Dive Computer History – From Analog to Digital
Many technical advances have come from military needs. Dive computers are not different. The Navy needed a reliable system for their underwater warfare. They met in 1951 with the Scripps Institution of Oceanography in California. The requirements the Navy had was to get a device that reliably monitors the nitrogen loading in the body of divers.
The goal was then as it is today to replace the dive tables with a reliable monitoring device that tracks the nitrogen in the body based on time, depth, gas mixture and previous dives. While this capability exists today in devices that can even be worn instead of a wrist watch, they were pretty much unachievable in the early 50’s.
Scuba Computer Calculations
Nevertheless, two researches at the Scripps Institute published a paper that outlined the requirements and functionalities that such a device would need only two years after this initial meeting. Their requirements were that such a dive device would need to take two things into consideration:
- Decompression during the current dive
- Remaining nitrogen in the body from previous and current dives
Based on this it would calculate an optimal, in many cases faster, rate of ascend. They suggested that an analog device would be used to measure the decompression and the air consumption and then correlate those measured values to calculate the ascend rate. Don’t forget that this was outlined at a time when computers were anything but reliable, cheap, small or even digital.
These first set of requirements lead to the development and manufacturing of the Decomputer Mark I by Foxbory Company. It was evaluated by the US Navy in 1957.
It was an analog computer that informed the diver with the help of a needle whether the ascend was too fast or not. The device unfortunately did not work as expected and did not calculate the decompression status correctly. The Navy gave up on the computer and continued to use their own dive tables.
SOS Decompression Meter
In 1959 a mechanical analog dive computer was presented. It was developed by two Italians, DeSanctis and Alinari. The brand to introduce the device was SOS. It was intended to be a decompression meter/monitor for recreational diving. Other companies, like Cressi and Scubapro, started to also distribute the device.
It is not hard to imagine that in 1959 technology was not as small as today and also not as reliable as today. The device being mechanical required quite a setup of components. While the principle was simple, the design and the components weren’t.
The following years saw more and more mechanical analog computers be introduced. They all worked on similar principles as the SOS device and used bladders and membranes to simulate nitrogen absorption into the tissue. None of those really did the trick though.
SOS Poseidon 5
In 1963 the Italian company SOS introduced the Poseidon 5. It was the first semi-mass produced pneumatic analog diving device. It was widely copied by other companies and, as the previous models, used bladders and ceramic membranes to simulate the absorption of nitrogen into the tissue.
The device was overall so unreliable that it was nicknamed ‘Bend-o-meter’. The US Navy advised against its use for recreational diving.
Tracor – First Electrical Decompression Monitor
In 1963 the first electro-mechanical diving device was introduced. It was the Tracor and was not a mechanical, but instead an electrical device. It used ceramic membranes with different electrical resistance to simulate the nitrogen absorption by tissue under pressure.
It relied on a constant temperature in the device which was maintained electrically through the use of two large batteries. In addition, it needed four additional batteries to generate a constant voltage and current. Unfortunately, the battery consumption was very high which resulted in short dive times. Additionally, the system temperature was not stable and this resulted in error rates that were quite significant.
The next significant development came in 1979 with the introduction of the XDC-1. It was a purely laboratory computer that looked like a cash register. The XDC-1 was a desktop computer that was connected to the diver with a cable which had a pressure sensor in it.
The follow-up model was the XDC-3. It was and is the first real dive computer that was capable of being taken into the water by a diver. The XDC-3 was sold around 700 times until 1982. The XDC-4 was an improved version that was capable to calculate based on different gas mixes. For most divers, or actually nearly all divers, it was too expensive to buy at that time.
Around the same time Dacor introduced the DDC (Dacor Dive Computer). It was the first modern device that showed all necessary key information:
- Max. Depth
- Dive Time
- Surface Time
- Saturation Level
The DDC was able to store information for repetitive dives and had a sensor to warn if the ascent speed exceeded 20 meters per minute. It also had a LED that warned if the non-decompression limits were exceeded.
Next Iterations of Digital Dive Computers
These first digital gadgets were kicking off years of rapidly improving technology. The year 1983 saw the introduction of the Orca Edge. It was a pretty clever device that used 12 tissue compartments to calculate ascent speeds. The underlying model was based on the US Navy dive tables.
It used a standard 9V battery which lasted up to 48 hours. However, it did not calculate ascent times and its seals failed at depths larger than 50 meters. Additionally, the manufacturer was only able to produce one device per day. Without those shortcomings it could and most likely would have been a huge success.
In 1984 the Decobrain was introduced. It was designed by the Swiss startup Divetronic AG. The Decobrain can be seen as the first recreational dive computer. It displayed all data that we expect from a modern dive computer. It calculated ascent times and included warnings for NDL and ascent speeds. It was even available as a build-it-yourself kit which made it reasonably affordable at the time.
Dacor introduced the Microbrain as the successor of the DDC. The remarkable innovation of this device was that it used a specifically designed silicone chip which worked faster and more reliable. In also required less battery power and it can even today still be found being in use.
Suunto Introduces the SME-ML
The Finnish company Suunto introduced their first dive computer in 1986. It was the SME-ML. It was a truly remarkable piece of technology that had all essential features that a modern dive computer has. It was even capable of storing 10 hours of dives. The dive log was available all the time for the diver.
The underlying model was based on the US Navy dive tables (9 compartments from 2.5 to 480 minutes). The battery could last up to 1,500 hours. The max. depth was down to 60 meters with a max. 30 minute decompression time per compartment.
The SME-ML had a very simple design and introduced Suunto to the mass market. All key information was available at once and it was particularly easy to use. It took Suunto another decade to become the leader in the dive computer market but the SME-ML certainly was the foundation for that success.
The Swiss company UWATEC hit the market in 1987 with their Aladin device. At that time it pushed nearly all competitors away and become one of the de-facto standard devices to be used by divers. It had a max depth of 100 meters. The recommended ascent rate was set to 10 meters per minute.
It was able to store the data for 5 consecutive dives and one could eventually find it used by more divers than any other dive computer at the time. It was a rather ugly and bulky and sported a grey casing.
New Technology – More Features
There basically has not been any radical change in dive computers since the late 80’s. Yes, the best modern scuba computers are smaller, more capable and certainly more reliable. This also allowed the dive computers to become more and more popular and today the majority of divers uses a dive computer.
However, the basic functionalities of these modern marvels of technology are still the same as their predecessors provided in the late 1980’s. Additional features that were introduced are calculations for different gas mixes, digital compass, higher capacity log books, air integration, etc. Some of these features can only be found on mid-level and higher end models like the Suunto D4i Novo.
It will be interesting to see what the future will bring with improved sensor technology and networking capabilities.