Until recently I have always been a BT and Tables diver and always planned my own dive even when diving with a group charter. In fact I have turned down computers on rental equipment dives and thumbed more than one dive when my time was up based on the profile planned and actual dive executed regardless of what the DM or guides computer said the 'groups' NDL was because that was how I planned the dive (side note: I recommend trying this, the look from a new diver after giving the 'instructor finger waggle' to a DM is worth the cost in bottom time alone).
I'm not out to set a bottom time records and enjoy conservatively planned dives even at the loss of bottom time or depth. I'm not looking to enter a discussion about the merits of comp vs. BT; I just dive tame profiles and BT/Table is how I was trained (read: what I am comfortable with).
I finally purchased my first DC (Suunto Zoop). My choice to dive a computer is more one of redundancy than expediency. I will still dive my full SPG console with depth gauge and carry a bottom timer. I will still monitor both in the fashion I always have during a dive along with the added computer check. In reading the Zoop manual the procedure for correcting a computer failure is as follows: Ascend to 60ft, slow ascent to 30ft per minute, hold at 10-20ft for as long as air will allow, surface and discontinue diving for 24hrs minimum.
My question is why? The Zoop's failure outline makes sense if you have no redundancy, no idea what your bottom time is, no idea what you depth is and no plan other than 'trust the comp'. But, if I maintain contingency plan based on where the RDP places my PG, know the elapsed BT and maximum depth, why could I not just transfer the dive back to a BT/Table dive and proceed as planned. Once topside any subsequent dives that day (and probably trip) would be planned off of the RDP. I have to believe the RDP is more conservative than even the most conservative DC algorithm particularly when diving a square max depth profile and not using a eRDPML. Ignore any scenarios where the RDP puts me past an NDL, these are leisure dives that should remain well inside of any deco obligation.
I'll provide two examples:
- Dive 1 of a day. Planned profile is 60ft for 35 minutes. Computer fails 10 minutes in. I don't know exactly when the comp failed but I know I am 10 minutes into a 35 minute dive via my BT. Why do I need to ascend? Why can't I continue the dive based on the planned profile and exit the water in PG 'N' per the RDP; conduct a surface interval and proceed to dive 2?
- Dive 2 of a day (different day not related to example 1). Post SI, RDP says I would be an 'E' if you calculate a square profile using the table. Planned profile is 50ft for 45minutes. Comp fails 40 minutes in, thumb the dive and proceed to boat. Why could I not use the RDP to figure out I am a PG 'T' then proceed as planned later that day to dive using data from log and RDP for both of the previous two dives?
Curious how the SB community views this. I don't need to know that I am doing redundant math if I plan dives in this fashion, I know that and I'm happy to self identify as a math nerd. Besides, the point of redundancy is to be able to safely mitigate any critical equipment failure. Thanks!