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May 21, 2007
NASA robot Zacaton sinkhole metrics... or footage?
The El Zacaton (or Xacatun) sinkhole near the coast of northeastern Mexico may well be the world's deepest sinkhole. It's where Sheck Exley lost his life in 1994. His partner Jim Bowden returned from around 900 feet. Neither had found the bottom, which had been plumbed at about 1080 feet.
Now comes interesting news. None other than NASA is using a robot named DEPTHX (which stands for Deep Phreatic Thermal Explorer) to explore El Zacaton, map the vast sinkhole and collect samples. The robot uses sonar for mapping and has an arm to grab things and bring them back to the surface. So far so good.
The whole project seems to be under the auspices of NASA's Ames Research Center, and the project is described in a March 12 article entitled "DEPTHX Robot Prepares to Explore Earths Deepest Sinkhole" on NASA's website at http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=10603. That is where it gets a bit dicey. The second paragraph of the article reads:
Zacaton is a forbidding place. It has never been fully explored, and no one knows exactly how deep it is, but estimates are that its floor lies more than 1,000 meters (well over half a mile) below the surface. A pair of SCUBA divers attempted to plumb its depths in 1994. After descending to 925 meters, one of the divers, Jim Bowden, was forced to turn back. At 925 feet, the water pressure is more than 90 times what it is at sea level. Bowdens partner, Scheck Exley, drowned in his attempt to reach the bottom.
Well. Yes, a forbidding place is certainly is, no doubt there. But that is where the accuracy ends. Does no one know how deep it is? Jim Bowden, Sheck Exley and Ann Kristovich did figure that out when they used a plumb line in April of 1993 and found a depth of over 300 meters. 329 meter or 1,080 feet, to be exact. That is over 1,000 feet, but the article on the NASA site then confuses that with 1,000 meters, which is indeed over half a mile, but also a good three times more than Zacaton actually is. Jim Bowden got down to 925 feet, not meters as stated in the article (Bowden'd be in every record book had he been to 925 METERS, and rather dead). In the next sentence it's correct: feet. But now the author claims the water pressure at 925 feet is more than 90 times that on the surface. He'd have failed PADI Open Water with that answer. Assuming Zacaton is sweetwater, the pressure at 925 feet would be more like 27 times that on the surface. And hey, Exley was not exactly unknown. Let's get his name right. It's Sheck, not Scheck.
Whew. What do we make of this? And of everyone else who simply copied the errors? Just the usual worldwide confusion over the imperial versus the metric system? Why did so many newspapers, websites, and magazines mindlessly reproduce the mistakes? Reuters goes: "El Zacaton, near the Gulf coast of northeastern Mexico, is about 100 metres (328 feet) wide and more than 1,000 metres (3,280 feet) deep. It could easily hold the Eiffel Tower" (http://www.reuters.com/article/scienceNews/idUSN1742917220070518), Six hours later, after someone must have brought it to their attention, a "corrected" version is issued, but it remains wrong: "El Zacaton, near the Gulf coast of northeastern Mexico, is about 100 metres (328 feet) wide and more than 1,000 metres (3,280 feet) deep. It could easily hold the Eiffel Tower." (http://uk.news.yahoo.com/rtrs/20070518/tsc-uk-space-jupiter-corrected-a337f0f.html). Obviously they thought they had the meters to feet conversion wrong when, in fact, they had simply copied the original error.
The Eiffel Tower should have been a dead giveaway; it is about 320 meters, and that would indeed neatly fit into Zacaton...
Most of the world's news media, including news.com, continued to have it wrong, and as of May 21, 2007, the NASA site still has it wrong also. A May 21 article by Ceci Connolly of the Washington Post has it right, and the guys at dailytech.com also caught the error, though they link to a source that includes the error.
Now I can't blame anyone in the news media for taking Reuter's word or NASA's, though a bit of fact checking never hurts. But on the NASA site itself, I really don't like to see this sort of error. I mean, in rocket science, the difference between feet and meters is pretty dramatic.
Note: Much to NASA's credit, a representative from the agency returned my email within hours, confirming the errors, and informing me that the article had been revised. The information is now correct.
