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Saturday, 26 December 2015

Do we really need to teach the controlled emergency swimming ascent anymore?

During entry-level diver training, the controlled emergency swimming ascent (CESA) must be taught. Experienced instructors hate teaching this skill for a number of reasons, first and foremost, the skill is outdated with modern equipment.


Secondly, when teaching big classes on a daily basis, multiple fast ascents is bad for you and thirdly, if a new diver can't remember to check their cylinder pressure, what is their chances of remembering the CESA procedure?
 

Then you have the logistics, a full class, no certified assistant and time pressures of a charter boat. You have to take each diver down individually while the other divers remain in view in a vertical column of water holding onto the ascent line as you can't leave uncertified divers in the water.

However, you have to leave uncertified divers on the surface unattended as you take each diver down the line but that is allowed - I would hate to have to defend that action in court.

Submarine escape training required specialised facilities, not only are specialist stand-by divers present, medical staff and safety equipment, a recompression chamber is usually on site for any diving maladies. Submarine escape training is required for all submariners and can also double for military divers.

The skill is a throwback to the days of military diver training, the equipment requirements today require the use of submersible pressure gauges (SPG) measuring the contents of the cylinder. No longer is the J-valve used, as such, divers no longer need to switch to the reserve to ascent to the surface.

For those who are unfamiliar with the J-valve, there was no SPG available to measure cylinder pressure and hence cylinder volume and as the cylinder emptied, it became more difficult to breathe from the tank informing the diver the cylinder was close to empty, the valve was moved allowing unhindered breathing for the ascent.

The SPG measures the exact contents of the cylinder, during confined water training sessions, that is an exercise that must be taught so that newly certified divers take responsibility for their own gas usage. 

Correct training techniques include the diver monitoring their own cylinders and not the instructor checking the contents of their cylinder. With modern equipment and training techniques, there is no longer a requirement for teaching the CESA and the skill should now be relegated to diving folklore.

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