Tourist dies in New Caledonia during a "Discovery Scuba" dive
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Ayisha
Contributor
Don, just so you know, you are supposed to be correctly weighted FIRST, then add the pony - no adjustment required for the addition or subtraction of the pony. A 19 cf AL pony is only 1 - 1 1/2 lbs negative when full, and the empty buoyancy is only just over 1/10 of a lb positive (and your dive's over anyway) - all negligable. Therefore, whether you wear a pony or not, or hand your slung pony over to someone or not, you do not change your weighting for the pony.
I wear a 19 cf pony myself, and was surprised to learn it myself.
You can compare the buoyancy characteristics of various makes and sizes of AL and steel tanks here:
Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan
Also, if you are correctly weighted, which is for the END of the dive, with a possibly nearly empty tank, you should be able to control every inch of your ascent, even if you were to stop 1 foot below the surface or dodge boats or jet skies. If you have all kinds of air in your BC at the safety stop, you are overweighted.
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Yeah, I have a Luxfer 19 and I suppose that chart is accurate: -1.37 pounds full to +.12 empty but then add a reg with 1st & 2nd stages, sling, my particular hoses & spg, then you have a few pounds. I adjust my weight for the suit & water dived with my usual kit so I'm only slightly negative with an empty BC at the end of the dive - but with the 3 to 5 pound pony kit and a full tank, I start off well weighted. 
I haven't done a weight check in a long time; probly should. I dive with a skin, 3 mil, 5 mil, or 7 mil, in fresh or salt, with 80 or 100 cf steel or aluminum tanks and I probly need to do a standard weight check. My adipose ration is up from 7 years ago too. :blush:
I haven't done a weight check in a long time; probly should. I dive with a skin, 3 mil, 5 mil, or 7 mil, in fresh or salt, with 80 or 100 cf steel or aluminum tanks and I probly need to do a standard weight check. My adipose ration is up from 7 years ago too. :blush:
Ayisha
Contributor
Those additions to your pony (all expected with a pony) do not become positively buoyant at the end of the dive. In fact, if you were to adjust for making the pony "complete", you would be removing some of your normal weight since the kit would be more negative, not adding weight. You would not remove weight because of the potential for using the pony or handing it off, then making you underweighted. Your correct weighting before the pony is also your correct weighting with the pony. You will be only slightly negative throughout the dive, but more importantly, you will be correctly weighted if it is handed off.
It is necessary to be a little negative at the beginning of the dive with a full tank in order to be correctly weighted at the end of the dive - when weighting is most crucial to buoyancy control and it is easy to spot over- or under-weighting. Both over- or under-weighting can be dangerous, especially for students or new divers.
Yep definitely. My point was that even without yank and drop it's not a big issue to establish positive bouyancy at the surface - you can use a buddy, an SMB or slip out of your rig.
Not panicking is far more important than a custom reflex to drop weights in my opinion.
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I agree Ayisha. I have never handed off the pony, but just in case - I do my weight balancess without it, then sling it and add air to BC. Doesn't take much, but maybe 5# offset. I like to drop fast but my home bud can't and most boat pic buds can't. Anyway, yes I agree - sorry about confusion.
And I do need to do a new weight check. I could be off on my real needs. I almost always dive with the extra 5# pony rig tho so used to being heavy.
For Whale shark snorkeling in August, we just wore skins and inflatable collars. Now that is different if one hasn't done it lately.
And I do need to do a new weight check. I could be off on my real needs. I almost always dive with the extra 5# pony rig tho so used to being heavy.
For Whale shark snorkeling in August, we just wore skins and inflatable collars. Now that is different if one hasn't done it lately.
Hi, Im an instructor in Thailand and my personal opinion of standards being better in developed countries more so than in exotic tropical locations interesting.
I am based at a very successful PADI CDC center and from my experience of diving in other locations around Thailand i have found standards to be very good. I can however only really speak of Thailand.
I believe its completely down to the individual instructor to enforce good practise. We all work off instructor manuals and various other standards and procedure documents and keeping within these standards doesnt neccesarily mean good practise and safe standards in my opinion.
For example this thread started out about an incident involving a DSD programme, and the DSD programme has come under fire for it. PADI (which is all i know really, however is the largest recreational training organisation) provide Standards that must be adhered to when conducting the programme, now the ratio PADI give an instructor for the DSD programme is 4 students per instructor. I find this to be unsafe, when conducting a DSD you are effectively diving for the student and yourself at the same time, ensuring they are comfortable and in no danger. I personally believe that any instructor could not handle 4 students all encountering problems at the same time. Another standard is the maximum depth, the confined water dive is 6m (I apologise, in my diving career I have never worked in imperial), and the subsequent open water dives are to a max depth of 12m. I would certainly not find it safe to get a new student to complete the required skills at 6m in the same way i think its very unsafe to take a new untrained diver down to 12 meters on their second experience in the water.
