Confused: Suunto D4 Safety Stops

[DevonDiver]

I know a not major local agency who teach computer diving for 10 years during the OW course because majority of the divers use them instead of tables. So they have to know tables AND computers too even if they are only beginners. This agency don't ask money for an extra course...

PADI have done the 'Multi-level (and computer)' spec for a long while, but it doesn't contain any practical knowledge for computer use. The Dive Nav speciality hits the spot, but I can't help thinking that this training should really be given at entry-level, especially as PADI now allow a computer-only OW course.

The majority of the diving community use dive computers as their major (solitary?) dive planning and management aid, but I would hazard a guess that only a tiny percentage of those users really understand what their computer is doing, or have any practical experience handling (emergency) decompression on them. The OP's post illustrates a level of understanding that I've seen all too commonly with divers (up to DM and even instructor level).

I knew a trainee DM once who rushed out of the water "because their computer was malfunctioning". You can guess what the "malfunction" was... it involved the word ceiling and wasn't understood. Luckily that DM didn't get bent either... got lucky.

 

[ElChe]

I knew a trainee DM once who rushed out of the water "because their computer was malfunctioning". You can guess what the "malfunction" was... it involved the word ceiling and wasn't understood. Luckily that DM didn't get bent either... got lucky.

I wonder what "M" means in his DM certification. Surely not Master.

 

[DiveMaven]

In an ironic twist, what saved you from getting bent was the large safety margin of the Suunto. If you violate the more liberal Oceanic DSAT you more likely would get bent.

I would love to see any sort of evidence that divers who use Suunto computers have less incidence of DCS.

It is also very likely that the Oceanic computer in this case never went into deco, only the Suunto did because of it's very conservative algorithym.

 

[DevonDiver]

It was a 'she'. To be fair, there was no point in her formal training where she would have learned about how her computer handled deco situations (other than the computer's manual).

 

[Hawkwood]

+1 Further education would be beneficial. I've seen a few divers omit deco because they've not understood what their computer was telling them in that situation. It's a major over-sight (and something that should be addressed in dive training, now that the agencies are getting more computer-focused)...

Devon,

We teach with computers exclusively. I for one do do explain to my students what that little "hour glass" symbol is indicating and why it got there. Same for the loading bars and ascent rate bars.

Bill

 

[ElChe]

I think the manufacturers know many of the recreational divers older and more overweighted than 30 years ago so even the liberal algorhythm is well within the decompression limits. In the past they dived deeper on air and ascended much faster and they didn't get bends more often than modern divers. But for me is just enough the Suunto no dec time, never had any problem with its limits. Usually I like to spend more time in the shallow where I don't have to think about air consumption and decompression. However I was in the same group with a diver who didn't get into deco but in the night he was in the recompression chamber. In my opinion for most of us the more conservative is the safer but some people use to say I'm too conservative as a diver so maybe it's only my approach.

 

[DiveNav]

......but I can't help thinking that this training should really be given at entry-level, especially as PADI now allow a computer-only OW course.......

I completely agree with you on this.
But unfortunately, in general, the "channel" (Agencies, Dive Stores, Instructors .... but more specifically Dive Stores) don't seem too interested in really teaching model-specific dive computers during OW courses.

I hade several calls with Dive Stores from all over the world about this subject and below are some of the typical responses I get.
a) the dive computer(s) we use in OW are not the ones we would like to sell to our students, so why should we invest time and money to teach them?
b) your online classes go too much in depth .... it take 2 hours to complete your class and our students don't have 2 extra hours
c) we have too many different models of dive computers that we use in OW
d) teaching tables is the only way to teach scuba diving .... and by the way our students don't buy too many dive computers from us
e) we teach already model-specific dive computers in our OW classes; we show your videos in our classroom (the 3 free YouTube videos that give a basic overview of the model-specific dive computer)

 

[ajduplessis]

45min @ 70ft on any DC will give you deco, not just a Suunto (assuming a square profile)

 

[Juardis]

Is that an older D4? I have a new D6i and in my manual it clearly shows the "stop" alert when the computer is telling you to make a RECOMMENDED or a MANDATORY safety stop. My manual indicates the only time I would get a "asc time" alert is when I go into a decompression dive (i.e., I stay down too deep for too long), so as others have said, you went into a decompression dive. However, you should also have seen the "stop" alert, which should disappear only after you make your safety stop. So I don't know why yours didn't. Can anybody answer that question? Other than maybe older versions of the D4 do not have this feature?

The ER will appear if you exceed the ceiling and you have 3 minutes to get back below the ceiling to complete your safety stop. Since you did not complete your safety stop, the computer went into permanent ER (i.e., 48 hours of ER display).

 

[Juardis]

45min @ 70ft on any DC will give you deco, not just a Suunto (assuming a square profile)

On my D6i, per the NoDeco Planning mode for a fresh dive using AO, PO settings (the least conservative), I can only dive 36 minutes at 70ft (square profile) before going into decompression dive.