen as a complement to their modern and digital depth meters.
The dial uses several features in order to supply its owner with the best possible readability in bright and dark waters. The dark background creates a clear contrast against the white second-indices that are printed with BGW9. 12 pcs of raised boxes have been applied with BGW9 and supplies bridges for 12 pcs of custom made tritium tubes which illuminates independently of any light sources.
In the watch dial there’s a thin, circularn mirror that enhances the readability of the second and minute hand. The mirror also reflects the lume effect of the tritium tubes and the BGW9 printed indices in the dark environments. The inspiration to this feature comes from one of the gauges of a recompression chamber called “Gullan”, used when the diver is affected by decompression sickness.
LUME & TRITIUM
A high level of readability is crucial when developing a mechanical watch made for dark and muddy waters. A common solution is to use various luminous materials printed or glued on the watch dial and watch hands. Luminous materials comes in a many different shapes, colors and nuances and performs on various levels in strength, glow effect and durability. Common for all lume is that it needs to be charged with a light source. For some a flash of sun- or daylight is enough and for others a close and strong light source, like a flashlight, is required to activate the luminous effect.
An alternative to traditional lume are so called tritium tubes. Tritium is a radioactive isotope of hydrogen (hydrogen with two extra neutrons) and is well known in the world of watches for its ability to glow in the dark on its own without any light source. This is beneficial for divers because flashlights and other strong sources of lights can easily damage their natural night vision and greatly impair their visibility for the rest of the dive.
Tritium is, most often, produced by man and exists in a relatively instable form of gas that continuously strives to reach a more stable form, in this case an isotope of helium. It’s the process of decay from hydrogen to helium that generates the energy used to create luminous effects.
Tritium used in watches and watch dials are capsuled in small tubes sealed in glass. On the inside of the glass there’s a surface of phosphorescent paint that can absorb the energy emitted by tritium and release the energy as a luminous effect. Phosphorescent paint comes in many options, therefore it’s possible to choose the color of its glow. There’s also different qualities avaliable when using tritium tubes where higher quality often suggests that each glass tube contain a larger amount of tritium. Since its not possible to see the actual decay of tritium by eye, the quality of the phosphorescent paint is important in order to capture the larger amount of tritium and translate it into glowing colors. In that way, the amount of tritium and the quality of the paint are both of great importance when trying to create a strong luminous effects.
The tritium tube’s ability to glow by its own makes them very popular and usable in dive watches. Important to note is that the capacity and effect of the lume is decreasing after time, and after around 5-8 years the decrease is noticeable. You don’t replace the tritium tubes or “recharge” them in any way. Instead, the whole dial is needed to be replaced with a new one. All handling of tritium, from manufacturing, assembly, maintenance, stock and sale, requires a special permission provided by the Swedish Radiation Safety Authority and all tritium must be handled with care by an approved radiation safety function.