Posted by TDI_2 on May 10, 2002 at 09:41:48:
Karl Shreeves recently published an excellent [in my opinion] article entitled Technical Diving Equipment Configuration Based on Objective Data and Theory.
I will first present his conclusions, ver batim, and then I will discuss my own observations about them.
"Conclusion. While various camps within tech/cave diving have historically advocated the gear rigging extremes of complete personal choice to only-our-way-is-right, objective data coupled with theory support a middle position. Theory and data support some standardization, but not in all aspects of gear configuration.
Supported.
1. Community consensus supports that simplified equipment is not the priority. Safety and performance are the priorities.
2. Theory and trials support standardization where inter-team response times are important, such as air sharing and gas shut down assistance.
3. Data support keeping the isolator valve all the way open.
4. Data support the need for rigid hip D-rings when using stage/deco cylinders.
5. Data support the need for adjustable shoulder D-rings.
6. Data support that redundant (double bladder) BCD use does not cause performance issues, provided the backup LPI is secured behind the bladder along the cylinder.
7. Data support a requirement to wear stage/deco cylinders consistently, for standardized cylinder markings, and for following a consistent gas switch procedure.
Not Supported.
1. The data do not support the plate harness over the fabric harness.
2. The data do not support buckle-less harnesses over adjustable shoulder quick release buckles.
3. The data do not support a requirement for only one D-ring per shoulder.
4. The data do not show a meaningful performance difference caused by drag between bungeed and unbungeed BCDs in divers swimming while wearing tech gear. Drag while scootering was not evaluated.
5. The data do not support a standard for the location of stage/deco cylinders."
My own observations:
I believe in complete personal choice for myself. I let others dive rigged the way they want to. Even when I see a clear failure point in their rigging, I can live with that, since its their gear and their life, and not mine. I expect other divers to defer to my own choices for myself as well.
I agree with Mr. Shreeves, that some middle road is probably the best route. Tank marking is probably the area that is most critical for uniformity for a pair or team of divers going down to a wreck. The most likely thing to kill you while tech diving seems to me, from what I have read and learned, to be breathing the wrong gas at the wrong depth. Uniform legible tank markings is the best way to prevent that.
I cant speak for cave diving. I am not a cave diver.
Gear performance is certainly my own highest priority. Thats why I buy and use only ScubaPro. And from among the various ScubaPro product lines, I buy and use only the most sophisticated ScubaPro products. I am lucky enough to have an expert equipment man who has been servicing ScubaPro parts for a long time.
In addition, you just cant beat free parts for a lifetime warranty. I have heard from my friends that Apix from the U.K. has come along and is as good and maybe better than ScubaPro. But I will stay married to ScubaPro.
My TDI instructor and I dont agree on everything. But we do agree that keeping the isolator valve turned opeo ONLY A MINIMUM amount makes it faster to shut down, and thats how we both keep it. I guess we disagree with Mr. Shreeves here.
My TDI instructor completely agrees with Mr. Shreeves on securing the backup LPI of the double-bladder B/C out of the way. This prevents confusion when you are being assisted by someone else underwater. I myself disagree with both of them, and I keep my backup LPI mounted on my right front, where I can get to it fastest when and if I need it. I am not worried about someone else trying to assist me and making a mistake, because nobody else touches my gear, ever, as a rule.
My TDI instructor and I both prefer the "rich to right / lean to left" system for stage/deco cylinders. I have found that I can mount the left one a little higher and the right one a little lower, and then I have complete access to reach all points on my gear and body in the middle, as well as good trim while swimming or hanging in deco.
I have found the fabric harness to be sufficient for all my own tech applications. I get good horizontal trim even though I dont have a backplate because the benefits of perfect weighting allow me to use the bubble in my drysuit to keep me horizontal. With a minimal bubble inside the suit, you have greater control over your trim and horizontal position. However, for my next B/C I may very well go to a backplate model, since that seems to augment horizontal trim even more.
I really like my adjustable shoulder straps and quick release buckles. Im glad Mr. Shreeves has given this more credibility with his research.
I have never tried bungeed wings. I probably never will. Those have been shamed so much that I dont want to call attention to my gear by having them. And since it seems possible that scootering could be a problem with bungeed wings, thats all the more reason to me not to buy or use bungeed wings. The worlds record deep tech dive was made with OMS bungeed wings, however, in their defense.
The thing I enjoy the most from TDI training is that it allows me the most personal freedom of choice in rigging my own gear. I have heard that the other training agencies are more rigid. That is why I will continue to stick with TDI, for myself.
I welcome alternative views and comments. Thats how we all learn from each other.
Finally, thank you, Mr. Shreeves, for your research and its publication. This will give us a lot to talk about at our next TDI meeting at our dive club.
/s/ TDI Diver #100,001