'liberal dive computer' for live aboard style high frequency diving

[supergaijin]

Get vPlanner, an SPG, a depth gauge and a watch.

I actually have a Galileo Sol, but don't trust it for anything more than "fun" dives. There's nothing like checking to see where your next deco stop is and for how long, or wondering "how long have I been here?", looking at the computer and seeing a blank screen, or on the SmartCom "E7".

flots

Don't forget the slate/wetnotes and the understanding that you can't deviate from the plan unless you've also planned different contingencies. For multiple dives, your last couple will be very limited using table-based plans.

 

[zf2nt]

I used to have a Uwatec aladin prime (I actually still have it and it work, but "eat batteries") and replaced it recently with a ScubaPro Aladin2G (Uwatec and ScubaPro is the same company) and I dive EAN32. I HAVE been able to getting close to the deco limits, but on those occasions Ive also KNOWN that my profile was rather more agressive than the average dive (and quite often its been on the third deep dive of the day) so it kinda SHOULD be telling me to watch it (which I already did)

If your Aladin Prime is "eating" batteries, you should contact Scubapro technical support about it. There was a run of those computers which had a circuit error whereby the IR section never shut down when the computer was not being used. That would cause the batteries to drain prematurely. Whether your computer was in that run can be determined by the serial number. For a long time, Scubapro was willing to replace any Aladin Prime which was in that run. I'm not sure what their policy is today, but it is worth checking.

 

[Tigerman]

If your Aladin Prime is "eating" batteries, you should contact Scubapro technical support about it. There was a run of those computers which had a circuit error whereby the IR section never shut down when the computer was not being used. That would cause the batteries to drain prematurely. Whether your computer was in that run can be determined by the serial number. For a long time, Scubapro was willing to replace any Aladin Prime which was in that run. I'm not sure what their policy is today, but it is worth checking.

The IR dont turn on, and yes its a known issue. The computer was also 5 years old when this started to happen and the shipping cost, replacement cost (although a very good deal on its own) and waiting time wasn't worth it...

 

[Subboy]

Found this from a review and copying the salient passage below. I'm the OP and this is the type of info I'm looking for. Any disagreements with the author about the algorithms? What dive computers use dsat?
2011 Oceanic VT 4.0 Dive Computer Review | AtlasOmega

One can argue until the cows come home as to which one is “better” (and people certainly do), but the true answer to this oversimplified question is that it depends. DSAT is generally thought of as being more generous to the diver in terms of bottom time, and is more liberal when used during multiple days of repetitive, recreational diving, as is commonly the case during warm water dive vacations when most people try to make the most of their scarce vacation time. The Buhlmann (Pelagic Z+) model is generally considered to be more appropriate for the demands of cold water, decompression and altitude diving, and is typically found in most technical dive computers, such as the Shearwater Predator.

First of all I am new here, Hello to everybody.
I have I doubt about DSAT and Z+ from Oceanic, wonder if you have question it: If you are about to be in a live-aboard doing 14 days of 3-4 diving at around max. 100 ft but but reaching 130 occasionally, with Nitrox 28, and entering some few minutes into Deco, will you choose DSAT or Z+? I don't mind having long time at 6 meters, but don't want to be forced to.

 

[TSandM]

These discussions always make me a little bit uncomfortable, because they seem to verge upon the "magic bracelet" concept. People want a computer to validate what they want to do, and that's not the purpose of a computer. And it is VERY important to realize that NONE of these algorithms have been well validated in the settings where people really want to push the envelope, which is with multiple deep dives a day over multiple days. You can imagine the cost of performing such experiments, especially given that the incidence of DCS is going to be low. The question is, "How low is low?"

I think everybody who does more than a few dives a year really ought to read Mark Powell's Deco for Divers. Understanding not only what is known about decompression, but perhaps more importantly, what is NOT, can be very useful in figuring out where to set your own risk tolerance. It's really key to understand that, as you move to more liberal algorithms, you may very well be accepting a high DCS risk, especially if you don't mitigate it by adopting more conservative ascent strategies.

 

[tursiops]

Found this from a review and copying the salient passage below. I'm the OP and this is the type of info I'm looking for. Any disagreements with the author about the algorithms? What dive computers use dsat?
2011 Oceanic VT 4.0 Dive Computer Review | AtlasOmega

One can argue until the cows come home as to which one is “better” (and people certainly do), but the true answer to this oversimplified question is that it depends. DSAT is generally thought of as being more generous to the diver in terms of bottom time, and is more liberal when used during multiple days of repetitive, recreational diving, as is commonly the case during warm water dive vacations when most people try to make the most of their scarce vacation time. The Buhlmann (Pelagic Z+) model is generally considered to be more appropriate for the demands of cold water, decompression and altitude diving, and is typically found in most technical dive computers, such as the Shearwater Predator.

