Padi Advanced OW - Deep stops??

[KenGordon]

The commercially available decompression algorithms are all reasonably conservative, for instance, compared to the US Navy.

You mean like the A1 and A2 profiles from the NEDU deep stops study? Those were so overly conservative according to some they were off the scale of 'normal' algorithms.

 

[scubadada]

You mean like the A1 and A2 profiles from the NEDU deep stops study? Those were so overly conservative according to some they were off the scale of 'normal' algorithms.

This has nothing to do with recreational diving. Please see the extensive discussion in the technical diving forum.

 

[KenGordon]

This has nothing to do with recreational diving. Please see the extensive discussion in the technical diving forum.

You claim that all commercial algorithms are more conservative than all navy ones and I point out that VPM (commercial) is less conservative that Thulman (navy). You made the claim in this forum, it seems fair to contradict it here.

My point, as usual, is that over simplification and generalisation helps nobody.

 

[scubadada]

You claim that all commercial algorithms are more conservative than all navy ones and I point out that VPM (commercial) is less conservative that Thulman (navy). You made the claim in this forum, it seems fair to contradict it here.

My point, as usual, is that over simplification and generalisation helps nobody.

You're out of your mind. All air dives from 60 -130 feet using Navy NDLs have VPM 0 decompression times between 1:55 and 13:30. I used MultiDeco.

 

[scubadada]

Air NDLs

Feel free to post VPM NDLs if you have a planner
? Thalmann US Navy

 

[CuzzA]

Guys I've been looking at the Mares Icon HD computer... Looks pretty cool. Still above my progress credit range... I would actually look into getting that or the shearwater if I wasn't still paying student loans

Hey OP, looks like you got lost in all of this.

I own the Mares Icon. It's a great computer. It's essentially the smart phone of dive computers. It's packed with a ton of great features including AI, compass and color screen. It's the most intuitive computer out there, more so than a Shearwater thanks to its 4 buttons. It's backwards compatible which means Mares continuously updates the firmware/operating system. The next update is supposed to support trimix, so it should grow with you if you ever get into deeper diving. It does run the RGBM algorithm as of now. I don't know if that will change with the addition of trimix. That is one advantage the Shearwater has is the "user" adjustable algorithm of Buhlman 16. That can be a good thing or a bad thing for a new diver or someone who doesn't understand decompression "theory." It does appear pricey at first, but if you keep a close eye on the price at Leisure Pro they will drop it every so often to around $600 including the AI transmitter.

Hope that helps. Don't think you have to run out and make a snap decision on a computer just for the AOW deep dive. Any computer will do.

 

[DevonDiver]

That is one advantage the Shearwater has is the "user" adjustable algorithm of Buhlman 16. That can be a good thing or a bad thing for a new diver or someone who doesn't understand decompression "theory."

The Shearwater Petrel2 and Perdix have a 'OC Rec' (recreational) mode which simplifies many features, including GF options. It's much more suitable for typical novice-intermediate recreational divers, as comprehensive deco algorithm knowledge isn't a prerequisite for use. It still gives flexible options to change conservatism and even decide between one of several safety stop options.

 

[Centrals]

I'm (still) shopping around for wrist computers and would like to know, in the Padi advanced open water course, during your deep dives, did you ever do a deep stop or anything? That way rule in, or rule out choosing a dive computer with that feature.

Deep 6 has a computer on its pipe line for a very long time! The "promised" price is US$139.00 and I have my mind set on it to replace my ageing Uwatec Aladin Pro Nitrox(1997 era). There is nothing wrong with my old computer except the display is fading fast.

I am just a ordinary punter looking for a dive computer and is NOT associated with Deep 6 in any capacity.

 

[KenGordon]

Air NDLs
View attachment 382686
Feel free to post VPM NDLs if you have a planner
? Thalmann US Navy

You should really read and understand the deep stops thread. It is really very interesting between the bickering. The best bits were on RBW though.

A large part of it was about the relationship between the tested NAVY (
VVal-18 Thalmann Algorithm and BVM(3) ) A1 and A2 profiles and VPM7. Vpm7 was chosen because as you make VPM more and more conservative (in VPM terms) eventually it caught up with the proposed deep stop profile. This led to howls from Ross who was saying that the two tested profiles had twice as much deco as necessary, and compared to a typical profile they did.

So which is more conservative? The algorithm which produces more or less deco for the same bottom time?

You also ignore many of the other factors when quoting single dive NDLs as a measure of conservatism. For example many early tables did not support multiple dives per day. One people wanted to do those the tables changed. If you we the through the hoops of planning the ScubaLabs dives with the navy tables you quote how long do you think you'd get on the fourth dive of the day?

NDL times are EXTREMELY sensitive to how a model works. They are no guide to the state of a person getting out of the water having followed a computer. You could be getting out with all your compartments within a whisker of the limit, or with one at the limit and the rest well away. It all depends on the actual profile and the various limits for the different compartments. This leads to some computers having long NDL times (aggressive by your measure) and then long stop times (conservative by my measure) once past the limit.

The other well known (at least taught, but perhaps not scientifically derived) factors such as yo yo profiles, repetitive dives and excessively fast ascents, short surface intervals) factors are not modelled by all computers/algorithms. For a laugh ask multideco to do a very long, but shallowish sawtooth dive. They type your mother warned you about. You will find that the shape does not really matter.

However such dives increase the probability of a bend. So if your algorithm knows that you have not suffered from those events it could chose to allow greater oversaturation without exceeding whatever PDCS it is aiming for.

It is all quite complicated you know. Trying to fit that into some value between 1 and 10 and saying more or less conservative is very unhelpful. In particular comparing table times with actual computer PREDICTIONS is bogus. Tables assume a square profile. That lets them be apparently more aggressive (ie longer NDL) because mostly the dive will not be at the table depth all the way through. Since they are designed to bent a particular proportion of divers ON AVERAGE and on average divers are above the floor they will yield less deco than a computer which knows exactly the depth the diver was at.

What people need to know about a computer:

1 will it kill me? - No, you were going to die anyway.
2 will it keep working? maybe, ask your friends etc.
3 will it limit my diving? yes if you have heaps of gas, never get cold, never get bored, but see 1
4 what does it cost?
5 is it usable?

The actual factors a new diver should consider when buying a computer are not about the algorithm.

 

[Centrals]

......

The actual factors a new diver should consider when buying a computer are not about the algorithm.

I bought my first computer(Uwatec Aladin Pro Air) in 1996. What did I know? Practically ZERO except I did not have to plan the dive with table or wheel any more. I am pretty sure "Bubble""Deep Stop" etc etc did not exist at that time.
Algorithm? I will leave that to computer programmer. I bid good bye to Pure and Applied Maths after A-level. Don't miss them at all. I needed a pile of punch card to use computer back at Univ(early 70s).