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Billy I said: >The best way IMHO is under the crotch strap, <snip> > >My view is that if they forget to drop a weight belt when using a >conventional BC, then whether it is under or over the crotch strap makes no >difference at all. If we are considering an inexperienced diver who >accidentally loses a weight belt, there is the possibility that in panic they >will hold their breath on the ascent. This act is likely to produce severe >lung damage, whereas any bend would have most likely been curable. You replied: >With respect, I think you're allowing for the wrong >problem. They're not so inexperienced that a breathhold >ascent and embolism is likely. However, loss of primary >bouyancy can happen to anyone - hoses pull out, inflators >fail. Then, the jetissonable wightbelt is the ONLY bouyancy >device. It should not be compromised. And a lot of problems >happen on or near the surface. The only real argument against putting the weight belt under the crotch strap is that if the weight belt has to be dumped by a deliberate act of the diver, then it takes more time to dump. The problem is that with your loss of buoyancy point, you have much more time to sort the problem out than with a gas failure. Therefore, we are OK to take a bit more time to release the crotch strap. WRT to point about incidents happening on the surface, I agree, in this scenario, I would prefer to have my weight belt quickly dropped and therefore over my crotch strap. This is because at this point in the dive the other risks cannot occur. Once underwater, the balance of the other risks mean that I choose to put my weight belt under my crotch strap. I have seen so many cases of people nearly loosing and once or twice actually loosing their weight belt that I consider this to be the real risk, rather than the inability to drop a weight belt. So you have to look at all of the areas where problems can occur, look at the solutions and assess potential risk. It seems we have the same facts and come up with a different conclusion. >In my mind, I'm running through the struggle I'd have to >clear a weightbelt that I've dropped which is then caught >inside my crotch strap and holding me under. It's hanging >between my legs with half the weights on each side. I have >to lift the whole weightbelt up and pull it up and away clear >of the crotch strap, hoping the weights don't catch on the >webbing, or I'm in deeper shit. Or I have to undo the waist >strap of my harness and slide the crotch strap off it - >against the weight of the hanging weight-belt, hoping the loop >doesn't catch on the buckle on the way off. Only then can I >let the weightbelt fall away. And the ONLY reason I dropped >the belt in the first place was because I desperately wanted >to take a fucking breath! (excuse the language, I got a bit >wound up thinking about it). But life can be a bitch sometimes. There's you above with your paranoia. In your nightmare, you've probably messed up to be so low on gas for this to be an issue. We all say, "not me" but humans will be fools sometimes, so I recognise your concern. My concern is that I'm happily monitoring my gas, enjoying my dive and suddenly my weight belt drops off and I go ballistic to the surface. For those still with us, I rarely dive a weight belt but have adjusted the teeth on mine to give a firm snap shut i.e. they should be greater than and angle of 90 degrees to the lever part of the buckle. >I think the idea of using a weightbelt is to be able >to drop it, not to have it trapped on oneself. IF >accidentally dropping the weight belt was the REAL >problem, why not just do away with the quick release. Now, you're being a silly Billy :-) This is why people use V-weights, to avoid the accidental dropping and for the ergonomics of the set up. A weight belt is designed to be ditchable, we are merely discussing the avoidance of one of its failure modes viz. accidental ditching. <snip> >Nope. I don't mean that. The accidentally >dropped weightbelt problem should be prevented >by using a good stainless steel buckle, allowing >an adequate tail of webbing to run through it, and >closing it firmly. Not by using the crotchstrap >to tie the belt to the diver. Agreed, except your last sentence. >These guys are capable of free ascents from 15 - 20, maybe 25 >metres. But 30 metres? 35 metres? I would like to think they >understand the importance of tight team diving. But they're >kids and kids get distracted. Ascent could still be a necessity. "kids get distracted" - if this is something you consider probable then they should not be left unsupervised. >There's nothing hard and fast here. But when these guys start >doing deeper dives, 30-40 metres, where a free ascent to the >surface starts to assume more risk, or when they're doing >dives close to Dr Buhlmann's NDLs, then I think I'll encourage >them to clip a small sling cylinder off on the front as a back >up air source. Of course on the left side. This topic, ponies, has been discussed ad nauseum before and is not related to weight belt ditching so I'll not comment further. >How are the mine dives going? Fine, but you make it sound so un-romantic. I'm back in South Africa after a short week or so overseas and will be at Badgat this weekend. I was planning a "Star Trek" dive but have a slight cough (UK and Italian weather) and have not really had the time to do any planning. Things do not feel right due to this lack of preparation, so I will not be pushing anything. It looks like my assignment in South Africa will be extended for a year but nothing is certain yet. If I get extended, I'll bring out all of my kit including my WKPP scooter. Boy that'll be fun even in a mine!!! David Shimell Project Manager, Sequent Computer Systems Ltd., Sandton, South Africa. Email: shimell@se*.co* <mailto:shimell@se*.co*> -----Original Message----- From: bdi@wh*.ne* [SMTP:bdi@wh*.ne*] Sent: Thursday, May 13, 1999 12:16 PM To: Shimell, David (shimell); cspencer@te*.co*; techdiver@aquanaut.com Subject: RE: Halcyon experience in Australia? At 08:28 AM 12/5/99 -0700, Shimell, David (shimell) wrote: >>So if Jack (the nipper) or his buddies ever need to drop >>the belt during self rescue or helping out someone else, I >>feel happier that it can be done quickly, easily and in a >>single movement. > >The best way IMHO is under the crotch strap, but I understand your points >about a newbie being more easily stressed and making the wrong decisions, >specifically forgetting to drop the weight belt. We see many sad cases of >drowning with newbies who panic and are found on the bottom with weight belt >still attached. > >My view is that if they forget to drop a weight belt when using a >conventional BC, then whether it is under or over the crotch strap makes no >difference at all. If we are considering an inexperienced diver who >accidentally loses a weight belt, there is the possibility that in panic they >will hold their breath on the ascent. This act is likely to produce severe >lung damage, whereas any bend would have most likely been curable. With respect, I think you're allowing for the wrong problem. They're not so inexperienced that a breathhold ascent and embolism is likely. However, loss of primary bouyancy can happen to anyone - hoses pull out, inflators fail. Then, the jetissonable wightbelt is the ONLY bouyancy device. It should not be compromised. And a lot of problems happen on or near the surface. In my mind, I'm running through the struggle I'd have to clear a weightbelt that I've dropped which is then caught inside my crotch strap and holding me under. It's hanging between my legs with half the weights on each side. I have to lift the whole weightbelt up and pull it up and away clear of the crotch strap, hoping the weights don't catch on the webbing, or I'm in deeper shit. Or I have to undo the waist strap of my harness and slide the crotch strap off it - against the weight of the hanging weight-belt, hoping the loop doesn't catch on the buckle on the way off. Only then can I let the weightbelt fall away. And the ONLY reason I dropped the belt in the first place was because I desperately wanted to take a fucking breath! (excuse the language, I got a bit wound up thinking about it). Thus, in >the case of a newbie, the ramifications of accidentally dropping a weight >belt is not of a bend but of lung damage which can occur at the depths to >which a newbie would be diving i.e. it can happen in a swimming pool. As >the diver progresses in experience and depth, lung damage should be less >likely but a bend more likely. An experienced diver should be able to cope >with removing the crotch strap to drop the weight belt but can do nothing >much to deal with a weight belt which has already been dropped by accident. >So avoiding the problem in the first place is the best action, i.e. retain >the weight belt under the crotch strap. I think the idea of using a weightbelt is to be able to drop it, not to have it trapped on oneself. IF accidentally dropping the weight belt was the REAL problem, why not just do away with the quick release. > >>When they start to dive deeper or get into longer exposures, >>still no-deco stuff, but where a quick trip to the surface >>might have consequences, I'll introduce the alternate air >>source. I'm thinking about a 3 litre pony slung from the >>front - sort of early stage-training. What d'you think? > >I read this paragraph several ways, so please excuse me if I am inferring >incorrectly. > >Inference 1: if you are saying that to deal with the case of a dropped >weight belt, you are going to provide an alternative air source, this does >not make sense. Deal with the cause, not the symptom. I'm sure you don't >really mean this. Nope. I don't mean that. The accidentally dropped weightbelt problem should be prevented by using a good stainless steel buckle, allowing an adequate tail of webbing to run through it, and closing it firmly. Not by using the crotchstrap to tie the belt to the diver. > >Inference 2: if you are saying that if some problem occurs, you will provide >an alternate air source to allow the diver to sort the problem, then this is >common sense and what we all do. However, I can't see how this has any >bearing on how a weight belt is carried. In fact, having a alternate air >source furthers the argument of carrying the weight belt under the crotch >strap. It takes longer to drop the weight belt when under the crotch strap. >The alternate air source provides additional time over that available from >the primary air source. These guys are capable of free ascents from 15 - 20, maybe 25 metres. But 30 metres? 35 metres? I would like to think they understand the importance of tight team diving. But they're kids and kids get distracted. Ascent could still be a necessity. There's nothing hard and fast here. But when these guys start doing deeper dives, 30-40 metres, where a free ascent to the surface starts to assume more risk, or when they're doing dives close to Dr Buhlmann's NDLs, then I think I'll encourage them to clip a small sling cylinder off on the front as a back up air source. Of course on the left side. > >Moving on to your possibly-not-so-related issue of carrying a pony, I >presume you mean having it stage mounted on the left. I prefer to think of >ponies as small stage bottles. This is for two reasons: > >1. If you carry one, you rig it the same way as a stage. >2. The gas capacity of the stage must be appropriate to the dive being >undertaken. > >Note that I have not entered the debate on single plus stage vs. Doubles. I >occasionally dive with a 3 litre stage but carry oxygen in it for deco and I >dive doubles. I don't own a 3 litre cylinder so don't dive this arrangement >very often besides, my deco is requires more gas than is available in a 3 >litre stage. However, I don't see how a stage is relevant to your point? It's not. I went and introduced a new topic. How are the mine dives going? rgrds billyw -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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