How Did the Maker of Sharkwater Die?

Filmmaker Rob Stewart won more than 40 awards for Sharkwater, his 2007 documentary on shark conservation . It was at Alligator Reef near Islamorada, FL, where Stewart, 37, met his end . He went out on the MV Pisces to make closed-circuit rebreather dives around the Queen of Nassau wreck on January 31 with his buddy, Peter Sotis. Both surfaced after the third dive, but while Sotis survived, Stewart did not.

The autopsy report obtained by media last year notes that both men ascended from the dive at a greater-than-normal rate, but the examiner ruled out decompression illness because dive crew successfully treated Sotis with oxygen, and he fully recovered . That would not necessarily have been the case with DCI . Oxygen is usually administered in cases of DCI, but it may not completely resolve it.

In the witness statement he made on the day of Stewart's death, David Wilkerson, captain of the MV Pisces, told the Monroe County Sherriff's Office that approximately 30 seconds after boarding the boat, Sotis became incoherent . "Stewart was around 10 feet behind the boat [in the water], waiting to board . He did not respond to commands to grab the [tag] line, and this is when I observed he had possibly become incoherent . I repositioned the boat to get the line to Rob immediately, at which time he had disappeared from the surface ."

The Miami Herald reported that Coast Guard officials finished their report about the incident last December . However, a Coast Guard official in Washington, speaking on background in late July, said the agency is at least six months off from making the report's findings public.

Since both men were diving with identical rebreathers using the same gas mixtures, the autopsy report concludes they both likely suffered the same condition . The probable difference is that while Sotis suffered his collapse when boarding the dive vessel, Stewart had his while still in the water . The medical examiner's report concludes that Stewart suffered an acute case of hypoxia, or lack of oxygen, which led to a shallow-water blackout . This caused him to lose his breathing loop and sink, which begs this question: Why was his wing not inflated so that he floated at the surface? Could this be the answer?

A trusted source with knowledge of the investigation and the ensuing legal action (Stewart's mother, Sandra, has filed a wrongful-death lawsuit) told Undercurrent that the medical examiner's report is inaccurate because Stewart's close-circuit rebreather's electronic 'black box' was never looked at . When later checked by those who had access, it tells a different story -- hypoxia was specifically excluded by the data recorded . Our source also says the Coast Guard's delay in publishing the information is causing unnecessary delay to the legal process.

As I've written here before, familiarity can breed contempt . Rebreather divers breathe recirculated gas from separate supplies of oxygen and of diluent gas (in this case, tri-mix) via counter-lungs in a 'closedcircuit .' This reflects the action of their own lungs . The unit automatically keeps the partial pressure of oxygen constant in the breathing mixture of gases . In this way, the diver actually uses less oxygen at depth, but needs increasing amount of oxygen in the mix he breathes as he ascends to shallower depths . The unit automatically adds oxygen to the closed circuit as the diver ascends . This tends to inflate the counter-lungs.

Confident rebreather divers can still come to the surface with counter-lungs inflated, meaning they will float comfortably without resorting to their BC . If they close the mouthpiece and then breathe fresh air, I suppose there's no problem floating in that way . Other divers keep breathing from the unit (which is part of regular rebreather training), but if they turn off their oxygen supply before getting out of the water entirely (not part of CCR training) in a misguided effort to save gas, or if they were low on oxygen because they squeezed a third dive out of one tank fill, hypoxia and unconsciousness could be followed by loss of buoyancy as the mouthpiece falls from their mouth . It could occur almost within seconds, and, without the separate BC inflated, drowning is inevitable.

Whether this was actually what happened or not, one could easily imagine Stewart doing something similar before he sank and died.

Sandra Stewart filed her lawsuit in Broward County Circuit Court demanding a jury trial against several businesses and people involved in her son's fatal dive . One of the defendants is the company, Add Helium, which was in charge of the dive, sold the rebreathers used by the divers -- and is owned by Sotis .

- - John Bantin