Posted by conradb212 at 11:13 PM
May 14, 2007
Pegasus Thruster -- Innovations in SCUBA gear
A big part of my career as a writer, editor and reviewer I have pursued for the past 15 years or so is evaluating new products, figuring out how they fit in, and what their chances for success are. Some are compelling enough to get enthusiastic about, others are incremental improvements, and quite often I found myself shaking my head and wondering, "What were they thinking?!" I must admit that every time I don my scuba gear the "What were they thinking?!" crosses my mind as I fight with some of that unwieldy, heavy equipment. True, it becomes a lot less unwieldy once in the water, but still, it's hard to believe that the current tangle of hoses and snaps and clasps is optimal, that certain aspects of the technology employed is leading instead of trailing edge, and that we aren't in store for some very significant improvement that are not only safer and more convenient, but also make us look less like a Borg out of Star Trek -- a fictitional race of ghoulish cyborgs -- and more like the sleek, stylish divers Cousteau envisioned with his initial scuba gear.
As a result, I am also intrigued to see innovation in scuba gear. I'd love to get my hands on one of those Oceanics masks that have a heads-up display showing all vital dive computer data right in front of your eyes. I was appalled at the four air hoses floating around me in my standard scuba class gear and thrilled when I found I could eliminate one by using a wireless air-integrated dive computer and another by combining the secondary air supply and the BC air hose into a single hose feeding both my BC and my Scubapro AIR2 secondary. Yes, I like innovation, and especially innovation that reduces clutter and simplifies things.
This brings me to a device I came across as I perused the annual Miami Herald Business Plan Challenge. It's the Pegasus Thruster, a novel approach to an underwater propulsion device. Underwater propulsion devices are used to cover distance quickly without exerting oneself needlessly and using up precious air. That comes in handy in cave penetration, and it can also be great fun just scooting around. Problem is that those underwater scooters are quite large. Most are barrel-type devices reminiscent of a shop-vac. They have handles and you hold onto them with both hands. Not exactly optimal when you need a hand for something else, like photography or shooting video. Well, three guys in Florida created a different kind of underwater scooter, the Pegasus Thruster.
Their idea was creating something that is light, handy, and hands-free. There were also practical considerations, like being able to operate the scooter in a variety of ways and replacing its battery while underwater. 
So Dean Vitale and his partners Steve Williams and Howard Sorkin came up with a sleek, elegant unit that is mounted on the back of the diver, on the air tank. The whole thing weighs just 12 pounds, roughly a third to a quarter of a scuba tank. Under water it adds maybe five pounds of negative buoyancy --- easily compensated for via an extra air bladder if so desired. The initial model just has an on/off switch that can be operated by hand, or even by the movement of your head. The little unit is supposed to propel the diver forward at a speed of three knots, which translates into about 3.5 miles per hour. That's more than a good current, and a bit faster than one normally walks on land. Not bad at all. The battery is said to last for a good hour and can be released via a locking pin. Oh, and should the propeller, already protected by wiremesh, become entangled, a safety clutch will keep it from becoming damaged. And you can take it down to 400 feet. And since it is back-mounded, there's never the danger that it kicks up silt. The picture to the left combines screen snaps from the presentation and from the Pegasus Thruster website's video. Click on it for a larger version.
A very cool idea, for sure, and a simple look at the device confirms its sleekness. A patent has been submitted, of course, #20060243188. It claims A scuba diving propulsion system comprising a propulsion apparatus comprising (a) a bracket; (b) apparatus securing said propulsion apparatus to said tank; (c) a battery mounted on said housing; (d) a motive power module mounted on said housing, and including an electric motor, a transmission operatively associated with said motor to increase the torque produced by said motor, a propeller shaft operatively associated with said transmission, and a propeller mounted on said propeller shaft.
There are some very smart details, like a torque increasing transmission, a mounting bracket system that adapts to a tank, and a general design that provides slight downward thrust so that the diver never accidentally shoots toward the surface. There are other details, like provisions to mount the device onto double tanks, or to mount two devices onto a single tank. There are safety measures like automatic cut-off should the unit overheat. And splitting the design into completely sealed modules doesn't only make sense from an underwater battery replacement point of view. It also makes sense as different parts of such a propulsion system generate and absorb different gasses. There isn't any indication as to type and technology of battery power, or how, exactly, it would be replaced underwater. Or how it handles and how you make it go this way or that since you don't hold it in your hands like a conventional scooter.
