Mass confusion about computers????

[arew+4]

Rodale's scuba diving used to do side by side computer tests in a chamber/pressure pot. And apparently still does. Not sure if it's ok to repost this here. Mods?

 

[runsongas]

if you don't want to go used, a genesis react pro is 215 at LP. should be able to call them up and get a discount. add a dss boot and it is in the 200 dollar ballpark.

2 buttons and dsat. no bluetooth though.

 

[Eric Sedletzky]

I’m not really worried about bluetooth or downloading dive profiles. You have to realize I’ve been running tables in my head for years on and off between some computer use. I’m just now retiring my bottom timer.

I’m also not worried about spending a little if it’s worth it. But I think it’s silly to buy something loaded with features that l’ll never use just to get a decent algorithm. I’m looking for something like the Shearwater but without all the needless features. Tbone actually had a good comment to buy a used one, but I’m not sure I’m comfortable buying used electronics....still on the fence about that.
I used to have a Suunto wrist computer years ago (Vyper I think?) and my then dive buddy was using an Oceanic. The Suunto gave me less bottom time than his Oceanic on the first dive, but then he would get dinged on the second dive and the Suunto was actually a little more liberal on subsequent dives.... to a point.

I could and will do all sorts of research on this, but information about computers seems to change faster than I change my underwear, so I just figured I’d start a fresh thread here on SB to get a current perspective.
And if in the end Shearwater is where it’s at, then so be it.

Whatever it is I get, I’m looking forward to using the Mares side by side with it and bending the Mares so bad that it looks like a pretzel.

TMI, drives me nuts!!

 

[BoltSnap]

These computers are the best value for the entry to mid level recreational diver (and even more but without AI):

1. i300C Dive Computer - Aqua Lung US - Recreational and Professional Scuba Diving Gear (this is a newer version of the i300. It is i300C with Bluetooth connectivity and backlighting).

2. Aladin Sport Matrix Wrist Dive Computer | SCUBAPRO

3. i100 Dive Computer - Aqua Lung US - Recreational and Professional Scuba Diving Gear (least expensive AL computer without Bluetooth or backlighting)

4. The Oceanic Veo 2 wrist: VEO 2.0

AL, Oceanic and SP all offer wrist sized dive computers for much more money not in the above list.

I would NOT consider any compute from Mares, Cressi (even if given for free) or Suunto anymore at all.

For Advanced rec./tech with AI:

1. Shearwater

2. Ratio

3. SP G2

(I have been using Ratio for myself the last few months and I love it)

 

[scubadada]

Hi @Eric Sedletzky

There are less choices than you would think. See So what's the word on the $195 Aqua Lung i-100 ?, post #28 for links to ScubaLab testing, repetitive dives, data also referenced by @arew+4 above. The most popular computer brands are listed below, with my classification of their decompression algorithm as liberal, moderate, or conservative. Any errors are all my own :

Aqua Lung manufactured by OEM Pelagic Pressure Systems owned by Aqua Lung, runs PZ+, moderate

Atomic runs Atomic RGBM, liberal

Cressi runs Cressi RGBM, conservative

Divesoft runs Buhlmann ZH-L16C with custom GFs, variable from conservative to liberal

Garmin runs Buhlmann ZH-L16C with preset and custom GFs, variable fom conservative to liberal

Genesis manufactured by PPS, runs DSAT, liberal

Mares runs Mares RGBM, conservative

Oceanic manufactured by PPS, runs both DSAT and PZ+, liberal and moderate

Ratio runs Buhlmann ZH-L16B with preset and/or custom GFs, variable from conservative to liberal

Scubapro runs Buhlmann ZH-L8 ADT MB or 16 ADT MB, moderate

Shearwater runs Buhlmann ZH-L16C with preset or custom GFs, variable from conservative to liberal

Sherwood manufactured by PPS, runs DSAT, liberal

Suunto runs Suunto RGBM, conservative (DX, Eon Steel and Core run Fused RGBM, can be liberal)

Tusa manufactured by PPS, runs PZ+, moderate

Edited 2-16-18 based on comments

 

[BoltSnap]

I’m not really worried about bluetooth or downloading dive profiles. You have to realize I’ve been running tables in my head for years on and off between some computer use. I’m just now retiring my bottom timer.

If Bluetooth or backlighting aren't important for you, then the AL i100 is the best value for you: i100 Dive Computer - Aqua Lung US - Recreational and Professional Scuba Diving Gear

 

[tbone1004]

@Eric Sedletzky so the "needless" features that you have on the Petrel

Hardware:
Maybe bluetooth? other than that none

Software:
trimix and CCR- that's just a software bit and you can run the Petrel in recreational nitrox mode
Multi gas-probably not that big of a deal, but it's easier to turn gases on and off than it is to change gas mixes. i.e. leave Air, EAN30, EAN32, whatever gases you use regularly and turn them on and off as needed.

Buying used on the Petrel isn't a problem. Not a whole lot to go wrong and Shearwater actually stands behind their stuff if something goes sideways. I've had my Petrel 1 for 4 years with no issues. Buddy bought one used and out of warranty and had an issue with the battery compartment and they fixed it for the cost of shipping.

 

[Steve_C]

2. Aladin Sport Matrix Wrist Dive Computer | SCUBAPRO

I was diving a Zoop and a Aladin Sport and have switched to two Aladins. ON 60-90 ft dives Zoop and Sport were about the same on dive one. On the second dive Zoop was giving me 15 or more fewer minutes of NDL

 

[dmaziuk]

I bought an Mares Puck a few years ago figuring that it was just a simple basic computer that did everything I needed including nitrox, user battery change, guage mode, auto turn on , etc.
What I didn’t know at the time that I’m reading now is how rediculously conservative they are even to the point of being a nuisance.

Has it been a nuisance to you on your dives?

Is there some sort of resource someone can direct me to with a table or graph that might list the different computers and where they sit on the conservative <> liberal scale?

The ones that exist are garbage. There is no good way to access "conservatism" of recreational-type computer past the "DSAT is most liberal, RGMB is most conservative, PZ+ is somewhere in-between" -- you don't need graphs for that.

If you want details, a DC calculates NDL at current depth from current gas loading. If you stay at current depth, your loading changes. If you move, both your depth and loading change. Either way, next time the DC recalculates your NDL, it's gong to be different. Dep. on the number of tissue compartments in the model, different DCs may have a different idea of what the leading compartment is, and whether it's on-gassing or off-gassing at any given point: two minutes later one DC may recalculate you "more" NDL, another: "less". Bubble-based ones compute bubble growth from delta pressure over time and will appear more conservative if you come up too far too fast (for their liking), while non-bubble models may lock you out for "gross violation of safe ascent rate" but ignore your ascent profiles otherwise. Too much bubble growth may affect the programmed off-gassing rate (who knows how they're really programmed) and then you'll get more residual loading after the same SI compared to a non-bubble DC. Which will of course affect your next dive.

It's really too hard to quantify the differences, and picking a few random points on a few random profiles as if they mean anything, can't possibly make any sense to anyone who understands how computers actually work.

 

[dmaziuk]

I was diving a Zoop and a Aladin Sport and have switched to two Aladins. ON 60-90 ft dives Zoop and Sport were about the same on dive one. On the second dive Zoop was giving me 15 or more fewer minutes of NDL

Was that 16 vs 1 at the bottom, or 99 vs 84 at the SS? One of those is not quite like the other. Think about it for a second and I'm sure you'll realize that the statement is meaningless without that little detail.