Diving with gradient factors for a new recreational diver

[scubadada]

And I'll bet many of those are Suuntos.

I have kept loose track of the computers over 12 years. Most of them have been computers running a version of RGBM, Cressi, Mares and Suunto. A couple of times it has been a computer running PZ+. I have no idea what conservative factors were being run on any of them. The single common thread is that none of them seemed to know that they had gone into deco and had a mandatory stop. In many cases, it seems like the affected diver had been diving with a buddy or group with more liberal computers and simply were staying with them.

 

[boulderjohn]

And I'll bet many of those are Suuntos.

The computer in my story was indeed a Suunto.

 

[boulderjohn]

One of the problems with computers is the RTFM problem. If you read the manual, the whole thing, there is a good chance you will come out of the experience thoroughly baffled. After page after page after page after page after page of stuff you will never need to know, you will realize that the stuff you needed to know was scattered throughout those pages, but you somehow missed them or can't remember them. That was indeed my experience with my first computer, The stuff I really needed to know, which could have been concentrated in two pages, was scattered throughout the manual, without clear headings to help you find them.

I think it is likely that computer manufacturers are afraid to put the critical stuff (nitrox settings,, unintended decompression, etc.) in one, easy-to-find place for fear that in some subsequent lawsuit, someone will argue that putting that stuff there was incentive for the reader to skip the rest. It is better to put everything that could ever possibly be useful in there in such a way that the reader is required to read the whole damned thing in order to find the few items that were actually needed.

Years ago I bought my first tech computer (which I won't name) on eBay. It arrived without a manual, so I looked for one online. I found a PDF version. To my surprise, it was a PDF of a late DRAFT of the manual, with review comments in the margin. Those comments revealed a constant fear of writing something in the manual that could get them sued in case of an accident. Being crystal clear in what you write turns out to be a bad thing.

 

[Dan]

One of the problems with computers is the RTFM problem. If you read the manual, the whole thing, there is a good chance you will come out of the experience thoroughly baffled. After page after page after page after page after page of stuff you will never need to know, you will realize that the stuff you needed to know was scattered throughout those pages, but you somehow missed them or can't remember them. That was indeed my experience with my first computer, The stuff I really needed to know, which could have been concentrated in two pages, was scattered throughout the manual, without clear headings to help you find them.

I think it is likely that computer manufacturers are afraid to put the critical stuff (nitrox settings,, unintended decompression, etc.) in one, easy-to-find place for fear that in some subsequent lawsuit, someone will argue that putting that stuff there was incentive for the reader to skip the rest. It is better to put everything that could ever possibly be useful in there in such a way that the reader is required to read the whole damned thing in order to find the few items that were actually needed.

Years ago I bought my first tech computer (which I won't name) on eBay. It arrived without a manual, so I looked for one online. I found a PDF version. To my surprise, it was a PDF of a late DRAFT of the manual, with review comments in the margin. Those comments revealed a constant fear of writing something in the manual that could get them sued in case of an accident. Being crystal clear in what you write turns out to be a bad thing.

I only have 2 dive computers, SUUNTO D4 and Shearwater Teric. SUUNTO manual is horrible to read. Shearwater Teric manual is so easy to read, it's like night and day in comparison to that of SUUNTO D4.

 

[scubaozy]

I was doing a series of dives working with students in several advanced classes. I would work with one class, then switch to another for the next dive, etc. While I was doing this, the people who were not in classes would dive on their own.

At then end of one of the dives, when we surfaced, one of the divers who was not in the class for that dive surfaced at the same time we did. He announced that his computer had started acting weird on that dive. It said something unusual, and then instead of counting down the NDL, it started counting numbers up. What was up with that? I immediately asked him what number he ended up with, but he had not checked recently and didn't know. I took him down to safety stop depth. Looking at his computer, I saw that it was in error mode. We stayed 15 minutes. I took him up to the surface and had him breathe oxygen for a while to be safe. He was OK.

Yes, you need to know what a computer is doing if you use one. One thing you should know is when it is giving the length of a required deco stop if you violate NDLs.

Years ago we used to think the proper thing to do in OW training was to teach students how to use tables and then send them out into the diving world knowing they will not use those tables and will instead buy a computer, with no instruction on how computers work.

I think problem is in training agencies. @Angelo Farina earlier made a comment about this as well and I think I very much agree with him. Removing decompression categorically from rec diving is in my eyes the culprit of these problems. For instance, a cmas 2* diver will do their training with either Buhlmann or Deko 2000 (Hahn) tables. Whether you do deco diving or not, students see and learn and understand staged decompression as 3-6-9 meter stops are already in the same table. I had no confusion when I first time saw the computer telling me to go to 3 meters.
On the other hand, other commercial agencies, when you exceed ndl, they call it emergency decompression. No wonder rec divers are very scared of "getting into deco".

 

[boulderjohn]

Removing decompression categorically from rec diving is in my eyes the culprit of these problems.

What agency has removed decompression from their training?

 

[MrVegas]

Yep, GF high of 75 is already more conservative than my Suunto Zoop Novo on the first dive.

On my first dive with a Perdix on the default setting (tech mode) my reaction was "wait . . . I had way more no deco time last week." (Compared to my Aqualung i300.) Algorithm comparisons are always interesting. For a first dive, I think the Navy Dive Tables give you a 25 minute NDL at 100 feet and Buhlmann 99/99 gives you something like an NDL of 17 (?) and setting the GF high lower takes it down from there. In theory, all of the algorithms provide some concept of an acceptable level of risk, but there are always gray areas. I think the default on the Perdix is 30/70.

Manuals for recreational computers don't always seem to cover very well what happens when the computer goes into deco, even if you do read them. When your computer starts suddenly flashing "up" it can be confusing if you haven't thought about you're doing before hand.

 

[boulderjohn]

I only have 2 dive computers, SUUNTO D4 and Shearwater Teric. SUUNTO manual is horrible to read. Shearwater Teric manual is so easy to read, it's like night and day in comparison to that of SUUNTO D4.

...and the one I could not make head not tail of a quarter century ago was a Suunto.

Several decades ago we entered the world of personal desktop computers, and a whole bunch of models appeared on the scene, with names you would have to search your memory now to recall. I read an analysis that indicated that the best of those early computers was made by Coleco, and was called the Adam. Almost no one bought it, though, because the manual so unreadable that the salespeople could not understand how to make it work. Consequently, they never showed it. Consequently, no one bought one. Consequently, the company almost went out of business, saved only by its shift to cabbage patch dolls.

 

[scubaozy]

What agency has removed decompression from their training?

Remove is probably wrong word selection on my part. Not having, separating, excluding probably better.

 

[boulderjohn]

When your computer starts suddenly flashing "up" it can be confusing if you haven't thought about you're doing before hand.

Someone told a story on ScubaBoard long ago about one of the very earliest models of computers. They were trying it out as an experiment. After they were diving for a while, the computer said "dn ob." They had no idea what "dn ob" could possibly mean, so they ignored it. On the surface, they learned that they had the computer upside down. It had actually said "go up."