Publish Date: August 1995
ABSOLUTELY RISKY BUSINESS
August, 1995 – Though regularly conducted by a small number of commercial operators using saturation systems, diving to 1000 ft/307m is risky business. Only a handful of surface-to-surface “bounce'” dives have ever been conducted to these depths, and no one has ever done the dive on open-circuit scuba Not surprising; there are an extraordinary number of factors that must be taken into account in order to survive. Here are a few. as reflected in the Zacatón cable.
Gas planning is always a fundamental issue with scuba especially on deep dives. At 30—plus atmospheres, an aluminum 80 will only last a few minutes and small variations in breathing and/or descent/ascent rates can have dramatic implications. An unpredicted increase in gas consumption nearly cost Bowden his life on his this prior 94APR dive to 925 f/284 m. An extra 80cf stage cylinder saved it. Estimated gas consumption for the dive is nearly 1300 cubic feet. For his next
Attempt, Bowden plans to carry eight cylinders. and pre-stage the remaining cylinders needed so that he is able to abort the dive anywhere along the way down.
Then there’s oxygen. If the O2 levels are run too low, in-water decompression times become too long, making the dive impossible on scuba. Conversely. If they’re too high, the diver runs the risk of a CNS hit and drowning. The risk increases with physical exertion due to increased CO2 levels. The length of the dive also raises issues of whole body oxygen toxicity. Bowden is willing to tolerate short PO2s of up to 2.0 atm during gas switches, based on an ultra-low exertionrate and his and Sheck Exley’s past experience on extreme deep dives. [Technical community standards are to run oxygen levels at less than 1.5 atm during the working phase of the dive with a maximum PO2 of 1.6 during decompression, see ‘”Blueprint For Survival,” aquaCORPS N6. To increase his safety and comfort, he wore a full-face mask during his oxygen decompression on previous dives, and will use a decompression habitat or “microbell” next year.
Rapid compressions beyond about 400-600 f/123-184 m can result in High Pressure Nervous Syndrome (HPNS) producing tremors, nausea, and more. Sheck Exley experienced HPNS during his Bushmansgats dive to 863 ffvv/257 m. One solution is to run nitrogen revels as high as tolerable [See “HPNS” by RW Bill Hamilton, aquaCORPS N8] in order to ameliorate the effect, but how gooned do you really want to be that far down? Note from the table that there are numerous points in the dive where the “equivalent narcotic depths” (END) will be as high as 300 f/92 m. In addition to his prior mix dives at Zacatón, Bowden has conducted multiple work-up dives on air to 300 foot plus in order to test the effects of density on his regulators, build confidence, and condition himself to the high narcosis levels he is running. One atm practice with Johnny Walker Black Label may help as well. It is interesting to note that a shot of whisky was one of the first remedies for HPNS.
The risk of decompression illness is always an issue on tech dives. On his last dive, Bowden ‘”padded'” his table by switching back to his travel mix (trimix 10.5/50) from bottom mix (trimix 6.4/69.5 i.e. Heliair 69.5) at his first stop at 480f/147 m. and then breathed trimix 14/33 (Heliair 14) at 300 f/92 m until his first “air stop” at 260/ 80 m. This strategy was intended to boost O2 levels to improve decompression and to minimize the narcotic impact (and possible loss of consciousness) of switching directly from bottom mix to air at 260 f 180 m [Equivalent to an instant descent from about 60 f/18m to 260 f/80 m i.e. a massive bong hit. Bowden is concerned about the impact of the increased nitrogen he’ll be absorbing, but believes that it is more important to reduce helium levels ASAP. He then breathed argox 70 (70% 02, 30% AR) in place of EAN 70 at his 30f/9 m stop, and normoxic argox (21% O2, balance AR) during the swim out of the system, in an effort to maximize off-loading from both nitrogen and helium. Dehydration is also a surprisingly crucial issue on the ten-hour dive, “You just can’t drink enough,” he told me. And dehydration escalates decompression risk; hence, his plans for rehydrating with an IV while sitting cozy in the microbell.
