Gentlemen, perhaps a more fruitful investment of your energies would be the academic and training development chairs of the various certifying bodies that still teach the use of deco slate + BT as an acceptable method (in conjunction with another method to track depth and time). Wouldn’t it be a nobler endeavor to convince them to update their curriculum to the standard you’re espousing rather than chipping away at stray individuals on the internet?
For TDI, those people are S
ean.Harrison@tdisdi.com and
Dennis.Pulley@tdisdi.com .
I concur a second deco computer is useful and ideal but the absence of one and the use of a deco slate + BT in its stead doesn’t make the dive inherently unsafe. If that were the case, then I think DAN and certifying bodies would have already campaigned conclusively to eliminate the inclusion of tables + BTs from their courses. Consistently, I think they would have decisively established a policy that diving with two computers is a mandatory certification requirement rather than a good option (current state).
From page 4 of the Shearwater Perdix owner’s manual, the use of tables is contemplated with the self-evident implication that it is an acceptable backup...
“Never risk your life on only one source of information. Use a second computer or tables.
This computer will fail. It is not whether it will fail but when it will fail. Do not depend on it. Always have a plan on how to handle failures. Automatic systems are no substitute for knowledge and training.
No technology will keep you alive. Knowledge, skill, and practiced procedures are your best defense (Except for not doing the dive, of course).”
While you may zero in on
“Use a second computer...”, the way I read Sherwater’s warning is to not become over-reliant on technology. My method of accomplishing that is by continuing to use a deco slate + BT.
Also, I think there are three important considerations at play that warrant attention but are getting conflated.
- Safety
- Affordability
- Facility in planning
Safety - already addressed above.
Affordability - At the beginning of the thread (and still), I approached things from a perspective of “Where do I want to spend my money?” I am blessed with the abundance and will be for the rest of my life to easily afford things like a second Shearwater and not have to look for used ones. I probably should have not used the word “need” when I wrote, “When I need to make a decision between....”. Regardless, I was trained that one deco computer and a deco slate + BT is a safe practice so I’m simply choosing to spend my money elsewhere. I have a raft of observations of fellow professionals who could easily afford upgrades in life but didn’t because what they had was acceptable and safe and they chose to spend money elsewhere. For me, it’s a matter of priorities and focus rather than a shortage of money.
Facility in planning - Shearwater wins but it’s not really drastically slower to run through V-Planner and then transcribe the main dive plan and contingency plans to my slate. The planning speed advantage of a deco computer isn’t significant enough to compel a purchase. I like spending the moment to absorb the data, too.
I’m willing to listen to good arguments and I like evolving my position on matters when it’s warranted but thus far the arguments aren’t outweighing vetted course materials that explicitly state a deco slate + BT is an acceptable method to track a deco dive.