What computers are you using for tech dives?

[OkByMe]

Because we know what model Shearwater and LV are using.

Scubapro, suunto, etc all use proprietary algorithms or make proprietary adjustments.

The OP's question was what computers are used for tech dives... Not about tanks and valves, gear rigging and safety procedures. I assume the OP was interested in trying to determine which, if any, computer they might consider to become their own. My question was centered around testing, comparing and validating the suitability of computers for decompression diving. so I say again...
Often wondered why Liquid vision and Shear water is not included in most Decompression studies...http://www.nurkopedia.pl/images/9/92/Sayer_-_Decompression_management_by_43_models.pdf

How does a stated decompression algorithm actually perform under testing and comparison with other computers? What do these companies have to hide? The fact that we are all NOT dead from using these computers as a part in controlling a dive plan... simply means the science can be approached from more than one direction. Simply saying that we know this or that company is using something they claim is the best for the application is not a means to prove it...

 

[rongoodman]

Often wondered why Liquid vision and Shear water is not included in most Decompression studies...http://www.nurkopedia.pl/images/9/92/Sayer_-_Decompression_management_by_43_models.pdf

Well, it's Liquivision and Shearwater. At the beginning of the paper, under Methods, it states that computers in common use in the UK were chosen and only recreational computers are seen on the list.

 

[PfcAJ]

There's not a whole lot of value in testing something you already know the answers to when you're on a limited budget and timetable.

The tested computers all have a lot of ??? built in to their proprietary algorithms that SW and LV just don't have.

 

[scubadada]

The OP's question was what computers are used for tech dives... Not about tanks and valves, gear rigging and safety procedures. I assume the OP was interested in trying to determine which, if any, computer they might consider to become their own. My question was centered around testing, comparing and validating the suitability of computers for decompression diving. so I say again...
Often wondered why Liquid vision and Shear water is not included in most Decompression studies...http://www.nurkopedia.pl/images/9/92/Sayer_-_Decompression_management_by_43_models.pdf

How does a stated decompression algorithm actually perform under testing and comparison with other computers? What do these companies have to hide? The fact that we are all NOT dead from using these computers as a part in controlling a dive plan... simply means the science can be approached from more than one direction. Simply saying that we know this or that company is using something they claim is the best for the application is not a means to prove it...

It appears that the authors of the study chose the computers to undergo testing, "Single examples of 43 models of dive computer that are in common use in the UK (Table 1) were set to default settings and all were in sea water mode." The corresponding author's email address can be found at the end of the article, you could ask him.

 

[DevonDiver]

Often wondered why Liquid vision and Shear water is not included in most Decompression studies...

They're probably not paying (one way or another) to be included.

 

[KenGordon]

Since the other thread is locked due to the usual madness, here are some numbers for various combinations of the Suunto RGBM version, with and without the deep stop feature, Tech (Helo2) vs regular (Zoop, Vyper etc).

These are the NEDU test 170 ft (52m) leaving the bottom at 30 minutes all on air. I have added some GF profiles as well as the Thalmann and BVM(3) (A and B) profiles.

Generally you can skip the deep stops on a Suunto so I have shown both plans. They are counted down in seconds and typically one or two minutes (I have never had one longer than 2 minutes).. The ceiling shown in DM5 for the deep stop enabled profiles is the first stop depth on the equivalent deep stop disabled profile.

As you can see the Suuntos get shallow quickly and do the stops shallow. Differences are obviously exaggerated by decoing out on air.

D - Depth (m), A - arrival at that depth, L - leave that depth, T stop time. Some rounding etc omitted and the NEDU ones don't really add up.


Suunto Tech RGBM P-2 no deep stops:

D A L T
52 3 30 27
9 34 40 6
6 40 58 18
3 59 106 47

Suunto Tech RGBM P-2 with deep stops:

D A L T
52 3 30 27
31 32 33 1
20 34 36 2
14 37 39 2
9 39 42 3
6 43 63 20
3 63 117 54
0 118

Suunto RGBM P0 no deep stops: (eg Zoop)

D A L T
52 3 30 27
18 34 35 1
15 35 38 3
12 38 46 8
9 47 56 9
6 57 86 29
3 86 177 91

Suunto RGBM P0 deep stops:

D A L T
52 3 30 27
35 32 33 1
26 34 35 1
15 36 39 3
12 40 49 9
9 49 60 11
6 60 89 29
3 89 185 96

Suunto Tech RGBM P0 no deep stops:

D A L T
52 3 30 27
12 34 36 2
9 36 45 9
6 46 70 24
3 70 155 85

Suunto Tech RGBM P0 with deep stops:

D A L T
52 3 30 27
32 32 33 1
21 34 36 2
15 37 39 2
9 39 47 8
6 48 73 25
3 74 166 92

GF 30/70:

D A L T
52 3 30 27
27 32 33 .5
24 33 35 2
21 35 38 3
18 38 42 4
15 42 48 6
12 48 57 9
9 57 73 16
6 73 102 29
3 102 159 57

