So, I'm planning for a 78m dive with up to 25 mins bottom time. (I.e. actually planning to do it, not theoretically.)

Standard procedures for this bottom time would call for 1 min stops from 57m (with gas switch to 21/35 at 57m), and 2 min stops from 39m.

In light of the many discussions around the web on the latest thinking on the benefits/wisdom of deep stops, I'm wondering if those 1 minute stops - totalling 6 minutes - spent between 57 and 42m are the best approach. Using Buhlmann theory to analyse the inferred profile shows that the gradient factors actually experienced during those 1 min stops are ridiculously low; they also add to the total deco time (greatly in case of loss of the 21/35 deco gas) and add to minimum gas requirements, for little benefit as it appears.

However, using 1 minute stops between 39 and 24m would mean arriving at 21m for the gas switch at around GFHi 85, which seems a little aggressive for that point in the ascent. (And even more aggressive in case of loss of the 57 bottle.)

So I'm proposing 0.5 mins (or, 6m/min) and 2 mins (or, 1.5m/min) as deep stops, with depth ranges as usual. Has anyone else done something like this? And have any comments?

(Incidentally and for clarity, since this is the internet; I'm perfectly capable and willing to decide on my own whether this is a reasonable thing to do , nor am I looking for reassurance - but I'm still interested in discussion and other opinions I've also done the 1 & 2 minute deep stop profile in the past with no issues so it's not that I think the existing procedure is broken, just a way of responding to latest thinking without going overboard, and with retaining the benefits of a ratio approach to deco.)

The analysed plan then looks like:

Phase Depth - Time RunTime Mix O2/He GFHi

----- ------------ ------- --------- --

Descent To: 78m - 5.2 min 5:13 15/55 Ceil:3 / GF:-11

Bottom Phase: 78m - 19.8 min 25:0 15/55 Ceil:28 / GF:-35

Ascent To: 57m - 2.3 min 27:20 15/55 Ceil:29 / GF:-11

Deep Stops 1: 57m - 0.5 min 27:50 21/35 Ceil:28 / GF:3

Deep Stops 1: 54m - 0.5 min 28:20 21/35 Ceil:27 / GF:5

Deep Stops 1: 51m - 0.5 min 28:50 21/35 Ceil:27 / GF:7

Deep Stops 1: 48m - 0.5 min 29:20 21/35 Ceil:26 / GF:11

Deep Stops 1: 45m - 0.5 min 29:50 21/35 Ceil:26 / GF:16

Deep Stops 1: 42m - 0.5 min 30:20 21/35 Ceil:25 / GF:21

Deep Stops 2: 39m - 2 min 32:20 21/35 Ceil:23 / GF:28

Deep Stops 2: 36m - 2 min 34:20 21/35 Ceil:21 / GF:27

Deep Stops 2: 33m - 2 min 36:20 21/35 Ceil:20 / GF:28

Deep Stops 2: 30m - 2 min 38:20 21/35 Ceil:18 / GF:30

Deep Stops 2: 27m - 2 min 40:20 21/35 Ceil:17 / GF:38

Deep Stops 2: 24m - 2 min 42:20 21/35 Ceil:16 / GF:46

Intermediate Stop: 21m - 6 min 48:20 50/0 Ceil:12 / GF:57

Intermediate Stop: 18m - 6 min 54:20 50/0 Ceil:10 / GF:39

Intermediate Stop: 15m - 6 min 60:20 50/0 Ceil:8 / GF:34

Intermediate Stop: 12m - 6 min 66:20 50/0 Ceil:6 / GF:38

Intermediate Stop: 9m - 6 min 72:20 50/0 Ceil:5 / GF:53

6m Stop: 6m - 33 min 105:20 100/0 Ceil:0 / GF:75

Final Ascent: 5m - 1 min 106:20 100/0 Ceil:0 / GF:0

Final Ascent: 4m - 1 min 107:20 100/0 Ceil:0 / GF:15

Final Ascent: 3m - 1 min 108:20 100/0 Ceil:0 / GF:30

Final Ascent: 2m - 1 min 109:20 100/0 Ceil:0 / GF:47

Final Ascent: 1m - 1 min 110:20 100/0 Ceil:0 / GF:65

Surface: 110:20 100/0 Ceil:0 / GF:84

Plan for 78m for 25 mins on 15/55 with 21/35 + 50% + O2

Total Deco: 63 mins - as 6+6+6+6+6+33

Deep Stops: 0.5 / 2

Estimated Total Runtime (including switches and gas breaks): 127 mins