fbpx
Connect with us

Education

Maintaining Unit Cohesion

If you’re going to go metric or already are, it’s time to get your units straight, explains British tech instructor Rich Walker. Don’t mix your metrics, or your metaphors!

Published

on

By Rich Walker
Header photo from the GUE archives

For the past few years, I’ve seen a worrying trend when people are discussing gas management topics. It seems to be restricted to regions using the metric system, and in particular some areas of Europe.

Now it’s nothing that is going to cause harm, or be dangerous to divers in any way, but it is simply a factual error that is creeping into teaching, and even into an official scientific diving manual. I think it’s time we fixed the mistakes!

The problem relates to the units that are used when talking about the free liters of gas that are present in a scuba cylinder. For example, the amount of free gas that a 12 Liter  cylinder, pressurised to 200 Bar contains can be calculated as follows:

12 Liters  x 200 Bar = 2400 Liters         Equation (1)

Bar or Bar Liter? Photo courtesy of GUE Archives.

And here is the problem that has been spotted. If you multiply Liters by Bar, the resulting unit should be Bar Liters, right?

Wrong.

To understand why this is so wrong, and the correct unit is still Liters, we need to go back into physics a little. Think about how you calculate the amount of free gas that is present in a cylinder at a depth of 30 m/100 ft. We’re talking about taking the cylinder to a depth of 30 m/100 ft, and then releasing the gas. How much volume does it now occupy, (assuming it doesn’t all float away of course)? Let’s take the same cylinder as the above example. We’d make this calculation:

12 Liters x 200 Bar / 4 Bar = 600 Liters           Equation (2)

Mark your bottles clearly and know your gas management units. Photo courtesy of GUE Archives.

Nobody could argue that the correct unit for the result here was Liters. The mistake that people are making is that, in equation (1), they’re forgetting that they are also dividing by 1 Bar, the ambient pressure at the surface. Now dividing by 1 doesn’t change the result, but the Bar unit of the “1” is important as it keeps the result dimensionally consistent, to use the mathematical terminology. If we rewrite equation (1) properly, you can see it for yourselves:

12 Litres x 200 Bar / 1 Bar = 2400 Liters         Equation (3)

So there is no such thing in diving gas management as the Bar Liter. Let’s stop using it!

You can also watch the video in German.


Rich Walker learned to dive in 1991 in the English Channel and soon developed a love for wreck diving. The UK coastline has tens of thousands of wrecks to explore, from shallow to deep technical dives. He became aware of GUE in the late 1990’s as his diving progressed into the technical realm, and eventually took cave training with GUE in 2003. He began teaching for GUE in 2004. Walker is an active project diver, and is currently involved with the MARS project in Sweden, and cave exploration in Izvor Licanke, Croatia. He is also chairman and founder of Ghost Fishing UK. He is a full time technical instructor and instructor evaluator with GUE, which he delivers via his company, Wreck and Cave Ltd. He sits on the GUE Board of Advisors, and several other industry bodies.

Community

Finland’s Newly Established Scientific Diving Academy

Published

on

By

by Edd Stockdale
Header image: Antarctic research as part of Science Under the Ice project Photo by @scienceundertheice.

While exploring the aquatic realm, many divers often encounter objects of interest but are unaware of the historical or scientific value to the fields of archaeology, geology, or biology. Even if they suspect their find might be important, they are untrained in how to treat such a find with an investigative approach.

Scientific diving, separate from sport, recreational, or commercial diving, requires occupational training specific to science-led, underwater activities with the purpose of collecting data and/or samples. This type of diving is important both to research, as well as to policy making, because divers with this specific training and background can make the quantitative or qualitative-based assertions necessary to implement the findings. There is a necessary and important distinction between professional scientific divers and the “citizen science” trained divers who are essential in building public awareness, particularly in conservation projects. 

The necessary training and the regulation of professional scientific diving varies widely from country to country, both in regulation requirements, as well as in practice. In many countries, scientific work is classified as commercial diving, and regulations are set accordingly. At the opposite extreme, underwater scientific activity can be conducted by anyone certified to dive.

Structured approaches were developed to mitigate the abuses that both of these approaches might create—one such approach was specifically from the American Academy of Underwater Sciences, formed in 1977. AAUS, in 1982, received an exemption from commercial diving standards through self-regulation. In Europe, the process of establishing a recognized training standard was slower because many different European countries had different regulations; however, in 2007, after collaborative efforts by leading researchers, the European Scientific Diving Committee was formed. This agency became the European Scientific Diving Panel (ESDP) in 2008. ESDP established the standards for both Advanced European Scientific Diver (AESD) and European Scientific Diver (ESD) that are recognized by its member countries. 

