New dive computer for Divemaster internship

[Jack Hammer]

For reference, the linked thread illustrates the point myself and others (posts deleted in mod cleanup) were attempting to make about why it is important to have a base level understanding of dive planning/deco theory instead of just blindly relying on a computer.
http://www.scubaboard.com/forums/ac...ncident-due-battery-change-dive-computer.html

 

[KenGordon]

For reference, the linked thread illustrates the point myself and others (posts deleted in mod cleanup) were attempting to make about why it is important to have a base level understanding of dive planning/deco theory instead of just blindly relying on a computer.
http://www.scubaboard.com/forums/ac...ncident-due-battery-change-dive-computer.html

I don't think any responsible person suggests blindly doing anything in diving but that does not imply that diving a computer is a bad idea.

In that other thread the main main mistake was not planning the dive but the bit that might have hurt him was NOT following the computer and thinking he knew better that it.

Ken

Ps I don't know how to rate not actually being able to work either a computer or tables in the league of issues...

 

[SubAquatix]

For reference, the linked thread illustrates the point myself and others (posts deleted in mod cleanup) were attempting to make about why it is important to have a base level understanding of dive planning/deco theory instead of just blindly relying on a computer.
http://www.scubaboard.com/forums/ac...ncident-due-battery-change-dive-computer.html

To be fair, the incident was not due to a battery change, it was due to improper setting on the part of the diver. A battery failure led to human error. For those with the accumen to comprehend and practice deco planning manually, this could have been avoided. For the vast majority, however a computer simplifies things.

In this case, the original poster didn't even take the time to read the manual and learn to use the computer properly, yet you expect them to develop an understanding of correct dive and deco planning.

Not picking a fight, just a different perspective.

;-)

 

[scubadada]

A little research with DAN and other organizations that track incidents might sway you away from less expensive computers.

The reason is that less expensive computers lack the cpu power an memory to process multiple compartments in a timely manner. What they do instead is calculate 3 or 4 compartments, then extrapolate for the 12 or 16 they might be using as a part of the algorithm or model they are using. This could lead to a miscalculation in cases where extents are being pushed. Higher end computers have the capability to calculate for all compartments in a parallel manner in a timely manner.

At your suggestion, I had a very nice, informative, email exchange with Neil Pollock. Regarding your comment on inadequate computing power of inexpensive computers, he said,"I think that we have a translational issue here."

Perhaps you'd like to discuss it with him again. He did have many interesting insights he shared with me.

Very best, Craig

 

[RonR]

....The reason is that less expensive computers lack the cpu power an memory to process multiple compartments in a timely manner. What they do instead is calculate 3 or 4 compartments, then extrapolate for the 12 or 16 they might be using as a part of the algorithm or model they are using. This could lead to a miscalculation in cases where extents are being pushed. Higher end computers have the capability to calculate for all compartments in a parallel manner in a timely manner. <snip>

As a computer designer and algorithm implementer this statement didn’t make any sense to me either, so I suspect there is some misunderstanding. The calculations involved in implementing a Haldane/ Buhlmann algorithm are fairly trivial and would pose no problem to even very low end processors. Dive data just doesn't change that fast. Iterative bubble models are computationally intensive, but I don’t think that is what is being discussed here as only a few dive computers offer that option. In my view, incomprehensible user interfaces are a far bigger problem than poor fidelity to the stated algorithm- which I doubt is an issue in any commercially available dive computer- apart from a well known instance of an implementation error many years ago.


“Tissue compartments” are just mathematical abstractions. When it comes to numbers of compartments in these models, more is not inherently better- it’s possible to calculate and display a level of precision that is not justified by the underlying science. Just as using a micrometer to measure the diameter of a squishy balloon wouldn't give you a more precise size.


All dive computers should be seen as a general guide, they cannot know with any high level of precision what is going on in your body on any particular day. They’re very useful additions to diving, and will track your profiles, even very complex ones, far more accurately than you could possibly do on your own, but when it comes to deco calculations all are using abstracted models.


