I had a bcd failure once when a inflator broke at bcd thread area and water filled. I was only shore diving in 10ft and very in shape in mt teens and it was everything to tread water i didnt want to ditch weights so i had plenty of gas and choose to swim in at the bottom but it did open my eyes to how fast accidents can happen.
I did a reasonably scientific test and found a worst case for cylinder buoyancy of 4.6kg difference between 210 and 50 Bar, twin 12 litre Apeks steels, fresh water. At 210 Bar they were a total of 5.9kg negative reducing to 1.3 at 50. That's just the cylinders, marked at 13.7kg weight each. Clearly this depends on your individual tanks but it suggests your change of 7kg from full to empty is on the high side. Otherwise all good stuff. As you say, the first test is whether your rig can float itself with full cylinders and any non-ditchable weights you normally attach to it.
These videos are awesome, and you guys really need to upgrade your microphone setup. It's really easy to make this audio a lot smoother for not a big investment. It would make the videos much for enjoyable.
Don't forget the negative weight of battery of lamp and/or heating. But in yuor calculation is some room, but better to mention those also (in stead of the wetnotes ;-) 🙂 )
Just want to get you correct, do not use steel tanks because if you have to swim up with a bcd failure even ditching weights would be very difficult? You said ocean diving, why not true in all diving? Thanks
#askmark I recently started diving a Full face mask (OTS Guardian), another FFM diver and I discussed the loss of air approximately 400 to 600 psi when using the ambient breathing valve on the surface. He suggested using the Inline Shut-Off for Second Stage to shut the air flow off while using the ambient breathing valve on the surface. Beyond the adding usual failure point , is there other pros and cons you can discuss. Thank You
At 5:57 you're saying that a 12 l tank has "a little bit more" buoyancy than 12 kg. Actually, the difference is quite significant: Assuming that your two steel tanks weigh 28 kg together, and the density of steel is 7.8 kilograms per liter, then the volume of the steel only is about 3.6 liter, giving you 3.6 kg of additional positive buoyancy. Why would you neglect that if on the other hand you care about little details like the buoyancy of your fins?
Where‘s the positive buoyancy of drysuit and undergarment being accounted for? Depending on the undergarment it can be quite significant, even when soaked (e.g BZ400). I agree on a smaller wing being unable to float the equipment when full. But I do not see a use case where I would have to float my equipment in a cave environment. Or did I miss something? Open water is a different story, though.
Welche Kapazität, betr. Wing, braucht man - als kleine Person (Frau mit 155cm Grösse, und AluFlasche/ Standard Flasche, Warm Wasser Tauchen mit ca1- 3 - 5 mm Neopren Anzug, lokal im warmen Wasser bis 24 grad temp, und um auf Reisen zu nutzen. ( nicht Dtl. lebend !) ca. 2-4-5 kg Blei nutzen. mit Alu Backplate. Reicht ein Wing mit 17 lb oder 20 lb / Lift ? Oder braucht man mehr Lift ? mit ca. 27 lb oder 32 lb aber nur fuer ein Tank.
First off, I appreciate your content, so please take these comments as constructive criticism. Please stop saying “obviously”. There is no “obvious”. If there were, no one would watch your content and there would be no other way of diving. Explain why without the bias of supposing that your answers are the only “correct” ones. Those who came up with other solutions to scuba problems presumably thought they were giving good advice for some reason. ISE (GUE or DIR) believes that there is a better solution. Please explain when you think you have a better solution (1) what is the perceived weakness of conventional “wisdom” and (2) why you believe that your solution addresses that weakness. Doing so will help those of us who are thinking critically to evaluate what you are proposing. Second, you state numbers for positive or negative buoyancy. Where did these number some from? How can we derive such numbers for ourselves? Is there a means by which ordinary people can measure the positive and negative buoyancy of themselves and their gear? If so, how does that weighing happen?
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Lucky I saw your video first before I buy my equipment! Thanks for your great sharing!!
I had a bcd failure once when a inflator broke at bcd thread area and water filled. I was only shore diving in 10ft and very in shape in mt teens and it was everything to tread water i didnt want to ditch weights so i had plenty of gas and choose to swim in at the bottom but it did open my eyes to how fast accidents can happen.
