Place of dive tables in modern diving

[dmaziuk]

• Suunto Dive Planner 1.0.0.3 (supposedly using Suunto RGBM)

The rumour is that Suunto "technical" RGBM running in Eon Steel and Dive Planner is not the same as Suunto "recreational" RGBM running inside Zoops and Vypers. The latter is detuned, presumably to lower the risks over 6-7 days of diving.

 

[Storker]

But that is exactly the issue, plus what would happen with a fast ascent, or a yo-yo dive, or using a GF less than 100/100 (which I believe no one does and is in no computers that I know of).

ISTM that if I'm violating established standards for safe diving (doing fast ascents, doing yo-yo dives, skipping safety stops or jumping back in as soon as I've switched my empty tank for a full one) perhaps some extra conservatism might be in order.

And considering that the average rec scuba diver is middle-aged and not exactly an Olympic athlete, perhaps it's a good idea to back off a bit from those NDLs anyway. Particularly if those NDLs are given by the most liberal algorithms on the market. As an aside, I find it rather interesting that if I analyze my own modest dives with e.g. ZH-L16 50/80, I've been under a ceiling on quite a few of my dives. Even when I weren't riding my NDLs

Anyway, my simple exercise clearly shows that the blanket statement that Suuntos are so much more conservative than other computers (or algorithms) is just wrong. Yes, they may impose a penalty if you're violating long-established standards for safe diving, but they aren't generally more conservative than other 'puters/algorithms. If you want to convince me otherwise, show me the hard data that support your blanket statement.

 

[scubadada]

The rumour is that Suunto "technical" RGBM running in Eon Steel and Dive Planner is not the same as Suunto "recreational" RGBM running inside Zoops and Vypers. The latter is detuned, presumably to lower the risks over 6-7 days of diving.

There are 3 versions of the Suunto algorithm, RGBM, Technical RGBM, and Fused RGBM. The DX, Eon Core, and Eon Steel run the Fused RGBM Suunto RGBM Dive Algorithms there is an additional link for a much more detailed explanation for the Fused RGBM. It has been discussed previously on SB that computers running Fused RGBM and be adjusted to be quite liberal. @Diving Dubai has considerable experience with an Eon Steel.

 

[jlcnuke]

ISTM that if I'm violating established standards for safe diving (doing fast ascents, doing yo-yo dives, skipping safety stops or jumping back in as soon as I've switched my empty tank for a full one) perhaps some extra conservatism might be in order.

And considering that the average rec scuba diver is middle-aged and not exactly an Olympic athlete, perhaps it's a good idea to back off a bit from those NDLs anyway. Particularly if those NDLs are given by the most liberal algorithms on the market. As an aside, I find it rather interesting that if I analyze my own modest dives with e.g. ZH-L16 50/80, I've been under a ceiling on quite a few of my dives. Even when I weren't riding my NDLs

Anyway, my simple exercise clearly shows that the blanket statement that Suuntos are so much more conservative than other computers (or algorithms) is just wrong. Yes, they may impose a penalty if you're violating long-established standards for safe diving, but they aren't generally more conservative than other 'puters/algorithms. If you want to convince me otherwise, show me the hard data that support your blanket statement.

https://c-7npsfqifvt34x24betx2ecpoo...ftu-Tfqufncfs-3125-ebub.qeg_$/$/$/$?i10c.ua=1

This is the objective test (Scubalab did) which was done by putting the computers in a chamber and pressurizing it to simulate depth changes and depressurize it simulating multiple dives (using actual computers experiencing actual pressure changes). By the 4th dive, Suunto's computer (using the Suunto RGBM algo) had the second shortest dive time remaining (Cressi's Leonardo being the worst in that scenario). The dive time remaining for the Suunto was only 2/3rds that of the average computer (actually less since the Liquivision Lynx was on "you're not going to go into deco" mode by then but I just left it off when computing the average), and less than half of the most liberal dive computer (the Aeris A300 CS).

In fact, on every dive the Suunto computer comes in with below average no-deco times allowed relative to the other computers tested. To me, that seems to clearly support stating that Suuntos are more conservative than other computers, and in some situations MUCH more conservative than other computers.

 

[tursiops]

Yes, they may impose a penalty if you're violating long-established standards for safe diving, but they aren't generally more conservative than other 'puters/algorithms.

I would not call a 45min SI a violation of a "long-established standard for safe diving" but I can't argue with your statement that Suuntos are not generally (do you mean "always"?) more conservative.....but it does seem they may be needlessly more conservative in certain situations....which tend to be those situations common to recreational divers, like shorter SIs, faster (but not unsafe) ascents, and up-and-down but not square profiles.

 

[Storker]

it does seem they may be needlessly more conservative in certain situations....which tend to be those situations common to some, but far from all recreational divers, like shorter SIs, faster (but not necessarily unsafe) ascents, and up-and-down but not square profiles.

I can agree on this.

 

[tursiops]

I can agree on this.

Cool! Now where can we publish our jointly-authored statement?
Wait! We just did! On SB.

 

[Storker]

Now we only need to wait three months for the reviewers' statements. I'm not looking forward to what reviewer #2 has to say.

 

[tursiops]

Now we only need to wait three months for the reviewers' statements. I'm not looking forward to what reviewer #2 has to say.

LOL You too? I've always had a problem with reviewer #2....

 

[Diving Dubai]

@scubadada - Remind me to beat you HARD - for sucking me in to this....

Alrighty - where to start. Suunto RGBM?

So on a computer with Fused, it does just that. Fro shallow it leans towards normal Suunto RGBM, and when you go deeper it moves to Technical RGMB

In practice, the only time I’ve seen it be conservative, is when doing repetitive multi day dives with short (less than 60 mins) SI

Generally I have longer SI - 90mins

If diving an AL 80, and diving to 30m but also wanting a 60m dive, thus balancing depth/Air consumption/time, I’ve never had an issue

If I’m mooching on a scooter, Yo Yoing maybe down to 50m on air with a 32% back gas - its not an issue, sure you get a little deco but not much, and normally I come shallow anyway (15m) at the 30-40min mark to off gas. My computer might show no deco, but if I’m been diving aggresiveily, then I like to add my own conservatism.

Similarly I’ve had a fast ascent (big up current), my buddies Aladdin had a 24hr lock out, not my Eon

Also I’ve put my most aggressive setting against a Perdix most aggressive setting on two back to back dives - the Perdix had marginally less NDL.

All that said, my opinion is this. Get Deco trained. Even if you never go into Deco the added information makes you a more informed diver.

Next, whether you dive tables, RGBM or Buhlmen - always remember that the models only predict. You don’t know how near or far to the M line your body tissues actually are. And neither does the computer.

I’d rather take a couple of mins deco or add my own SS extensions than ride the NDL - but that’s just me.

Do I really give a FF between a computer that gives 22 vs 25 mins of NDL.... Not really