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RE: catastrophic zipper failures on drysuits: >I have, and in only 5 years of diving. What make zipper? All are not equal. Viking uses the NASA spec stuff, there are many unsatisfactory imitations. >And another case where a DUI TLS >sprang enough of a leak in a boot to totally flood the suit in a few >minutes. How can a leak in a boot affect the air bubble in the shoulders? IE: Keep yer boots down and it's not an issue. I'm not a fan of the TLS either, although I have one here someplace as a spare. >I don't doubt the reliability of drysuits in general. But it takes only >one failure of this nature to convince me that betting my life on a >drysuit is stupid. Your choice. I prefer thinking and skill to carrying more crap. My experience is that a NASA spec zipper is as close to 100% reliable -if properly maintained- as a hammer. NASA thinks so too. That's good enough for me. Plus I do have a way out, it's just statisically not worth worrying about how. >A zipper separation, or failure to close the zipper completely, would >certainly render the suit useless for buoyancy control rather quickly. Agreed. As I said. it would also threaten the divers life with catastrophic hypothermia fairly quickly, eh? Why not wear one drysuit inside another? I mean, you can take hypotheticals to an extreme and make redundancy to such a state that you'd need a crane to b lowered into the water. >You probably loose 6 or more pounds of ballast during a dive due to gas >used. That means you've got 6 more liters of gas in the suit at the start >of each dive than at the end. How do you manage that bubble? Dunno. In 25 years of diving with drysuits I have never worried about it or thought it worth contemplating. It's like the difference between goose shit and fly shit. The geese shit in my driveway and it peeves me because I see it. The flies all shit on my driveway too, but it's invisible and I'm not peeved. Just never been an issue. Just curious, not for any sinister reason, but how many drysuit dives to you have? Lots of questions are answered with a few hands-on experiences. Things that loom large to people that have not done it are sometimes considered of little importance to people doing it all the time. As an example, you would think that the loss of an engine on a jet after takeoff with a fire ensuing would scare the crap out of most non-pilots and of most private pilots, but a professional pilot trained twice a year in a simulator considers it an amusing game. Nothing more. >> but I'm not overweighted, and in fact can swim to the surface >> with a completely flooded suit in all of my gear (and have gone to >> the quarry and proven it by having a buddy unzip my suit for trials). >You must be pretty heavy, and that swim would take a tremendous amount of >effort! Not a good thing to do at the end of a long dive with a >significant deco obligation IMO. I have additional -mass- but that does not equate to being heavy insofar as bouyancy is concerned. mean, take off all of yer crap and throw it into a pool. Your bottles may sink or float. Dunno. Depends. Lets say they are neutral for the sake of discussion. Your mask fins and crap is all about neutral. Your drysuit is either negative bit (like mine) or is positive (like a CF-200). Your underwear is hollow fibers, so it floats even when wet. So far the whole system is fairly neutral. Yuu float naked with a full breath. Water in water is nil bouyancy value. Add it all up and it is -all- neutral of maybe a bit positive in the water. Your weightbelt should be neutralizing any bouyancy of suit and underwear, that's all. So flood the system and you are -still- essentially neutral if you were weighted correctly to begin with. You have -mass- added but not -negative bouyancy-. Hmm... how do I say this: You can brace your feet against a passenger liner and push it off from the dock because although the mass is large, the friction is low. Once moving it's not an issue. I've tried it and it works. Is is 'as easy' as doing it dry? No. Can you do it? Sure. Will you ever need to? Probably not. Is it worth thinking about? Sure. Worth worrying about? Not as far as I'm concerned. You may be different in your risk analysis. Be my guest to be different than me. I'm not saying that my way is the only way. Go for it! >Seems workable. But don't you think you're putting yourself at risk having >to work that hard during the deco phase of a dive? Nope. The risk/benefit analysis is in the favor of more streamlined and less gear. I have -a- way to bailout. Actually I have two. No sweat. Feel free to do otherwise yourself, as I said before. >> Remember, in many thousands of witnessed drysuit dives I have never >> seen anything this catastrophic occur. >Here's where we differ. I have seen a failure of this nature, and I call >that significant evidence of the possibility. Be my guest to believe that. I've not seen it. I'd be interested to examine the incident that you describe and determine A: what type of zipper failed, B: how it was maintained, C: If it was damaged during an incorrect sipping (most likely) and D: the mode of failure. If it can be atributed to incorrect use or maintenance, that can be eliminated as a potential failure by mere application of -skill- and proper technique. You might be interested in "Daves 10 rules of Aeronautical Success" which applies to diving too: Proper Prior Preflight Planning & Preparation Prevents Piss Poor Post-takeoff Performance. Take care of yer zipper and it'll take care of you. (That goes for your drysuit zipper too.... ;-) >Why don't you use the BC all the time? What advantage is there in *not* >having it? Less hoses. Less crap. Lower drag. Not worth it in most cases. Used when needed. Left at home when not. Selection of the correct tool for the correct job. Feel free to wear yours all the time. I'm not telling you how to dive and would never do so. Regards, Dave Sutton -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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