Yesterday, while breathing Triox 25/25 at Dutch Springs, I had the chance to contemplate helium vs. air diving.
Recently, I had made 2 dives on the Jodrey with Trimix 18/48 (final analysis shooting for 18/45) to 161 feet. The week prior, I was diving Nitrox 32 at Dutch Springs filming a GUE Fundies class with a max depth of 30 feet. The week after the Jodrey, I was diving to 80 feet in Bermuda on air, and yesterday, I dove Triox 25/25 at Dutch Springs teaching class to 90 feet.
Of these, the worst dives were dive 1 & 2 on the Trimix 18/45 to the Jodrey and yesterday's dive on Triox 25/25. Yesterday, I hit cold water after a week in Bermuda and was back in a drysuit, doubles, hood, argon bottle, stage, etc., so I just wasn't feeling into the groove despite the fact that mix helped me notice a few details about "my office" that I hadn't noticed before on the deeper sites. But, I'll share what I learned about deep diving from my recent dives based on experience.
The problem with diving the Jodrey was that on the first day, we had a team of 3 in which not all divers had been diving together prior to that dive. Added to which, we decided to take Gavin scooters. One diver teaches Gavins, the other just took his course, and the third (me) has only used a Gavin on 3 dives. I expressed my aversion to making a dive with an unpracticed team and with not having the ability to play with a Gavin the day before to get settled into the "feel" of that model scooter. But, the third guy in the team was willing to pay for the trimix if we scootered.
Note: Notice that this is much like deciding to "dial a high" in trimix diving when cost of helium dictates how impaired you will be regarding an END due to what mix you find acceptable. While we may have been on the best standard gas for a 160 foot dive, we decided to operate with the additional risk and complexity of possibly having to handle emergencies with scooters. This may not have been the wisest decision for inexperienced Gavin pilots who never worked together as a team prior to that dive.
A skilled team used to working together, and with many hours on the Gavin scooters, probably would have been safer and performed better at 160 feet on air or enriched air than we did on trimix that day. The gas certainly helped us. The selected handicaps didn't help us. While in shallow water, I made the call to thumb the dive based on scooters and the team decided to ditch the scooters. After the dive, the third guy in the team that wanted to scooter was happy that I made that call. Our ascent together was sloppy due to team communication. We also didn't have a solid deco plan so the team captain called it and we played followed the leader.
The second day, we still had good gas in our favor. We then had one dive together that helped assess the team's strengths and weaknesses. We left the scooters, came up with a better deco gas plan, but we took on the handicap of diving with a group of Canadian friends who arrived in their RIB. We had three teams of 3, 2 and 2 going to exactly the same spot on the wreck. It was the DIR version of a recreational wreck diving cluster. 3 cameras - video and still - blinding subjects with strobes and video lights, all divers looking identical, posing, smiling, profiling, losing buddy awareness, tight teams breaking into temporary or loose teams, and teams reforming. The good news was that we had good gas, standardized procedures, and the same exact training. Should something have gone wrong, we had the ability to fix it with anyone from any team. However, the lack of constant vigilant awareness could have placed a team member at risk of falling through the cracks of that awareness. More than once I truly believed my buddy was still right by my side only to discover it wasn't my buddy and that my buddy needed to be located. I decided to just stop my part in the madness and become the lifeguard by just staying put in one spot on the wreck so my two buddies could constantly reference me during filming and sight-seeing and I could watch everyone. The good part was that our deco went perfectly and we acted and moved as a team in textbook fashion. Until 20 feet, where we didn't have a plan due to leaving a second gas switch option open. That resulted in a board meeting on wetnotes.
Lesson: While decreased awareness and attention to safety is often blamed on air and narcosis, the lack of awareness caused by too many "same-same" divers with too many distractions such as the sort that occurs during filming, can create the same if not more dangerous, lapses in attention and reaction time.
Also, while those of us with training and experience with calculating deco on the fly, may elect to do so, much confusion and stress can be removed from a dive with a solid plan. One concern I have about new trimix divers is that they may believe they are bullet-proof on trimix and a moving target on nitrox and sitting ducks on air. It should be understood that the use of trimix does not remove a diver's need to place the same emphasis on dive planning and team familiarity that has been practiced by deep air divers to increase their safety when diving somewhat impaired. Two drunks with a plan may operate better than two sober people with a blurry strategy.
Conclusion: There is far more to safety when deep diving than just "narcosis management." While trimix is definitely an excellent tool to add to the equation of the planning and execution of any dive, it is not a magic formula for safety and performance. Divers must assess all the variables and parameters on dives to determine which ones will present the greatest problems for safety. Whether oxygen partial pressures, END's, decompression obligations, thermal issues, team experience, etc., each one becomes a vital figure in accident prevention and dive success. We stack the odds in our favor by balancing all potential threats, complications, standard procedures, benefits, and ad-libs on the scale of prudence.
