Another Dive Accident in Port Washington

[Vtach]

I doubt that anyone really exactly what events that caused his death were.  Here is what we can speculate through information on other forums. 

He was known to regularly dive a modified BMR 500 closed circuit rebreather possibly manually operated.
Pictures posted did not indicate he used a full face mask, bailout valve or heads up display on that unit.
He had previous experience diving beyond recreational depths with staged decompression on CCR.

Possible causes based on this information are numerous but I will list the ones that I feel are most pertinent

1. CCR operation related.
   a. Hypoxia - lose consciousness, lose mouthpiece and drown.
   b. Hyperoxia - start to seize, lose mouthpiece and drown
   c. Hypercapnia (scrubber failure) - become disoriented, lose consciousness, lose mouthpiece and drown
   d. Loop failure (caustic cocktail) - airway irritation, coughing, choking (if bailout not easily accessible drowning is likely)
2. Medical
    a. heart attack, pulmonary embolus, stroke (cerbral embolus), etc....

A manually operated closed circuit rebreather relies on the diver to maintain the setpoint or level of oxygen in the breathing loop.  If it is too low (hypoxia) or too high (hyperoxia), the above problems will likely happen.  Once unconscious and the mouthpiece is lost, it is highly unlikely to get it back in.  At those depths the diver will need (for the most part) to be self sufficient and manage problems on their own.  A buddy may be able to offer minor assistance with additional gas supplies or minor equipment problems but once things transgress to the point of impairment, a buddy would have great difficulty in "rescuing".