Berry L. Cannon was a civilian member of Team 1 on the US Navy's Sealab III. He was also an "Aquanaut" on Sealab II. The Sealab III habitat was sitting on the bottom at 610' (185M) off San Clemente Island, 52 miles (83 Km) off San Diego -- nearly three times deeper than Sealab II.
Cannon and Bob Barth were locked out to repair Helium leaks around electrical cables penetrating the Sealab habitat. Barth was working to open Sealab's entry hatch around 0500 when Cannon began to convulse.
This video shows the Sealab III Habitat, PTC, and the Mark IX semi-closed rebreathers. The problem that led to Berry Cannon death is shown around the 24:30 mark.
Barth struggled to save Cannon near the hatch with no success. He brought him back to the PTC (bell) with great difficulty. The PTC hatch was sealed after all divers were inside; the PTC was raised back to the moonpool, and mated to the chamber. Efforts to save Cannon continued in the PTC. Cannon was lowered into the DDC (chamber) where the medical team confirmed that he was dead after making observations through the viewports and conferring with the team inside. The decision was made to bring the body back to the surface in the outer lock while the rest of the team remained at depth in the inner lock. The body was returned to the San Diego Naval Hospital (Balboa).
News agencies reported everything from electrocution to a heart attack caused Cannon's death. Findings of the board of inquiry cited Carbon Dioxide poisoning as the official cause of death. One of several Mark IX semi-closed rebreathers was found to have an empty CO2 absorbent canister, though it was not known if that unit was worn by Cannon.
Hypothermia is a likely contributing factor, if not the causal factor. It is important to understand that the body was seriously compromised by explosive decompression and elapsed time, making an autopsy difficult.
The PTC was not heated and the water temperature was about 40° F (4.4° C) so the divers were very cold before getting the hatch open. Shirt-sleeve comfortable would be around 88° F (31° C) at that depth in a HeO2 environment. The hot water supply umbilical wasn't properly insulated or sized resulting in water arriving at the diver well under the requisite 2½ GPM (9.5 LPM) at 110° F (43° C). The "hot water" was so cool and slow running that Barth and Cannon didn't even connect the hose to their loose fitting suits knowing it would make them even colder.
Berry Cannon at the hatch of one of the DDCs aboard the USS Elk River, IX-501.
The Mark IX's breathing resistance at depth was very high by modern standards and the gas was unheated. Semi-closed systems were effectively abandoned after Sealab in favor of open circuit Kirby Morgan Band Masks and surface-based closed-circuit recycling systems about 15 years later.
The official findings were less than plausible to many divers on Sealab. The Baralyme Carbon Dioxide absorbent weighed 18 Lb (8KG). That much difference in weight would be noticed by the support crew and divers, especially after handling one with absorbent immediately after or before a "packed" rig. Even more important is the diver would notice being too buoyant as soon as they dropped through the hatch.
Berry Cannon Backgrounder
Berry Cannon was born on 22 March 1935, making him less than a month short of his 34th birthday on that fateful day. Cannon served in the US Navy as a Mineman, leaving after four years as Second Class Petty Officer (E5). He received his Bachelor's Degree in Electronic Engineering in 1962 from the University of Florida.
He designed communications systems at Navy Mine Defense Laboratory in Panama City, Florida, which led to assignment to the Sealab program. He spent 15 days saturated on Sealab II in La Jolla, California at 205' (62M) in 1965.
Cannon's funeral was held in Chula Vista, California, on February 19. He was buried at Wacahoota Baptist Cemetery in central Florida, while the rest of Sealab's Team 1 was decompressing aboard the Elk River. He was married with three sons.
Continued in the next post
