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The miracle of the #deepseachallenge

We like many others have been following closely the progress of the James Cameron, National Geographic Expedition to the worlds deepest Marine Trench. We are particularly keen to see all that is going on as a former member of the team, and underwater videographer  Nick Corkhill is part of the crew assisting him to make this historic journey.

If  you, like many, are unsure quite why this is such a momentous feat, Nacho El Garasha has gone someway to try and explain the task.

The miracle of the #deepseachallenge

James Cameron’s plunge to the bottom of the Marinara’s Trench is a vast leap forward, or down, in so many ways.  It is remarkable in many ways that the math’s behind it will lose people easily and they will not appreciate how difficult this must of been.  What we are going to do is break it down to the simplest way to see how remarkable this #deepseachallenge is.

Let’s look at the numbers behind this expedition.  The Marinara’s Trench is 11,033 meters deep so the pressure there would be 1,104 atmospheres, ata, 1,103 plus the 1 on the surface.   The average adult male’s lung capacity is 6 liters; imagine four 1.5 liter water bottles.  Take those 4 bottles line them up and look at how much air is in your lungs.  Now take off one of the caps, that cap would be your lung size if you were to experience the pressures without SCUBA equipment, say free diving to that depth.  6 liters /1,103 the atmospheric pressure = 0.0054 liters

So the average male has a surface breathing rate of 17 liters per minute.  In order to dive to 11,033 meters, 1,104 atmospheres, that diver to compensate for the increased pressure, remember with every breath your lungs fill up to the same volume, you would be effectively breathing 18,751 liters per minute…  17 liters per minute x 1,104 the pressure at depth = 18,768 Surface Air Consumption Rate.

Now on to the tanks worldwide the most popular tanks are those 11 liter volume aluminum tanks that everyone has seen and hopefully used.  Lets assume that you are going to fill those to 200 bar as we do daily.  So an 11 liter tank volume x 200 bars of air = 2,200 liters of air in each of those tanks.  If you were to breathe for one minute at the depth of 11,033 meters how many tanks would you need, you ask???  Well lets take your SAC Rate of 18,768 liter per minute and divide that by your tank capacity 2,200 which gives you 8.53 tanks needed to complete one minute of breathing at 11,033 meters assuming that you were to exhaust everyone of those tanks without any redundancy, DO NOT TRY THIS AT HOME.  Essentially you would be finishing a tank every 7 seconds.

Please note this does not involve travel times to get to the bottom which took James Cameron over an hour plummeting at nearly 150 meters per minute.  Also not included is the accent times which Cameron’s sub did at the break neck speed of 150 meters per minute which would turn a diver into a can of soda, think of shaking up a can of soda and throwing it against a wall, splat, or your volunteer “Joe” diver.  Sure it would be an interesting experiment but terribly lethal to “Joe”.  Even thinking of attempting this goes against all recreational safe diving accent limits of 9-18 meters per minute and technical diving limits of 3-9 meters accent time per minute.

Also excluded from these numbers are the facts that you would not be able to breathe off of that SCUBA cylinder at 11,033 meters because the ambient pressure surrounding you would be greater than the pressure in the tank.  You would need a tank pressure greater than the atmospheric pressure.  I have endeavored to keep it simple thus far.  Generally in recreationally diving we say that 1 bar = 1 ata, this is not exactly true it is actually 1 bar = 1.01325 ata.  So now take our dive to 1,104 ata and times that by 1.01325 to get the bar’s that we would need in the tank to allow us to take a breath, actually for our lungs to be able to expand to the ambient pressure.  We would require a tank with a pressure rating of at least 1118.628 bar’s which is slightly more than our 200 bar pressure tank is from earlier.  For this reason alone you would need a submarine such as Cameron.

All of that plus without the thermal protection of James Cameron’s little tube, the 110cm tube he was in, he would of came back to the surface as more of a “Cameron Sickle” from the extreme cold temperatures at the bottom of the ocean he would of experienced.

Just think about the numbers and you will see how unbelievable this was…  I have worked this out for 1 minute of breathing at depth, on the bottom, which of course is not possible without more minutes.  James Cameron spent two hours at that depth.  Absolutely unbelievable again!!!  This one is really easy, to figure out how many tanks, IF THIS WERE POSSIBLE AGAIN: take 8.53 tanks times 120 minutes and you would need 1023.6 tanks, once again remember changing them every 7 seconds!!!

So is it a miracle, great engineering or a bunch cowboy paving the way to the lost abyss???  It is a historic day for science.  I for one cannot wait for the next James Cameron movie…