Plan to bone up for that thousand-foot dive? Go hit the books. “I carry Bennett & Elliot [“The Physiology and Medicine of Diving] to the bathroom every night and read it over and over again,” Bowden confessed. “I like the fact that the authors remind you throughout the book, for those who are listening, that there are no absolutes.” Absolutely. You just can’t afford to have a bad day. ‘—Michael Menduno
Bottoming Out Zacatón
In April, 1994, Sheck Exley and Jim Bowden working under the auspices of Bowden’s organization Proyecto de Buceo Espeleologico Mexico y America Central, made an attempt to bottom out Zacatón, a cenote located on the El Rancho Asufrosa, in Northeastern Mexico. The two decided to dive on independent descent lines so as not to interfere with each other’s dive. The attempt ended tragically when Exley failed to surface. A gas shortage forced Bowden to turn his dive at 925f/276 m, giving him the world record but denying him at glimpse at Zacatón’s floor.
Here in this original August 1995 interview reprinted from aquaCORPS Journal #11 XPLORERS, Bowden discusses his motivation to make another attempt to get to the bottom of Zacatón.
People are going to read this story and think, oh my God, these people are crazy. I mean, Exley died doing this dive, Bowden got hurt, and now he’s going to go back and try it again. How do you respond to them? Is this a suicide wish?
There is no way you can explain it. So I don’t try. What’s the old saying: if you have to ask, you can’t afford it. No, I don’t have a death wish. I don’t really feel there is a career in deep diving, either. But I want to do it, and I’m working day and night to insure my safety as much as I can, and to insure that I can have a bail-out so that I can abort if it doesn’t work. I’m firmly convinced that if I had had the volumes [of gas] last time, then I would have done it, because my dive went very, very well.
All to bottom out Zacatón?
I’ve spent a decade and a half exploring caves. That’s my passion, all of every day. And a cave explorer wants to see the end of a cave. This one just happens to be vertical. And I think I can do it. If at any time I feel I can’t, well then, I’ll move on. You’re only as good as your last fight anyway. There are other systems I want to get into. But this is exciting, and I would not trade the experience.
I also don’t feel that this is the most significant thing I’ve accomplished either. I’m very proud of the Belize project and that was two solid years of living there, and my deepest dive was 46 f/14 m. I think it had every bit the dangers and excitement and drama; a lot more cerebral stuff and not as much time at the computer.
What aspect of the dive are you most afraid of, or that worries you most?
Having a bad day. Just having a bad day. I don’t think you can afford a bad day. That was Sheck’s reservation, too. When we first talked about doing this, and honestly, Sheck was the one who encouraged me to seek sponsorships ‘cause he knew my financial situation. And to seek sponsorship you have to seek exposure. Sponsors don’t do it out of the goodness of their hearts.
We also both agreed that we’ve seen the camera kill people. Sheck was too mature to fold to that, and that was not the case there. This next time, I’m really considering who I’m going to have there, or if I’m going to have anybody there. Like NBC, I’m sorry they weren’t there. They want to be there next time from what I hear. Can you imagine going up there and having that little gut feeling—you’ve had it haven’t you? Haven’t you pulled a dive for just nothing specific, it just doesn’t seem right? It’s better you do that with few media guys there.
Right, there is a pressure. Sheck wrote about that in Caverns. Just the whole pressure of saying, “Well, they’re here. Let’s just do it.” Have we reached the limits of scuba?
I think we are approaching it. Though some people would say that it’s already way passed. I don’t know and I don’t particularly care. When Sheck broke Hasenmayer’s record (656 ffw/195 m), nobody gave him a rat’s ass chance of succeeding. But he did, and then he went back and broke his own record.
Anything I would say in answer to your original question is subject to people wondering if that’s what I really feel. But I’ve already got the record. I don’t need to go break the record. And even if I break my own record, which I will with a successful dive—I’m confident will be successful—I really believe somebody will break it. And, yes, I think some people will die. Do I sound invincible? No, I’m not invincible, and no, I don’t have a death wish. I’m going to start a family when I’m eighty.
If I do reach the bottom, it’ll be the result of several months working on the perfect set, on correcting the mistakes I made last time. Then, if I don’t feel that I can, I won’t do it. I really don’t have anything to prove. I just would like to see the bottom of Zacatón like somebody would like to see, I don’t know, the dark side of the moon or whatever. I just would like to see it. It’s a personal thing. And if that’s a shallow desire by other people’s standards, well, so be it.
Bowden made two more sub 500 f/152 m dives in preparation for the big dive and was forced to abort several attempts due to equipment problems with a decompression habitat and conditions at Zacatón. Eventually, a friend, fellow cave explorer Dr. Bill Stone suggested to Bowden that, “Mother Nature is trying to tell you something.” Bowden eventually gave up on bottoming out Zacatón and turned his attention to other exploration projects in Papua New Guinea and the “Pozzo del Merro 2007, MS Project” near Rome, Italy.