There is also, for any given algorithm, considerable variation in how it is implemented- how non-standard profiles are handled, what happens if you repeatedly pass through the safety stop depths (which a DM/ instructor could do), are there lock out situations, etc. Much gets pinned on the algorithm that is in fact due to other aspects of the user interface design or to how the algorithm is incorporated into a real time system.

Ron

 

[Lorenzoid]

. . . Iterative bubble models are computationally intensive, but I don&#8217;t think that is what is being discussed here as only a few dive computers offer that option. . . .

That's been my understanding. BUBBLE MODELS are often approximated/extrapolated on personal dive computers, but not a Buhlmann model.

 

[RonR]

That's been my understanding. BUBBLE MODELS are often approximated/extrapolated on personal dive computers, but not a Buhlmann model.

That is correct. Most &#8220;RGBM&#8221; computers, including Suunto, actually run conventional Haldane/ Buhlmann type calculations, tweaked to approximate the results that come from the fully iterative bubble models. These are called &#8220;folded&#8221; algorithms. There&#8217;s nothing wrong with that strategy, it&#8217;s just an efficient use of resources. Fully iterative RGBM, for instance, doesn&#8217;t give you any no-stop times, which recreational divers want and which would require running an algorithm that does provide them. Our Atomic Cobalt uses a folded algorithm until you go deeper than 150&#8217;, at which point fully iterative RGBM kicks in. There may be advantages to the fully iterative algorithm for long or deep exposures, perhaps that's where the confusion comes from. Other computers, including Shearwater and Liquivision and I believe Heinrichs Weikamp, have fully iterative VPM, RGBM, or both available as options. But most recreational computers advertising a bubble model are using a folded strategy.

Ron

 

[para643]

Hi everybody I needyour brain experience from people who knows, first sorry for my English writingI am from Canada/Québec ice diver and French speaking. So I know there is bunchof specialist, tech, and experience diver in this forum. That's why I am here forhelp; the problem I’ve got is that after reading maybe a few hundred pages ondiving computer is that I am more mix up on my decision than before. I am not atech diver but I travel a lot and I dive almost everywhere I go: north, south,warm, cold, fresh, salt water max deep 150ft. Use nitrox and air but normallyair. After all the reading I made a choice of 2 on 6 computer. At first I had the MARESIcon but it seem that is to many problem with transfer data and battery life,next was the Divesoft Freedom it look easy to use in according with the manual,but I've a bad feeling for Ice dive??, X-Deep tap tap computer not for me Océanic VTX maybe .Now I made up my choice on 2 divecomputer the PETREL 2 or SEABEAR H3 that can be also use for altimeter as apilot myself and watch. I know that some of you will said what do you want adive computer or a watch loll. What I want is something good with no problemand reliable in dark cold water and easy to read, getting old eyes. I justregister today on this site to get help and advice on this manner. So forconclusion need advice if you come up witch an order computer I will need agood feedback I don’t want to be more mix up again. Thank you every one foryour comment that you will make, I really appreciate your help .From an honestman, Richard.

 

[MixAddict]

I think you will find the SubGravity H3 powered by Seabear is one of the most technologically advanced dive computers on the market. With extremely easy to read color OLED screen, stainless steel case, sapphire crystal, rechargeable lithium battery via USB cable, 8 gas, Nitrox, Trimix & CCR compatible without any pin upgrades, NFC (near field communications) for easy uploading of your dive log to your smart phone device, all in a very small package that takes up less room on your arm!

I am certainly biased as one of the partners in SubGravity, but I don't think you will be disappointed. You will never outgrow this computer. It works for virtually anyone at any point in their diving career.

Check it out here: https://www.sub-gravity.com/product/subgravity-h3-dive-computer/

Kind regards,
Randy

 

[para643]

Thank you for your comment Randy it is appreciated

Richard.