The trio submitted the Pegasus Thruster to the Miami Herald's Business Plan Challenge. 135 entries were received, 13 were chosen as finalists. The competition was lofty. These were not high school science projects. A plan to screen for adverse drug reactions, one of the leading causes of healthcare disasters, took first place. The Pegasus Thruster came in second. Wow. The Miami Herald wrote a story on the surprisingly strong showing. The trio has invested about $200,000 into the invention so far. Prototypes have been tested by marine cinematographers, the International Association of Handicapped Divers, and the Miami-Dade's Police Underwater Recovery Unit. Initial production units should become available later in 2007, for about $2,400. Though the potential market is significant -- from individuals to scuba gear rental places to professional divers -- the planned ramp-up is conservative. Maybe 20 to 50 units a month.
Hey, it's a very cool idea. The group's website has an excellent underwater demonstration video and there is another video of the trio making its business presentation at the Miami Herald. I wish the video would include a demo on how the unit is operated and how the battery is changed underwater, but that will come. One potential concern I'd have is that having an additional device on your back, and especially one with a propeller and wiremesh, may present a danger of getting caught or entangled, so a quick release is a must in my book. Else, I want one!
Posted by conradb212 at 11:12 PM
May 8, 2007
Pool session
Sometimes the desire to dive just becomes overwhelming. Then it's really good to have a pool in your backyard where you at least can go under. I know, I know. It's laughable. Putting on your scuba gear just to get wet in an eight or nine foot deep pool hardly qualifies as diving, but I find it helpful nonetheless. It's certainly better than having to wait another seven weeks, or whatever, to the next dive trip. And at least to me, getting your dive gear together, putting it on, and experiencing being underwater is educational and good practice no matter when and where. Even if it is just a backyard pool.
So that's what I did last Sunday. It was a warm and sunny California day, maybe 85 degrees and the water in the pool was up to 73 or so. The pool water was clear and inviting (after the total nightmare with runoff from the hills behind my house that had left the pool a murky pond!) and just beckoned me to go in. My 11-year-old son shared the feeling and was eager to don his snorkeling gear.
Getting all my stuff together reminded me just how equipment-intense diving is. I try to keep my gear all together in a special dive bag, but even so, I had to search for my 4- and 5-pound weights, the dive computer turned up in my office where I had last uploaded its data into a notebook computer, and my dive light was missing. Not that I needed it, and I have a good idea where it is, but it was not in the dive bag. So much for keeping everything together.
My two big steel-95 compressed air tanks are in my garage, and one was still full. I knew which one was without hooking up a pressure gauge because I had paid attention in class: full cylinders have their plastic cap on, used one have it off. Carrying the steel tank up the stairs into my house and to the back painfully reminded me just how heavy and unwieldy those tanks are. One of them weighs 44 pounds. That's about as much as a wheel from a modern car, including tire. Picking one of those up and carrying it around is no fun, and few attempt it.
So finally I have everything by the pool, and run smack into the first problem. The belt that secures the tank to my Scubapro Knighthawk BC has a patented snap that needs to be adjusted for a particular tank size. They were set for the smallish 65 cu-ft cylinder I had used in Florida, and that, of course, did not fit the steel-95. Adjusting it is not obvious and the way I did it seemed to pull the velcro when I closed the snap. So I may have done it wrong.
Next problem: As usual, I have to think through how the yoke of the regulator goes onto the tank valve. And, also as usual, I wonder why aren't things designed so they only go on the proper way? As is, I can never remember if the longer part of the first stage points up or down, and so I need to make sure the hose with the regulator is on the right, the wireless transmitter that communicates with my UWATEC dive computer is on the left, and the two hoses screwed into the first stage both point slightly forward, and not backward. There.
Now it's on to the wetsuit. I didn't really need to wear it in the 70+ water for a short dive, but felt the experience wouldn't hurt. Well, guess again. Putting that very tight-fitting 7mm thing on was as big a pain as always. By the time I was done, the sides of my fingernails had dug into into the soft part of my fingertips from having to grab and pull the thick neoprene, I was sweating like a pig, and felt like sausage meat stuffed into a casing. Putting on a wetsuit is no fun. Ever.
Then I sat down and put on my dive socks that I first thought looked a bit silly, but make the dive boots go on and (and later off) much easier and also keep your feet nice and warm. I located the mask defogger, applied it and dunked the mask to wash it off. Put on my dive computer and also the funky Timex Helios Depth dive watch, just to see how it would work. Opened the tank valve, pushed the purge button on the second stage to see if I had air, checked the wireless connection between the transmitter and the computer, saw that I had just 2140 psi of air pressure in what I thought was a full 2640 psi tank (always give your dive shop time to fill the bottles so they can let them cool down, which I hadn't).
I put on the BC and am somewhat pleased that all the hooks and belts and snaps and connectors no longer seem quite as intimidating.
