This is something that is widely variable from person to person, from diver to diver, and can ebb and flow based on the current state of affairs, and even day to day state of mind. Earlier this week, while conducting a fairly routine activity underwater – fully accepting the risk – I was left literally hanging in the balance…and there I was.
To set the stage, we were out doing our routine mooring work. For those not in tune with mooring work, it means alot of diving in muddy harbors, lots of ups and downs, humping around heavy chain, breaking old rusty shackles in poor visibility, and generally breaking your back day after day. Why do it? Well, it’s some of the best dive training around – you dive long and hard, have to trouble shoot continuously, have to deal with rigging issues repeatedly, and are forced to work in the dark. To the latter, one’s situational and spacial awareness becomes acutely dialed in, and in my opinion, once in dive shape (both physical and psychological) from mooring season, you are in dive ready shape for just about anything.
The day’s task – recover a 1000 lb train wheel which was used as a mooring anchor, and relocate it to another spot. So, this involves using lift bags to float the 1000 lb of dead weight, and then re-sink it at a new location. The diver is responsible for rigging up the bag securely, directing air in/air out, and ensuring this occurs in a controlled manner so as to not injure him/herself, the boat, or damage the equipment. We use lift bags routinely, moving moorings and even recovering sunken vessels to the tune of ten tons or more of required flotation. In this case, we went for 2000 pounds of buoyancy (2:1 over the object) for some added insurance that she’d sit high during the long tow to the new spot.
So, where did things go wrong? Well, I had the trainwheel rigged up (mind you we were only in about 10 feet of water), and we started adding air to the lift bag. Once we were at about 50% of required buoyancy to lift the wheel off the bottom, I surfaced to grab what would be the tow line. I then dropped back down and leaned in to tie the tow line in to the train wheel. As I did that, a toggle from the dump valve on the lift bag got caught up in the yoke from my first stage regulator on my back. As I attempted to back away from the train wheel, I was stuck. My hard earned diver instincts kicked in – I made one quick attempt to free myself by hand, and when unsuccessful, I quickly grabbed a knife and cut the toggle away. This all happened in less than 3 seconds. But, during those long three seconds, there I was hanging in the balance…
Had the lift bag failed and ruptured, I would have been stuck to a 1000 pound object on the bottom. Had any of my rigging failed, I would have been shot to the surface while attached to a 2000 lb liftbag, surely to suffer an embolism. Risky? Well, it depends on that level of acceptable risk.
The take home for me was to start thinking harder about alternate gear configurations for these types of projects. I have been thinking about sidemount configurations for working scuba dives for this very reason, and this may have been the impetus to take a closer look at doing this more routinely. The other take home was to ensure that I always have redundant cutting devices. I always have one knife, but one should never take for granted that “just because its shallow” that’s enough. If I hadn’t had a knife, or it broke, I would have had to remove my tank to clear the toggle – adding to the stress and time required to clear myself of the entanglement.
Back on acceptable risk – I’ve used big lift bags hundreds of times without incident and honeslty never thought much about a dump valve toggle entanglement – the chances are so minutely slim that I would argue this is acceptable risk. Driving home that day, I drove past a 3 car pileup that scared me far worse, and left me second guessing our entire transportation system…get it? Risk is relative, and just because an activity is foreign to the masses, does not mean it is foreign to those entrenched in the trade. This is where it is critical to educate those around you – regardless of the risks (perceived or real) being undertaken such that those across disciplines or sectors can work together, rather than just squawk and make more bumps in the road. It’s the bumps in the road that cause those 3 car pileups, not responsible tradesman who are expert in their field.