So the answer to this is add your own standards, as divers we are constantly taught to be conservative, these standards are there to allow people to conduct the courses in any location and scenarios across the world. For example, how many people actually ascend as fast as 18 meters per minute? By PADI thats fine yet most of us add our own conservatism. I do this with conducting DSD's, I personally wont take more than 2 at a time and i will usually keep quite a lot shallower than my maximum.
Now just because an instructor keeps within the standard does not mean he is a safe instructor and ive met many people who have been trained in the UK, US, etc who have had some bad training experiences which may not have broken standards yet is still questionable.
As for the weighting issue, I always overweight myself when I teach or guide inexperienced divers in case i need to provide a weight for a diver or I need to prevent a diver from ascending too fast, I typically wear about 2-3kilos more than the usual 1.6 kilos i normally wear and My BCD has no trouble whatsoever maintaining positive Bouyancy, I also agree that you should be able to ditch weight...
I am based at a very successful PADI CDC center and from my experience of diving in other locations around Thailand i have found standards to be very good. I can however only really speak of Thailand.
I believe its completely down to the individual instructor to enforce good practise. We all work off instructor manuals and various other standards and procedure documents and keeping within these standards doesnt neccesarily mean good practise and safe standards in my opinion.
For example this thread started out about an incident involving a DSD programme, and the DSD programme has come under fire for it. PADI (which is all i know really, however is the largest recreational training organisation) provide Standards that must be adhered to when conducting the programme, now the ratio PADI give an instructor for the DSD programme is 4 students per instructor. I find this to be unsafe, when conducting a DSD you are effectively diving for the student and yourself at the same time, ensuring they are comfortable and in no danger. I personally believe that any instructor could not handle 4 students all encountering problems at the same time. Another standard is the maximum depth, the confined water dive is 6m (I apologise, in my diving career I have never worked in imperial), and the subsequent open water dives are to a max depth of 12m. I would certainly not find it safe to get a new student to complete the required skills at 6m in the same way i think its very unsafe to take a new untrained diver down to 12 meters on their second experience in the water.
So the answer to this is add your own standards, as divers we are constantly taught to be conservative, these standards are there to allow people to conduct the courses in any location and scenarios across the world. For example, how many people actually ascend as fast as 18 meters per minute? By PADI thats fine yet most of us add our own conservatism. I do this with conducting DSD's, I personally wont take more than 2 at a time and i will usually keep quite a lot shallower than my maximum.
Now just because an instructor keeps within the standard does not mean he is a safe instructor and ive met many people who have been trained in the UK, US, etc who have had some bad training experiences which may not have broken standards yet is still questionable.
As for the weighting issue, I always overweight myself when I teach or guide inexperienced divers in case i need to provide a weight for a diver or I need to prevent a diver from ascending too fast, I typically wear about 2-3kilos more than the usual 1.6 kilos i normally wear and My BCD has no trouble whatsoever maintaining positive Bouyancy, I also agree that you should be able to ditch weight...
NudeDiver
Contributor
No WAY would I have let my wife do a DSD with an instructor and 3 other students. No way. ONE other student - MAYBE - MAYBE - if I could follow along behind them trailing back a way - otherwise, no.
I'm glad my sweetie got to do her DSD dives with the instructor all to herself.
I'm glad my sweetie got to do her DSD dives with the instructor all to herself.
ScubaSteve
Wow.....what a DB
Even then there is not a hope in "that firey place" that I would ever allow a loved on to go on a DSD where there was any more than a maximum of two divers per instructor. If one DSD student panics, it is highly likely that the second student will panic because they have not much more that the very basics...for them to see something going wrong will far too easily instil panic in themselves.
There is also not a hope that I would allow that loved one go to 100'.....not a chance.
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While I did have a 100 ft dive on my DSD, I also did have my own operator employee as a personal/private buddy for each of those 3 dives. What qualifications they may have had, who knows? How many actually card their instructors and DMs? We presume they are as presented.
At least with OW classes an Inst has to do the paperwork. Padi, et all have no control over what happens in DSD. Hell, I could take people on DSDs and no one would know the difference until something goes wrong - but that's shutting the gate after the stock is out.
I would be very leery to suggest a DSD outside of the US without a lot of research, but they are usually done as a spur of the moment decision - so generally, I'd say don't do them. Do your DSD with your Local dive shop, in Florida or Catalina Island CA, or get certified before you go.
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