Another excellent video, thank you Achim
I did a reasonably scientific test and found a worst case for cylinder buoyancy of 4.6kg difference between 210 and 50 Bar, twin 12 litre Apeks steels, fresh water. At 210 Bar they were a total of 5.9kg negative reducing to 1.3 at 50. That's just the cylinders, marked at 13.7kg weight each. Clearly this depends on your individual tanks but it suggests your change of 7kg from full to empty is on the high side. Otherwise all good stuff. As you say, the first test is whether your rig can float itself with full cylinders and any non-ditchable weights you normally attach to it.
Lot of great points. My 1st stage regulators are heavy
These videos are awesome, and you guys really need to upgrade your microphone setup. It's really easy to make this audio a lot smoother for not a big investment. It would make the videos much for enjoyable.
And then you see many (or most?) technical divers diving 40lbs/18.1Kg Wings for D12+80cuft...
Don't forget the negative weight of battery of lamp and/or heating. But in yuor calculation is some room, but better to mention those also (in stead of the wetnotes ;-) 🙂 )
Great description thank you
Sehr anschaulich erklärt!
Just want to get you correct, do not use steel tanks because if you have to swim up with a bcd failure even ditching weights would be very difficult? You said ocean diving, why not true in all diving? Thanks
👍😎Very interesting! Thanks
Thank you
#askmark I recently started diving a Full face mask (OTS Guardian), another FFM diver and I discussed the loss of air approximately 400 to 600 psi when using the ambient breathing valve on the surface. He suggested using the Inline Shut-Off for Second Stage to shut the air flow off while using the ambient breathing valve on the surface.
Beyond the adding usual failure point , is there other pros and cons you can discuss.
Thank You
I'm interested in your book but is this also available in e-book version? I travel a lot and e-books are my solution to keep reading books.
At 5:57 you're saying that a 12 l tank has "a little bit more" buoyancy than 12 kg. Actually, the difference is quite significant: Assuming that your two steel tanks weigh 28 kg together, and the density of steel is 7.8 kilograms per liter, then the volume of the steel only is about 3.6 liter, giving you 3.6 kg of additional positive buoyancy. Why would you neglect that if on the other hand you care about little details like the buoyancy of your fins?
There are 12 Liter steel tanks in a weight range between 12.0 up to 14.5kg.. So it really depends.
Where‘s the positive buoyancy of drysuit and undergarment being accounted for? Depending on the undergarment it can be quite significant, even when soaked (e.g BZ400). I agree on a smaller wing being unable to float the equipment when full. But I do not see a use case where I would have to float my equipment in a cave environment. Or did I miss something? Open water is a different story, though.
And if the drysuit floods early in the dive?
Welche Kapazität, betr. Wing, braucht man - als kleine Person (Frau mit 155cm Grösse, und AluFlasche/ Standard Flasche, Warm Wasser Tauchen mit ca1- 3 - 5 mm Neopren Anzug, lokal im warmen Wasser bis 24 grad temp, und um auf Reisen zu nutzen. ( nicht Dtl. lebend !) ca. 2-4-5 kg Blei nutzen. mit Alu Backplate. Reicht ein Wing mit 17 lb oder 20 lb / Lift ? Oder braucht man mehr Lift ? mit ca. 27 lb oder 32 lb aber nur fuer ein Tank.
First off, I appreciate your content, so please take these comments as constructive criticism. Please stop saying “obviously”. There is no “obvious”. If there were, no one would watch your content and there would be no other way of diving. Explain why without the bias of supposing that your answers are the only “correct” ones. Those who came up with other solutions to scuba problems presumably thought they were giving good advice for some reason. ISE (GUE or DIR) believes that there is a better solution. Please explain when you think you have a better solution (1) what is the perceived weakness of conventional “wisdom” and (2) why you believe that your solution addresses that weakness. Doing so will help those of us who are thinking critically to evaluate what you are proposing.
Second, you state numbers for positive or negative buoyancy. Where did these number some from? How can we derive such numbers for ourselves? Is there a means by which ordinary people can measure the positive and negative buoyancy of themselves and their gear? If so, how does that weighing happen?