40M dive 30 mins CCR

[Twinset & Wing]

STUARTS XS

Profile is in minutes for bottom time

0m >> 40m 6min; Air RT: 6min
40m >> 40m 30min; Air RT: 36min

Decompression Plan

24m for 2min Air RT:38min
16m for 2min Air RT:40min
6m for 11min Air RT:51min

Total 11min

M11F6 Algorithm used
Safety Factor:1m

Closed circuit dive
Set point: 1.3
28/12/07

I think that I am still getting used to the lack of deco I have on a ccr or am i missing somthing, DDplan gave me a longer overall runtime by about 5 mins.

I am going to run on HLplanner also.

what are you guys getting with no gradient factors set.

Giles

[scribley]

V-Planner gave me the same runtime as you have roughly with +2 conservatism. (used 39m as PDA version)

[Janos]

Five minutes here or there isn't really anything. Proportionally it might seem like a lot but different alogorithmns will get you to stop deeper and that makes a big difference, as you can't stop for 20 seconds so the computer programme will round it up to the nearest minute.

For 30mins at 40m, I'd do:

1@21m,
1@18m
1@15m
1@12m
3@9m
11@6m

And then some to keep Baby Jesus happy. However that's running 15/55 dil (it's what I have) and 1.2 on the bottom, then 1.4 from 21m, and 1.5 from 6m up. Deco is Bulhman 30/85

Practically it will probably be a bit different as my ppO2 will fluctuate more, and I let it drop on the ascent.

Janos

[NotDeadYet]

If you're diving <50m, especially if you are on air, then M11F6 will not stop you as deep as VPM or GF will. Obviously this will have a knock on effect on the deco time.

I use 18/40 for anything less than 50m, I never use an air dil ever so I'm not overly familiar with how the algorithm behaves in that range.

Cheers,

Stuart

[Twinset & Wing]

thanks guys, and thanks stewart for the insight

[Ahmed Adly]

CCR rocks the house!
On OC with ratio deco, I would have double that deco time.

[Twinset & Wing]

indeed it does, indeed it does

[NotDeadYet]

Originally Posted by Ahmed Adly

CCR rocks the house!
On OC with ratio deco, I would have double that deco time.

Weird, I've actually found the opposite. OK, I never used ratio deco, I generally used software but since I went CCR I've found that my deco times are either equal or longer compared to the OC equivalent.

I dive mCCR and I plan dives usually on 1 or 1.1bar setpoint, partly because any higher and I start getting itchy lungs on long dives (I also don't hike the PO2 up until 6m) and partly because I want to account for my setpoint not always being as constant as it should (ahem ). It's not unusual for the dive plan to be a bit longer than the bailout and there have been a couple of times where I've thought "f*** it" and come off the loop to get out the water quicker (yeah, I know, take a table for a higher PO2, don't you love hindsight). I don't like assuming an ideal world of, say, a constant 1.2 when I'm on mCCR, I've had two proper bends and I don't want a third.

Oh well, maybe it is time to get the shiney new Shearwater that I keep drooling over.

Cheers,

Stuart

[Janos]

Originally Posted by NotDeadYet

Oh well, maybe it is time to get the shiney new Shearwater that I keep drooling over.

That was part of my reasoning for getting the Shearwater. I too like to drop the ppO2 on the ascent, and then boost it at 21m, 12m, and 6m (ish).

Getting rid of the three independent KISS displays was a wrench though.

Janos

[Ahmed Adly]

Originally Posted by NotDeadYet

Weird, I've actually found the opposite. OK, I never used ratio deco, I generally used software but since I went CCR I've found that my deco times are either equal or longer compared to the OC equivalent.

Well on for 30min on 40m I would have a deco profil like this:

40m 30 ' air
30-1
27-1
24-1
21-3 Deco50
18-1
15-1
12-3
9 -4
6 -14

with a comparison like this, the difference would become more obvious for the longer and deeper dives.

All I need to do is sell my last 18 apatments, and I will have the time to go forth and buy the KISS.