GF 45/85:

D A L T
52 3 30 27
24 32 33 .2
21 33 35 2
18 35 38 3
15 38 42 4
12 42 49 7
9 49 60 11
6 60 80 20
3 80 121 40

GF 90/90:

D A L T
52 3 30 27
15 33 36 3
12 36 41 5
9 41 50 9
6 50 68 18
3 68 102 34
0 103

GF 100/100:

D A L T
52 3 30 27
15 33 35 2
12 35 39 4
9 39 46 7
6 46 62 16
3 62 91 29
0 91

NEDU A (Thalmann)

D A L T
52 3 30 27
12 34 43 9
9 43 63 20
6 63 116 53
3 116 209 93


NEDU B (BVM)

D A L T
52 3 30 27
21 33 45 12
18 45 62 17
15 62 77 15
12 77 95 18
9 95 118 23
6 118 135 17
3 135 207 72

I took the stop times from Table 1. The surfacing time ought to be 204 minutes (30 BT and 174 TTS) it specifies the stop times do not include travel time so I do not know why they don't add up.

 

[Ayisha]

It inserts fake deep stops which can be ignored.

Generally you can skip the deep stops on a Suunto

What would be the point of advocating or using a computer algorithm that produces a profile that you admit that you can "ignore" or "skip"? It doesn't sound like you have much confidence in it. Much like the prevailing opinion.

 

[KenGordon]

What would be the point of advocating or using a computer algorithm that produces a profile that you admit that you can "ignore" or "skip"? It doesn't sound like you have much confidence in it. Much like the prevailing opinion.

The prevailing opinion here is received wisdom.

I can ignore any stop I like on a Shearwater and it will continue to calculate a profile. That is often put forward as an advantage here on SB.

The point is that the deep stops in particular are optional. The actual ceiling is at the depth of the first stop given by the plan with deep stops disabled. If you are of the opinion that deep stops are a mistake you can chose to dive GF 80/80 (or whichever x/x) or disable deep stops on the Suunto models that allow it, ignore them on those that do not. As expected you get to the surface faster that way, both with GF and with the Suuntos.

I have higher confidence in the Suuntos than my random choices of GF numbers. I have seen thousands of dives executed with Suuntos.

 

[OkByMe]

It appears that the authors of the study chose the computers to undergo testing, "Single examples of 43 models of dive computer that are in common use in the UK (Table 1) were set to default settings and all were in sea water mode." The corresponding author's email address can be found at the end of the article, you could ask him.

No... this is what I searched and this is what I found... Nothing said about recreational.

Key words
Computers – diving, occupational diving, decompression, dive profile, decompression tables
Introduction
Dive computers can be accepted in some occupational diving
sectors as tools for managing decompression.
1
However, the
choice of which dive computer could be used for occupational
diving is difficult because the number of models available
is considerable. The choice is further complicated by the
many different decompression algorithms employed in dive
computers, with some being modified by manufacturers in
unspecified ways.
2
In Europe, standards and normatives that
underpin CE marking for dive computers do not stipulate
operational limits for decompression management.
3,

 

[Tom Ahola]

@KenGordon I have, so let's play for sh!ts and giggles. I just downloaded Suunto's DM5 planner thing so let's run some easy profiles

160ft for 30 mins, on 21/35 using EAN50 as sole deoc gas on GF50/80-what I'd dive. Basically same total time as what Jim would have with 30/85 with a dive this short.
70-1
60-1
50-2
40-2
30-5
20-8
10-15
total-35

same dive, but using 30/70 since it came up
80-1
70-1
60-2
50-2
40-3
30-6
20-10
10-18
total deco-44

Suunto Tech as used on the Helo2 with P0 because I don't know what that actually means and it was default. Deep stops turned off
70-1
40-2
30-7
20-9
10-30
total-56mins

please explain how that is "very similar"? I can't actually force buhlmann to get that ascent profile with that long of a deco obligation. The closest I got was 80/60 *yes it was backwards*

Hi! I just jumped here following a link from another thread. I feel I have to comment on this although it is an old post. I did not see anyone else reacting on the ICD in this dive when I quickly browsed other following posts.

Switching from 21/35 to EAN50 gives you an ICD hit. The Bühlmann is a simple algorithm and does not protect the diver from mistakes or suicidal attempts. The RGBM however, being a slightly more accurate model of what happens in the diver's body, reacts in more details to what the diver does. So in this dive the RGBM algorithm tries to protect the diver from being bent or killed by a suicidal counterdiffusion by prolonging the decompression.

The P0 means nominal personal setting. One should set the personal setting to a higher value when diving in cold, when under fatigue, at old age, in bad physical condition, when inexperienced, long time since last dive or with minor medical issues. In good conditions the personal setting can be set more agressive (negative) to shorten the decompression. This is like tweaking the Bühlmann gradient factors according to personal conditions.

- Tom from Suunto