VR3 VPM and HE RGBM: do they get along under pressure?

jradomski

I covered both issues, Gap and the explorer are designed for repetitive dives and have built in conservatism to start with when used as recommended (in fact Gap's default SI is 60 minutes), In both cases you are generating tables for both dives (based on SI) not 1 table to be used twice (that as my prev post stated will not work).. How deep a person does repets to is their own personal choice.. For longer dives, the allowable oxygen exposure is more likely to determine how long you have to sit out (and max run time) not decompression limits..

90 minutes is traditionally a good starting point (minimum) for the reasons Joel stated (gives you back half your oxygen exposure).. Its not pushing the envelope its the norm as a starting point, and if you need more allowable oxygen exposure or less deco you extend it as necessary based on needs of the second dive...

If I told someone to run a single table for both dives (which I did not), that would be a problem. I suggested the 2nd has to be planned and taking into account all the limits is part of planning..


Now If you are using the printed published tables, they are consideraqbly more agressive (and depending on the eqpt used, o2 exposures can be quite high) and require longer SI as I have stated.. In fact the tables as published are too agressive for my taste, and I wount dive them..


the "3 hour rule" is part of of the protocols necesssary for using the general RGBM tables since they don't suppor variable SI.. Here are the full rules for those tables

Purchaser/user also recognizes and accepts the following Table protocols:
1) -- descent rate is 60 fsw/min, and ascent rate is 30 fsw/min;
2) -- indicated mix switches are followed on ascent;
3) -- only 2 repetitive decompression dives per day are allowed;
4) -- minimum surface interval (SI) between two dives is 3 hours,
and second dive must be 30 fsw shallower than first dive;
5) -- time-to-fly is 18 hours after a single decompression dive,
and time-to-fly is 24 hours after two decompression dives;
6) -- allowable mix percentage is +/- 0.02 in these Tables;
7) -- decompression sickness and oxtox (full body and CNS) are of
concern to the diver using these Tables;
8) -- ad hoc and user invented add on procedures for these Tables are
neither sanctioned nor tested within these Tables;
9) -- users need be aware of both decompression requirements and oxtox
limitations on all schedules. By common convention, cumulative CNS
clocks stay below 1, full body OTUs clocks stay below 650 on single
dives, and 300 on repetitive dives (2 max in these Tables);
10) -- users assume all risk in using these Tables.

__________________
Joe Radomski
CCR Trimix Instructor Trainer
ANDI Instructor Trainer Director #10

All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.