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At 12:22 AM -0500 12/17/99, William Smithers wrote: >Sean, I missed most of this thread, as I'm not currently subscribed >to this list, but somebody forwarded me your note, and I thought >it worth a public reply. > >The TP2000 (and later TP3000 and TP2750 series) was not a joke. >Well, sortof it was, but you'd have to have lots of closed circuit >rebreather experience to really get it, and the series was proven on some >moderately extreme dives. > >The thing about it was, it was a joke-within-a-joke-within-a-joke, >which, if you look at it with a rebreather designer's eye, wasn't >a joke at all - it was perfectly serious. In fact, I would offer that >it will stand for the next hundred years as the ultimate elegantly >pragmatic, minimalist CCR solution. THAT was the joke. >I can't tell from your post, but it looks like you probably missed >that, as I expect you would, not having any rebreather experience. > >Regards, > >-Will Sean - the "joke" you missed here is that ALL RB's require some kind of moisture absorber - mostly to collect the condensation that results from the temperature differential between a divers exhaled breath (warm) and the ambient temperature of the water (often cold). It is one of the fundamental design issues facing RB designers, and each one has come up with a different way of dealing with that problem. Will's solution was as simple as it was inelegant: Put a roll of TP at the bottom of the loop. Not only is TP incredibly absorbent (except for the kind you find at airports), but it is cheap, and the hole in the middle of the roll is just the right size for gas to flow through uninhibited. And if you wanted that minty-fresh feeling, you could always use the scented Charmin... The rest of the system was rather sophisticated, with solenoid-addition of O2 (TP-3000), adjustable Set-Point, and a nifty little display. Bottom line here, Sean, is that the science of underwater breathing systems is pretty well documented - there are systems out there that work, and some that have not - and the ones that DO work have done so for many years. There are varieties of the ones that do work, and they should be viewed as "mission specific". A couple of years back, Geo and the WKPP boys expressed some rather strong opinions about electronic CCR's - it seemed to a lot of us "E-CCR" boys as bashing, but Geo then explained exactly why they wouldn't work for the WKPP and their explorations, which were (if I can paraphrase): 1) The exploration team had enough to deal with just powering their scooters, marking cave, laying line, and doing surveys without the additional task loading of watching a Primary Display and/or a Secondary. 2) In order to maintain complete redundancy, they needed to have at all times the option to switching to OC gas to get out of the cave systems, therefore they needed to essentially carry enough OC gas for egress, which would really negate the benefits of a Closed Circuit system. 3) The WKPP philosophy was to simplify, simplify, then simplify some more - an electronically controlled rebreather seemed to be a quantum leap of added complexity. When viewed in that light, their avoidance of electronic CCR's made a lot of sense to me, for the environment they were working in. So, Robert came up with the Halcyon, the WKPP used them in their big dive, and the rest, as they say, is history. However, for the kind of work I do, an electronically controlled CCR is perfect. Not only does it provide me with up to 8 hours of dive time on my back, but it is completely silent, which allows us to get closer to the marine life we film. The reasoning behind the "TP" series concept is quite compelling when you think about it - even for a caver or wrecker: IF everything goes wrong, and all else fails, the fact that you could have a very small package strapped to your belt that you can unfurl and breathe out of for up to 2 hours can't be dismissed completely out of hand. How many cave divers who are dead today would be alive if they had this silly little bag strapped on as part of their kit? How many dead wreckers who got silted out, or lost their line would be alive today? Yes - you can make the argument that better planning, better training, better buddies would have saved them too - and that is a very worthwhile goal that we should all try to see accomplished. But if everyone put on their seat belt, we wouldn't need airbags, would we? Of course, Will developed the "TP" series for himself, me, and a few of our buddies who may want something like this. I've got as much experience with CCR building and repair as anyone in the world, damn near, and I can assure you that this system will work. If you were stuck in a cave, like those two dudes who recently died in Madison, and you had one of these babies tucked away, you'd be kissing Will's ass in Macy's window while the parade rolled by... In closing, I'd just like to point out what you yourself said - you've got NO experience with rebreathers. I run into too many dudes who have formed opinions about something, of which they know absolutely nothing. This isn't a flame, just a fact. Each specific model of rebreather out there has strengths and weaknesses. The bashing we RB divers do against each others machines is generally healthy dialog about those positive and negative points. But what it all comes down to is the strength/knowledge of the individual diver. As I have said before, there are guys out there who could do amazing dives using a garden hose and a Sears air compressor, and there are guys out there who could kill themselves using the best equipment on the planet. There is a place for all kinds of diving equipment in the world today - even the lowly TP series... Kevin. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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