One of the  early members in the establishment of ESDP, Finland, has experienced a decrease in scientific dive training options but no decrease in the demand for trained divers because of the increased amount of marine research and monitoring Finland carries out. To fill this void in suitably trained divers and to develop a new generation of marine researchers, a group of leading representatives from various institutions have successfully sought funding to establish a new, centralized training center—the Finnish Scientific Diving Academy (FSDA) at the University of Helsinki Tvarminne Zoological Station. FSDA is located on the shore of the Baltic Sea. 

Archeologist taking video for photogrammetry model of Garpen by Rikka Tevali, Photo by Finnish Heritage Agency.

The Academy’s primary objective is to train European standard professional scientific dive training for AESD certification, but this is far from its only goal. In addition to the six-week core program, plans are in place for adding dive training to undergraduate and early career research students to stimulate future generations of field-based marine researchers. Courses for divers who want to gain more experience or to develop skills for citizen-science-based projects with shorter timescales are also in the cards, making the Academy a truly centralized base for all aspects of scientific dive activities, one that can offer expertise across the disciplines.

With its location on the Gulf of Finland, this training will predominantly specialize in cold-water based approaches, though training options in other locations are always a possibility to cover different conditions. Taking advantage of the ice conditions in Finnish winter’s polar research dive training, which, combined with easier access and facilities already established, makes the option to train for polar projects—without the logistical hassle of actually getting to research stations in those regions—a realistic possibility. 

Included into the development concept of the FSDA is not only the concentration on classical scientific diving protocols, but also a widening the scope. It is often ironic that all the different areas of diving contain techniques that can overlap to benefit each other but are not taught or communicated; for example, skills used in a cave diving survey could easily benefit an ecological study or archeological field work. Therefore, the coordinator position for the FSDA requires a background in not just scientific, but technical and other areas of diving with the aim to integrate these skills into these areas into the programs.  

As a result, in the future, courses will likely be offered for specific evolving technological options, developing techniques, or specialist subjects that research teams need in order to carry out projects. Training may also be offered for more advanced diving, including mixed gas and rebreathers, to expand the ranges and environments to carry out scientific work. 

At the other end of the spectrum, driven by the growing need for more studies of aquatic regions combined with reduced funds for research, citizen science or the involvement of non-professional volunteers becomes more relevant all the time. 

Training options for divers looking to develop these skills vary dramatically, and they may not be familiar with research institutions where expertise is highly appreciated. 

Due to the need for scientific consistency in work carried out, divers not only need high levels of diving ability, but also an understanding of the project goals that are important for the results to be valid. Such training is specialized, but done and implemented correctly, provides scientists with the resources of capable dive teams, which is one of the long term goals of the FSDA. These programs will also aim to cover more specialized fields of study or the application of different diving procedures, both from the requirements perspective of project leaders looking for teams of “citizen scientists,” as well as from the divers themselves. 



Overall, the creation of the Finnish Scientific Diving Academy is exciting for both the scientific and regular diving communities, as it aims to address reduced access to specialized training while developing newer techniques and raising awareness of the importance of how research into the marine world is carried out, whether it is surveying a 400-year-old shipwreck or the ecology of a reef.

The FSDA has been initially funded by the Antero and Merja Parma Foundation and Weisell Foundation for three years with aims to secure more funding to remain long term and is coordinated by Edd Stockdale. The first courses will begin in April 2022. Queries should be sent to Edd Stockdale


Edd Stockdale has worked in scientific and technical diving for over a decade and joined as Badewanne team member in 2019. He is the coordinator of the newly established Finnish Scientific Diving Academy at the University of Helsinki, which was established to develop scientific diving training to further research abilities and develop new approaches to data collection in cold water based science.  When not working on research diving, Edd can be found exploring the mines and wrecks in the Nordic region or planning the next adventure. He is supported by Divesoft as well as Santi, Halcyon, and REEL Diving in Scandinavia. 

Continue Reading

Thank You to Our Sponsors

Subscribe

Education, Conservation, and Exploration articles for the diving obsessed. Subscribe to our monthly blog and get our latest stories and content delivered to your inbox every Thursday.

Latest Features