Dive Computer Brawl

[BillGraham]

I've been using a Nitek 3 for about five years and have never had a problem with it. My only criticisms are that it is bulky compared to the duo, and for most of the diving I do, I'm only using two gases anyway, so I could have really gone with that one. My second criticism is that for wreck diving, where the line is jumping up and down four or five feet when it's rough, it's really hard to get it to switch to 0-2 when it's showing you a twenty foot stop. A Dive Rite rep told me to set the 0-2 percentage to 90 rather than 99, but that bothers me on some level.

As far as the VR-3 goes, I don't own one yet but have played with it a bunch and one of the features I like best is the ability to run out tables with it. That's important when your dive destination gets changed and you need to prepare backup tables away from home, very handy.

I'd like to see it available with RGBM, that's what I'm really waiting for.

I asked Kevin Gurr, with Delta P Technology, if the VR3 is going to be released with VPM, VPM-B or RBGM and if so, when. His response was that they have VPM programmed right now and they are running trials. It’s probably 3 months away from being released. I also asked him if it was OK for me to post the ProDive screen shots and he gave me permission.

[Genesis]

I asked Kevin Gurr, with Delta P Technology, if the VR3 is going to be released with VPM, VPM-B or RBGM and if so, when. His response was that they have VPM programmed right now and they are running trials. It’s probably 3 months away from being released. I also asked him if it was OK for me to post the ProDive screen shots and he gave me permission.

So that's VPM and NOT VPM-B?!

Oh well... there goes my rationale for buying one, especially if its VPM (original) IN PLACE of what's there now, instead of ALONG WITH it.

WHY would they do something like that? Makes absolutely ZERO sense to me!

I didn't ask him the technical details about how they were going to implement it. Hopefully, they will provide an option to choose a decompression model. I like the current VR3 decompression model, but having other choices would be desirable. Yes, it would be nice to have VPM-B instead of VPM.

[Widiver_Paul]

My uninformed opinion is that the VPM-B is so new and dependant on the ongoing feedback is that in it's somewhat "untested" state there may be not enough data to make it reliable for something as dependable as the VR3. I know RGBM is still looked at suspiciously in some circles; I think it's fortunate that Kevin is willing to invest his trust in the VPM algorithm where others just jump in the same boat with the other manufacturers in sticking with only Buhlmann tables (that were experimental themselves not so very long ago). Kudos to Delta P for being vanguards and trying to make diving safer for us. I know lots of divers that were waiting for just this change in a dive computer. It's great we won't have to buy some cheap recreational model to reap the benefits.

[Genesis]

I guess I'll have to wait until someone has one I can look at before plunking down the money....

This much I know for sure - I ain't buying the current model with this one around the corner, given that there's no US-based way to get it updated, and I think its reasonable to assume that the updates won't be free!

I disagree on the VPM/VPM-B point of view. There's nothing at all to stop them from having both available - the current Vplanner code does - and that would make the decision one for the diver to make.

Hopefully they'll put VPM/VPM-B/Buhlmann+GF in there, so you'll have what they've got now, plus the two VPM varients you can choose from. THAT would be nice.

[DeWayne]

My uninformed opinion is that the VPM-B is so new and dependant on the ongoing feedback is that in it's somewhat "untested" state there may be not enough data to make it reliable for something as dependable as the VR3. I know RGBM is still looked at suspiciously in some circles; I think it's fortunate that Kevin is willing to invest his trust in the VPM algorithm where others just jump in the same boat with the other manufacturers in sticking with only Buhlmann tables (that were experimental themselves not so very long ago). Kudos to Delta P for being vanguards and trying to make diving safer for us. I know lots of divers that were waiting for just this change in a dive computer. It's great we won't have to buy some cheap recreational model to reap the benefits.

How do you figure it to be untested? IANTD has been using VPM-B based tables for some time now.

[Widiver_Paul]

How do you figure it to be untested? IANTD has been using VPM-B based tables for some time now.

Just a matter of which one's been around the longest. Up until the last decade we were still using Haldanean models, which are almost 100 years old because they were tried and true...

How do you figure it to be untested? IANTD has been using VPM-B based tables for some time now.

A link for V-Planner VPM-B: http://www.hhssoftware.com/v-planner/

Information on the VPM-B model:
(The information listed below is from
http://www.hhssoftware.com/v-planner/vpmdetail.html ):

VPM-B is a revision by Erik Baker to his original work and the model described below. The change was to include Boyles Law compensation to the ascent gradients that determine ceilings and times of stops. This one additional set of calculations in the model, corrected a number of concerns about plans from the Original model.

The output from a VPM-B profile is a plan that retains both deep stops, and modest amount of time in the shallow areas. A significant amount of diver feedback has confirmed that the VPM-B model is valid across a wide range of dive profiles. From a gentle NDL dive, to a normal double tank deco dive, or a deep CCR dive.

VPM-B is the newest and most accurate bubble model available. The VPM-B model on it's own, produces consistent decompression plans for the entire range of dives, and accurately intercepts the NDL limits as well. VPM-B does not require any modifiers or factors or other mathematical hacks on the input parameters, etc. i.e. no GF's or pfac, bfac, factors, or other trimming methods to arrive at the "right" result.

2002
VPM use in recreational tech diving grows. Model is adapted for use with CCR planning. Diver feedback and documented experiences grow. Initial data suggests the model is valid, but is somewhat range bound. Erik Baker starts work on a revision to the original model (described above). This results in a change to calculating ascent ceilings by including a Boyles Law compensation. Revised model is named VPM-B.

2003
February: V-Planner with VPM-B released at the NAUI Deep Stop conference.
IANTD includes VPM-B tables into all new training courses.
VPM enters commercial work as an approved decompression program with the Danish Maritime Authorities.
V-Planner program further developed to include many of the current tech diving planning features and practices.

[DeWayne]

I've researched the math behind both VPM and RGBM beofre deciding which to trust. The mathematical modeling in VPM is much cleaner and progressive while Bruce relies on older analysis models, which is indeed typical for most physicists. I have found small glitches in RGBM, true it would take a lot of deco time for them to ever make their pressence known, but they are there. Have yet to be able to make the VPM model fail that way. My background btw is in theorectical mathematics, noncommutative algebras and quantum groups.