Then came the ever-fun task of putting on my TwinJet fins. No matter how many times I put them on, it still does not come naturally and I find myself fighting for balance until the fins are on and secured. Oh, forgot to put the snorkel onto my Frameless mask. Why they call the clip "quick-release" is not quite clear as it is anything but.
My son had been studying all this with the kind of attention you're likely to get from an 11-year-old. At times he seemed to hang on my every word of explanation, at times every bird in the background seemed more important. However, when I later quizzed him on buoyancy concepts, he had all the right answers, so apparently a kid can watch birds and listen to scuba lectures at the same time.
I make him go through a buddy check and find that I had not put the weight bags into the two pouches of the Knighthawk's integrated weight system. So we do that, I feel another 12 pounds heavier, and now it's time to go down. So I grab the scondary air supply, in my case the Knighthawk's AIR2, hold it up above my head, and push the rectangular button. I remember which of the two this way: the round button adds air to the BC, it's "round-up" or "roundup" and always reminds me what to push when I want to go up. It's hokey, but it works for me. I don't have far to go as my pool is only eight feet deep, but its FUN!!! I thoroughly enjoy breathing air through the regulator, feel the weightlessness and the serenity of the water, even in a pool.
I had brought another piece of equipment, a waterproof Pentax Optio W30 digital camera. It's a neat, sleek 7.1 megapixel camera that doesn't need a special case. Its depth-rating is ten feet and you can keep it down there for two hours. That's not as much as the 33 feet rating of the Olympus 770 SW I had tested in depths up to 70 feet in Florida, but more than good enough for snorkeling and even shallow water diving. The Optio is super-simple. It has an underwater still mode and an underwater movie mode. Once in either of those modes, you still have access to other functions, like white balance or exposure compensation or even different ways of autofocus operation. I am taking pictures of my son snorkeling and looking down, and he takes some of me diving. Later I do some movies that come out exceptionally well. It's amazing that simple 640 x 480 pixel movies from an inexpensive digital camera display great even on a 55-inch projection TV!
The night before I had tried to put my DiveOptx lenses back into my Scubapro Frameless so I could better see the readouts of my dive computer. The soft plastic lenses are supposed to be reusable. But even though I followed all instructions, I could not get them to stick. Also, it's nearly impossible to find a good place for the semi-circular plastic lenses in a modern low-volume mask. By a good place I mean one where the lenses do not obscure your vision while looking ahead and they are in the line of sight for both eyes when you look down at the computer on your wrist. I did find one, but the lenses would not stick there (not that they stuck anywhere else) due to very slightly raised lettering along the inside bottom of the mask glass. Ever since Captain Rudy from Bird's Underwater had suggested I get some "Liquid Glass" at Home Depot and glue the lenses on I had been searching for the glue. In vain. There's liquid steel, liquid wood, liquid everything, but not liquid glass. A Google search revealed that "Liquid Glass" is actually a family of car care products, so Rudy may have gotten the name wrong. I could use superglue, but I am afraid of ruining both my mask and the lenses.
It's a very bright day and so I have no problem seeing the dive computer display or even the smaller one of the Timex. The Timex officially starts a dive once it hits five feet and then it keeps track of depth and dive time, and even surface interval. Its depth reading is totally on the mark and in sync with the UWATEC. Later I found that the Timex had actually also stored depth, duration and "surface interval" of the 23 times I got above and below the 5-foot mark in the shallow pool.
While my scuba lectures had a hard time keeping my son's attention, he's totally fascinated with the bubbles that float to the surface. He follows my bubbles around and lets them pop against his mask. He does that for almost the entire 20 or 30 minute dive. We're having fun!
The chlorine in the pool does its usual thing. Though it is not excessive, my eyes burn and get red, and my nose gets stuffed up. So after showing my son how to properly purge his snorkel after a dive, I step out of my gear, hose it all off, and lay things out to dry and stow others away.
One final problem: apparently I tightened the regulator yoke knob too much as it won't budge. I am too pooped to worry about it. But the next morning I still can't get it open, even with one of those rubber sheets you use to open frozen bottle caps and jar lids. I am about ready to take a wrench to it when it occurs to me to push the purge button of the second stage. Pffffft! I thought I'd done that after I closed the tank valve, but apparently I'd opened it again. Now the yoke knob easily opens. I'd be red-faced if that happened on a dive trip. For now, I commit it to memory. Things to remember when diving, #67.
Posted by conradb212 at 11:12 PM
