CAPTAIN SINBAD
Contributor
Ok … so after reading all the back and forth exchange on ratio deco, I decided to sign up for UTD Technical-1, do a few dives with Ratio Deco and then come back here to state my opinion about this “dangerous and controversial” practice that is taking so much flak. I will be the test-rat of my own experiments and this blog which I plan on keeping as an open diary for everyone to see, will be updated with my progression as well as my own thoughts as they evolve through the course. As I move into this journey, I also invite the whole scubaboard to come with me on here as if they were doing it.
I am already certified for decompression diving to that depth and I am presently doing those dives using dive computers, desktop software and I also consult conventional tables occasionally. UTD Tech-1 will therefore be more of a linear training experience than an upward one. You may ask what is in it for me? To be honest, I am not sure. It will give me first-hand experience with one of the most (if not the single most) controversial and misunderstood issues in diving.
I take into this class a few concerns of my own which I state below.
If I am still missing any of the criticisms of ratio deco then please let me know so that I may add to the above list. I am making this journey with an open mind and I hope that the readers and participants who follow me here will do the same. Let us be honest with ourselves. Decompression is still a scientific mystery so this is not meant to be a thread where one prophet logs on to burn the other false ones at the stake. There are so many other threads where that is already happening. Instead I am hoping that this will be a thread that every single person will be able to follow and say that they learnt something that they did not know before be is positive or negative.
As this blog progresses, each of the above may generate so much discussion that moderators may have to branch them into their own threads just so that you can follow whatever bothers you the most. Everyone’s opinion is welcome and appreciated. A few whose opinions I would love to hear are:
@Dr Simon Mitchell
@boulderjohn
@Dan_P
@Kevrumbo
@PfcAJ
@TBone
@rjack321
@Doppler (Steve Lewis but I think he dives more and logs less which is why he is so happy.)
Many thanks,
Sinbad.
I am already certified for decompression diving to that depth and I am presently doing those dives using dive computers, desktop software and I also consult conventional tables occasionally. UTD Tech-1 will therefore be more of a linear training experience than an upward one. You may ask what is in it for me? To be honest, I am not sure. It will give me first-hand experience with one of the most (if not the single most) controversial and misunderstood issues in diving.
I take into this class a few concerns of my own which I state below.
- Applying ratios at altitudes: This has been mentioned here a number of times. I believe I even read an article by George Irvine understating the importance of adjusting to altitudes. I had the chance to briefly discuss this with a UTD instructor and she said that she was not trained for altitude diving but she believed that Ratio Deco tables would have to be adjusted for altitudes. Altitude diving is not in Tech-1 but I will still bring it up.
- Depths and Exposure times where ratios fall apart: There has to be some external way of understanding the departure point where following fixed ratios is causing you to deviate from safe-zones that exist between two different algorithms.
- Spisni study and its interpretation by UTD: This showed that the initial assumption that UTD as well as the bubble modellers had about deep stops being more effective than buhlmann ascents was wrong. It was partially acknowledged by UTD and the first stop was increased from 75% depth to 66% depth but the 66% depth is till “deep.” For reference, please see: UTD Decompression profile study results published
- Dropping gradient factors on repetitive diving: If you are doing repetitive diving on consecutive days, then it may make sense to drop gradient factor hi as the days progress and then to allow a full day of recovery before resuming again from the higher gradient factor. How would a ratio deco diver accommodate this?
- The UTD min-deco table is the same for Nitrox 32 as well as 25/25. This is looking to be dangerous on 25/25 because if you have a gas mix that is 25% oxygen and you are applying limits that are calculated for 32% oxygen then that is a 7% more oxygen then what that table is originally meant for. GUE uses 30/30 as their standard gas and they were using it for a table that is for 32% so that is a 2 percent deviation but if you are using a standard mix of 25 and your table is the same as 32 then the difference is significant (IMHO.)
- Mental task loading specially when dives go wrong: I have used RD min deco-table for a few test dives and I did not find the mental depth averaging to be overwhelming. It was simple block mathematics which seemed pretty hard to mess up on. I would love to expand further into this concept on dives with more complicated profiles and also when you have accidentally exceeded the limits of the memorized min-deco table.
If I am still missing any of the criticisms of ratio deco then please let me know so that I may add to the above list. I am making this journey with an open mind and I hope that the readers and participants who follow me here will do the same. Let us be honest with ourselves. Decompression is still a scientific mystery so this is not meant to be a thread where one prophet logs on to burn the other false ones at the stake. There are so many other threads where that is already happening. Instead I am hoping that this will be a thread that every single person will be able to follow and say that they learnt something that they did not know before be is positive or negative.
As this blog progresses, each of the above may generate so much discussion that moderators may have to branch them into their own threads just so that you can follow whatever bothers you the most. Everyone’s opinion is welcome and appreciated. A few whose opinions I would love to hear are:
@Dr Simon Mitchell
@boulderjohn
@Dan_P
@Kevrumbo
@PfcAJ
@TBone
@rjack321
@Doppler (Steve Lewis but I think he dives more and logs less which is why he is so happy.)
Many thanks,
Sinbad.
Last edited: