Eon Steel dive computer

[DevonDiver]

First, is an instructor TEC or otherwise, obligated to teach a student how to use any computer that the student shows up with in any course?

No instructor is obligated to do anything. Agencies provide a syllabus, minimum standards and prerequisite qualifications... but the instructor is not beholden to confirm to those minimums.

Of the agency syllabus and instructor manuals I'm familiar with (many), there's no requirement to teach technical divers how to use their computers... any computers. It's not a skill standard.

I'd suggest any reasonable tech instructor might assume that a contentious tech student might make an effort to familiarise themselves with their equipment before embarking on challenging training.

That said, a good tech instructor might show different practical applications for the information that a tech computer supplies, along with deco theory that ensures the student understands certain principles and practices in setting up and operating the computer safely for the dives they'll undertake.

Second, is the same instructor required to let the student use any equipment that the student wants to?

Again, there's no such obligation.

Most agencies provide a minimum kit requirement for technical diving from training. Nonetheless, the instructor is free to interpret this more specifically.

Some agencies (i.e. GUE) provide a very detailed and inflexible specification of equipment.

At technical diving levels, there really is much more emphasis on the individual instructor - their experience and approach. What you're paying for shouldn't be an 'off-the-shelf' course, but rather a more mentored relationship within which the instructor passes on their expertise and experience for conducting more advanced dives.

It's entirely reasonable to assume that many expert tech instructors will have preferences or requirements needed to fulfill their own specific approach to technical diving.

Third, should the instructor ask in advance to see what equipment the student wants to use before accepting them as a student?

Tech training isn't cheap or easy. The student should begin a dialogue with their instructor well in advance of the course. Equipment configuration should be a major consideration in this dialogue.

My approach to this is to send a 25 page equipment configuration PDF to my tech students - advising them on purchasing and selection options. It's saves them time, money and disappointments. I also invariably exchange dozens, if not hundreds, of emails before they attend for class. My teaching begins long before class starts.

Personally, I'm not at all hard-line about equipment specifics ... as I understand that people have varying budgets and also varying needs in their diving. However, my 'rule' in training is that if equipment causes a safety issue then it's replaced immediately.

I'll advise in advance, but it's the student's decision on what they use for training. If it causes them to fail a dive, then they'll have to rectify the issue and repeat that dive. That applies equally to skills problems as equipment problems.

Equipment can cause issues through failure... or just through being unsuitable to the task.

Faux-tech computers can easily cause failed dives.

 

[KenGordon]

And where will that 'common deco schedule' come from?

Planning software. Say you have one diver with Suunto and one with a Buhlmann computer. You plan the dive twice, once with DM5 and once with MultiDeco. One of the plans with be shorter than the other. Write the longer plan(s) on everyone's slates as the 'plan'. You know it covers the gas requirements and is more conservative than anything any computer on the dive will generate.

Now do the dive. Stick with the stops generated by the most conservative computer.

When doing a dive with a GF computer you are not going to get the same ascent profile as the planning software gave. This is because computer has to assume the first stop for GF low purposes will be at the deepest ceiling when it will never really be that.

This, and the usual computer vs square plan stuff, means you are already not diving a planned profile. So hanging on for the more conservative computer isn't much of an issue.

 

[DevonDiver]

Planning software. Say you have one diver with Suunto and one with a Buhlmann computer. You plan the dive twice, once with DM5 and once with MultiDeco. One of the plans with be shorter than the other. Write the longer plan(s) on everyone's slates as the 'plan'. You know it covers the gas requirements and is more conservative than anything any computer on the dive will generate.

Now do the dive. Stick with the stops generated by the most conservative computer.

When doing a dive with a GF computer you are not going to get the same ascent profile as the planning software gave. This is because computer has to assume the first stop for GF low purposes will be at the deepest ceiling when it will never really be that.

This, and the usual computer vs square plan stuff, means you are already not diving a planned profile. So hanging on for the more conservative computer isn't much of an issue.

So basically, a diver/s may be forced into an ascent schedule that they aren't necessarily comfortable with? Especially with regards to deep stops?

And, in-water, the team may need to spend unanticipated time at a greater depth, and this could penalize other computers with longer shallow deco... for which they might not be equipped with sufficient gas... thus forcing gas reserves to be used... not for an actual emergency... but because of one individual, with one computer, running one specific algorithm....

Conservatism... in bubble model world... doesn't simply mean longer... it means deeper.

So... this: "One of the plans with be shorter than the other. Another will be deeper. Write the deeper stops plan(s) on everyone's slates as the 'plan'. You know it won't cover the gas requirements because other computer models will add further shallower time to compensate for the unanticipated deeper stops in-water and is more conservative than anything any computer on the dive will generate."

What you'd have to do, in practice, is AMALGAMATE the plans.... assuming, of course, that your Buhlman plan was tweaked to include the deeper stops and thus enables off-gassing of the slower tissues it will calculate as being unideally loaded on the deeper RGBM stops,,,

 

[100days-a-year]

Can of worms.Different divers at different depths or the same depth incurring different deco obligations is just plain unnecessary not to mention potentially unsafe in OOA or any other possible emergency. I dive solo mostly but when I dive deep I want buddies who aren't kooks,spastic or overly conservative. I call it a deco obligation or penalty for a reason.

 

[KenGordon]

So... this: "One of the plans with be shorter than the other. Another will be deeper. Write the deeper stops plan(s) on everyone's slates as the 'plan'. You know it won't cover the gas requirements because other computer models will add further shallower time to compensate for the unanticipated deeper stops in-water and is more conservative than anything any computer on the dive will generate."

Below are some example plans, with and without the addition of matching deep stops to delay the GF one to that of the Suunto Fused plan. You will see that they are reasonable approximations of each other. There is a surfacing penalty as you describe, but it is within a few minutes of the basic Suunto plan. So if you plan enough gas for the Suunto plan you will be good.The deep stops would not be unanticipated because the divers would actually plan the dives, spot the difference and accommodate it. Of course if they just jump in the water they will come by surprise, but then so would all the other stops.

There is friction between the two plans of course, but not much more than the differences between two individual divers profiles.

Suunto Fused P-2

Depth Dive time Stop time Mix END pO2 Info
60 m 3 22 TX 18/35 36 m 1.3 Deco
36 m 28 1 TX 18/35 20 m 0.8
33 m 29 1 TX 18/35 18 m 0.8
30 m 30 2 TX 18/35 16 m 0.7
27 m 32 2 TX 18/35 14 m 0.7
24 m 34 2 TX 18/35 12 m 0.6
21 m 36 1 Nx 50 21 m 1.6 Mix change
21 m 38 0 Nx 50 21 m 1.6
18 m 38 2 Nx 50 18 m 1.4
15 m 40 2 Nx 50 15 m 1.3
12 m 43 4 Nx 50 12 m 1.1
9 m 47 1 Nx 80 9 m 1.5 Mix change
9 m 48 3 Nx 80 9 m 1.5
6 m 52 21 Nx 80 6 m 1.3
0 m 73 0 Nx 80 0 m 0.8 Total dive time

P0

Depth Dive time Stop time Mix END pO2 Info
60 m 3 22 TX 18/35 36 m 1.3 Deco
39 m 27 0 TX 18/35 22 m 0.9
36 m 28 1 TX 18/35 20 m 0.8
33 m 29 2 TX 18/35 18 m 0.8
30 m 31 2 TX 18/35 16 m 0.7
27 m 33 2 TX 18/35 14 m 0.7
24 m 36 3 TX 18/35 12 m 0.6
21 m 39 1 Nx 50 21 m 1.6 Mix change
21 m 40 1 Nx 50 21 m 1.6
18 m 41 2 Nx 50 18 m 1.4
15 m 43 3 Nx 50 15 m 1.3
12 m 46 4 Nx 50 12 m 1.1
9 m 51 1 Nx 80 9 m 1.5 Mix change
9 m 52 4 Nx 80 9 m 1.5
6 m 56 25 Nx 80 6 m 1.3
0 m 82 0 Nx 80 0 m 0.8 Total dive time

GF plan, without extra matching

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0m
Conservatism = GF 50/85

Dec to 60m (3) Trimix 18/35 20m/min descent.
Level 60m 22:00 (25) Trimix 18/35 1.25 ppO2, 32m ead, 35m end
Asc to 27m (28) Trimix 18/35 -10m/min ascent.
Stop at 27m 0:42 (29) Trimix 18/35 0.66 ppO2, 12m ead, 14m end
Stop at 24m 1:00 (30) Trimix 18/35 0.61 ppO2, 10m ead, 12m end
Stop at 21m 2:00 (32) Nitrox 50 1.54 ppO2, 10m ead
Stop at 18m 2:00 (34) Nitrox 50 1.39 ppO2, 8m ead
Stop at 15m 2:00 (36) Nitrox 50 1.24 ppO2, 6m ead
Stop at 12m 4:00 (40) Nitrox 50 1.10 ppO2, 4m ead
Stop at 9m 5:00 (45) Nitrox 80 1.51 ppO2, 0m ead
Stop at 6m 23:00 (68) Nitrox 80 1.28 ppO2, 0m ead
Surface (69) Nitrox 80 -6m/min ascent.


GF plan with extra deep stops to match the P-2 Suunto plan
DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0m
Conservatism = GF 50/85

Dec to 60m (3) Trimix 18/35 20m/min descent.
Level 60m 22:00 (25) Trimix 18/35 1.25 ppO2, 32m ead, 35m end
Asc to 36m (27) Trimix 18/35 -10m/min ascent.
Level 36m 1:00 (28) Trimix 18/35 0.82 ppO2, 17m ead, 20m end
Asc to 33m (28) Trimix 18/35 -10m/min ascent.
Level 33m 1:00 (29) Trimix 18/35 0.77 ppO2, 16m ead, 18m end
Asc to 30m (30) Trimix 18/35 -10m/min ascent.
Level 30m 2:00 (32) Trimix 18/35 0.72 ppO2, 14m ead, 16m end
Asc to 27m (32) Trimix 18/35 -10m/min ascent.
Level 27m 2:00 (34) Trimix 18/35 0.66 ppO2, 12m ead, 14m end
Asc to 24m (34) Trimix 18/35 -10m/min ascent.
Level 24m 2:00 (36) Trimix 18/35 0.61 ppO2, 10m ead, 12m end
Asc to 21m (36) Trimix 18/35 -10m/min ascent.
Stop at 21m 0:06 (37) Nitrox 50 1.54 ppO2, 10m ead
Stop at 18m 2:00 (39) Nitrox 50 1.39 ppO2, 8m ead
Stop at 15m 3:00 (42) Nitrox 50 1.24 ppO2, 6m ead
Stop at 12m 4:00 (46) Nitrox 50 1.10 ppO2, 4m ead
Stop at 9m 6:00 (52) Nitrox 80 1.51 ppO2, 0m ead
Stop at 6m 26:00 (78) Nitrox 80 1.28 ppO2, 0m ead
Surface (79) Nitrox 80 -6m/min ascent.



GF plan with extra deep stops to match the P0 Suunto plan
DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0m
Conservatism = GF 50/85

Dec to 60m (3) Trimix 18/35 20m/min descent.
Level 60m 22:00 (25) Trimix 18/35 1.25 ppO2, 32m ead, 35m end
Asc to 36m (27) Trimix 18/35 -10m/min ascent.
Level 36m 1:00 (28) Trimix 18/35 0.82 ppO2, 17m ead, 20m end
Asc to 33m (28) Trimix 18/35 -10m/min ascent.
Level 33m 2:00 (30) Trimix 18/35 0.77 ppO2, 16m ead, 18m end
Asc to 30m (31) Trimix 18/35 -10m/min ascent.
Level 30m 2:00 (33) Trimix 18/35 0.72 ppO2, 14m ead, 16m end
Asc to 27m (33) Trimix 18/35 -10m/min ascent.
Level 27m 2:00 (35) Trimix 18/35 0.66 ppO2, 12m ead, 14m end
Asc to 24m (35) Trimix 18/35 -10m/min ascent.
Level 24m 3:00 (38) Trimix 18/35 0.61 ppO2, 10m ead, 12m end
Asc to 21m (38) Trimix 18/35 -10m/min ascent.
Asc to 18m (39) Nitrox 50 -10m/min ascent.
Stop at 18m 1:48 (41) Nitrox 50 1.39 ppO2, 8m ead
Stop at 15m 2:00 (43) Nitrox 50 1.24 ppO2, 6m ead
Stop at 12m 5:00 (48) Nitrox 50 1.10 ppO2, 4m ead
Stop at 9m 6:00 (54) Nitrox 80 1.51 ppO2, 0m ead
Stop at 6m 27:00 (81) Nitrox 80 1.28 ppO2, 0m ead
Surface (82) Nitrox 80 -6m/min ascent.

 

[KevinNM]

So when you dive again 2 hours later, how similar are they? The typical Suunto pattern I seen is that you start seeing interesting behavior on the second and subsequent dive.

This is particularly true if you moved you arm fast and set off the ascent rate alarms a few times, which then changes the entire dive profile.

 

[DevonDiver]

... if you moved you arm fast and set off the ascent rate alarms a few times, which then changes the entire dive profile.

.... and bang goes all your pre-dive deco and gas planning.

I don't consider this acceptable for technical diving.

 

[Patoux01]

This is particularly true if you moved you arm fast and set off the ascent rate alarms a few times, which then changes the entire dive profile.

Which is something I never managed to do, even when trying. So imagine how much that happens when you don't try

 

[Germie]

First, a trimixcomputer is never obligatory on trimixcourses. It is recommended by some agencies. I did my full trimixcourse with just 2 bottomtimers. I have done 4 dives over 100m/330ft depth with just 2 bottomtimers. Now I have trimixcomputers too.
When I teach a trimixstudent, I do a dive with them in shallow water. If I don't think the student is ok for the course I will say that, and maybe I can give some advice about equipment. What computer I don't care as I want students to train runtimes too. So I let them practise runtimes and if they have a computer they need to do gasswitches too.
Students have some freedom on my favorite 40/80. Last weekend I had one who said, I prefer to be more conservative in the shallow part, can we plan with 40/70? We have discussed that and I said, no problem. Funny detail: we planned with Multideco a dive to 45m with 1 decogas and the computer had only 1 minute difference of our runtimetable. Most times the computer needs less deco than we have planned
In courses I explain the difference between bubblemodels (VPM/RGBM), and Buhlmann, and I show them in Multideco what happens if they plan with vpm, buhlmann+different gf and buhlmann 100/100. Then we discuss pragmatic deco.
DM I had on my desktop before it crashed, but it was not what I prefer. I prefer Multideco. Multideco is widely used and I have done a lot of decodives with it, and you can plan long cavedives with it too.

Next week I have a student who has the Eon Steel (others dive shearwater and Heinrich Weihkamp). We will dive with runtimetables, but I said I am curious what will happen with that computer on depths up to 70m. So please use it as a trimixcomputer. But we will follow our plans and not the computer. So to be continued.

 

[Miyaru]

Interim update: the Suunto Steel from the post above went into error mode for the next 48 hours.
Cause: choosing the new gas at 21m didn't work.
Positive aspect: we were treated to a new-age style of music during the rest of our deco time.

And now for something completely different......someone has a 2nd hand Suunto Aeon Steel for sale pretty soon. This one has a concert option for boring decostops (undocumented feature). I'm pretty sure he is willing to take your SW in exchange, if you wanna upgrade to Steel.