Computers with non-conservative algorithm.

[BoltSnap]

To Original Poster, get yourself an Oceanic.

 

[Centrals]

Sooner or later NAUI, SSI, PADI etc will run a course on "understanding your computer algorithm".

 

[stuartv]

Oceanic DSAT is basically the PADI RDP, even per Oceanic, i.e. optimized for things like liveaboards, or Caribbean diving. Comparing it to Buhlmann on the first dive is unfair because what they have not told us is how the computer works for repetitive diving. DSAT uses a completely different method to calculation tissue loading than the Buhlmann algorithm they used to make PZ+, but again, we don't know what their conservatism levels mean or what they equate to in a public algorithm. Do I use DSAT even though on the first dive it roughly matches Buhlmann GF99, but on the third dive of the day it's going to GF70 *I have no idea what it actually ends up looking like, was just a random number*. The difference here is on how they choose to track the slow tissues and which tissues they favor. Are they trying to prevent bubbles in the fast tissues but that comes at the expense of the slow tissues still ongassing? *all bubble models, and a Buhlmann algorithm with a low GF Lo which will quickly shorten your repetitive dives but not really impact your first dive*, or do they find a more balanced or slow tissue bias where they try to get you shallow quick in order to minimize on gassing of the slow tissues?.

@scubadada has been diving with DSAT for a long time. More recently, he added a Nitek Q to his wrist and has been actively diving and comparing DSAT to using GF. Maybe he will pop in here and shed some real world light on how DSAT compares to using GF for repetitive dives.

 

[scubadada]

@scubadada has been diving with DSAT for a long time. More recently, he added a Nitek Q to his wrist and has been actively diving and comparing DSAT to using GF. Maybe he will pop in here and shed some real world light on how DSAT compares to using GF for repetitive dives.

I have 1200 dives using DSAT since 2002. Most of my dives are within recreational boundaries, about 5% have light deco, <15 min. This is a proprietary decompression algorithm, the details are not all in the public domain. Some of the characteristics are available, in Mark Powell's Deco for Divers, as an example. DSAT is among the most liberal of the commercially available decompression algorithms. The Cochran algorithm, similar or identical to the US Navy algorithm, is more liberal. A thread like this is difficult to respond to because the topic is reasonably complex and not amenable to sweeping generalizations.

I have recently been diving a Dive Rite NItek Q as a backup to gain experience with Buhlmann ZHL-16C with GF. This replaced my very trusty Oceanic Geo2 that I had been diving for more than 5 years. My primary is an AI Oceanic VT3. In general, it takes a GF hi of 95-100 to match DSAT. It is interesting that the relationship is not simple or linear. Shallower dives are more like a GF hi of 95 and deeper dives are closer to 100. The nitrox mix also makes some difference with nitrox requiring a somewhat lower GF hi than air. I disagree with one of the previous comments, there appears to be absolutely no penalties for repetitive dives dives using DSAT relative to ZHL and GF. This is very different than any of the RGBM algorithms, such as those used by Suunto, Mares, or Cressi. These algorithms appear to penalize for rapid ascent, short SI, reverse profile (now debunked), and multiday diving. DSAT appears to pile on shallow deco once the boundary is breached. It is not at all clear how DSAT handles deco and the algorithm was developed for recreational diving. ZHL and GF will give you a deco profile somewhat dictated by the GF lo you have chosen.

For my style of relatively aggressive diving, I have found DSAT to be perfectly acceptable. One is able to easily mimic a DSAT like profile using ZHL with a relatively high GF hi setting. An advantage of ZHL is that you can tailor your profile the more you vary from a recreational profile. My next primary computer will be an AI running ZHL, as soon as someone makes one that meets my specifications. Stuart's Hollis TX1 has a maximum GF hi of 90, eliminating it as a possibility for my recreational diving, too conservative.

 

[BoltSnap]

Sooner or later NAUI, SSI, PADI etc will run a course on "understanding your computer algorithm".

This is very well possible, a specialty course to discuss all details of this topic. For NAUI, this is covered in our NAUI Master Diver course and in the technical courses.

 

[Centrals]

This is very well possible, a specialty course to discuss all details of this topic. For NAUI, this is covered in our NAUI Master Diver course and in the technical courses.

From time to time I had came across divers who did not have a clue what their own computers had been telling them! The computer is flashing, the alarm went off etc etc. If those divers found it too troublesome to read the manual what is the chance for them to take even a casually glance on the theory of the algorithm used in dive computer.

 

[BoltSnap]

From time to time I had came across divers who did not have a clue what their own computers had been telling them! The computer is flashing, the alarm went off etc etc. If those divers found it too troublesome to read the manual what is the chance for them to take even a casually glance on the theory of the algorithm used in dive computer.

Actually, NAUI Scuba Diver course (the entry level course) includes teaching all required information for dive computers in addition to dive tables. We teach all basic terminology and basic use of computers. It is in the textbook, instructor guide and exam. I am going further this year by training my students on the actual use of dive computers during their training dives. Each student has a dive computer to use during his training dives in addition to dive tables use and training.

We do NOT go into algorithms with detailed discussions however. This is left to future courses (MSD).

 

[gopbroek]

Hello, I am looking for a new computer with a non conservative logarithm. Recommendations?

Back to the original question the Oceanic DSAT is probably what you are looking for. With the newer Oceanic's the dual algorithm units have a selection DSAT or Pz+ so this gives you flexibility to adjust to the type of diving you plan to do. Oceanic also owned the Aeris brand and those computers came out of same manufacturer (Palegic Pressure Systems) but the Aeris line has been folded back into Oceanic. There is still inventory of the Aeris computers for sale and Oceanic supports and warranties them. The Aeris A300 is the equivalent of the VEO 3.0 and can be had off Amazon for $199.
If you can wait a bit Deep 6 gear is supposed to release a dual algorithm computer running either RGBM or GF for around $140.
Black Friday is just around the corner, I would expect a lot of deals and new product release's to come up.

 

[BoltSnap]

Just to note that Oceanic computers not only run dual algorithms with differing conservatism factors, they also give you the facility to adjust the "conservatism" factor after you have set the algorithm you want to use. In other words, the conservatism adjustment is wide ranged in the Oceanic computers.

 

[Basking Ridge Diver]

In other words, the conservatism adjustment is wide ranged in the Oceanic computers.

This blanket statement is not correct. The VEO 2.0 is an on / off for conservatism - you can not adjust conservatism in a wide range. If you buy a computer make sure you know what you are getting - that said I own an Oceanic and I like it.