This is a pretty good overview. For recreational diving, I keep my Oceanic primary (on my wrist) in Pelagic Z+ because (a) my backup only uses Buhlmann, and it is good to keep them in sync, and (b) if I do occasionally go into minor deco, I don't get penalized the way the DSAT algorithm does.

---------- Post added February 5th, 2014 at 04:50 PM ----------

CNS O2 exposure

Several have mentioned this in their posts. The Oceanic computers track O2 exposure per 24 hour period using the NOAA table and give no credit for surface intervals. It is entirely possible to reach 80% or even to exceed 100% when one is diving 4 or 5 dives per day on nitrox, especially multiple days.

I'd be interested to hear if other computers give surface interval credit and whether this credit uses the 90 minute half-life often stated for oxygen

I'm not sure this is true. i sat down with the tables once and tried to construct a sequence of no-deco dives that would end up "breaking the NOAA O2 clock," and could not easily do it. For example, 40 mins (NDL, max BT) on 36% at 90 ft gives you 60% of the allowable 24h O2 exposure, but after an hour SI the 2nd dive only gives you 20 mins NDL at 90 ft (because of 20 mins of residual N2) and that only gives you another 15%. After another hour SI the 3rd dive only gives another 15%, so you'd have to have four dives, all on 36%, all to NDL at 90 feet, to break the clock. On 32%, it would take 9 dives (with 1h SI) to 110 ft (the MOD) at max BT to break the clock. Since 36% is getting harder and harder to find at resorts and on liveaborads, I'm not sure the O2 clock is a primary limiting factor.

---------- Post added February 5th, 2014 at 04:53 PM ----------

First of all I am new here, Hello to everybody.
I have I doubt about DSAT and Z+ from Oceanic, wonder if you have question it: If you are about to be in a live-aboard doing 14 days of 3-4 diving at around max. 100 ft but but reaching 130 occasionally, with Nitrox 28, and entering some few minutes into Deco, will you choose DSAT or Z+? I don't mind having long time at 6 meters, but don't want to be forced to.

See my first answer above. If you expect to go into deco, Z+ will do a better job for you. if you can totally avoid deco, DSAT is fine. Nothing is going to force you to spend a long time at 6m (or more likely 3m) unless you really go into deco, regardless of your algorithm.

 

[fnfalman]

These discussions always make me a little bit uncomfortable, because they seem to verge upon the "magic bracelet" concept. People want a computer to validate what they want to do, and that's not the purpose of a computer. And it is VERY important to realize that NONE of these algorithms have been well validated in the settings where people really want to push the envelope, which is with multiple deep dives a day over multiple days. You can imagine the cost of performing such experiments, especially given that the incidence of DCS is going to be low. The question is, "How low is low?"

Yep, just because the computer said that you're not in deco, it doesn't mean that you wouldn't get the bend.

Whatever algorithm you use, know your NDL and stay well away from it.

I want to be an old diver and not a bold diver.

 

[tursiops]

I *am* an old diver, now bold is all that's left!

Sent from my ASUS Transformer Pad TF700T using Tapatalk

 

[Divenomad]

There are a few good answers here, looking at the problem multiple ways, I like this one the best. Invest in your knowledge base.

That said, Tursiops comment about DSAT for no deco and Pelagic Z _ (Buhlmann) for deco distills a lot of information, theory and lots of discussions down to the essential information. It's a very good short answer.

These discussions always make me a little bit uncomfortable, because they seem to verge upon the "magic bracelet" concept. People want a computer to validate what they want to do, and that's not the purpose of a computer. And it is VERY important to realize that NONE of these algorithms have been well validated in the settings where people really want to push the envelope, which is with multiple deep dives a day over multiple days. You can imagine the cost of performing such experiments, especially given that the incidence of DCS is going to be low. The question is, "How low is low?"

I think everybody who does more than a few dives a year really ought to read Mark Powell's Deco for Divers. Understanding not only what is known about decompression, but perhaps more importantly, what is NOT, can be very useful in figuring out where to set your own risk tolerance. It's really key to understand that, as you move to more liberal algorithms, you may very well be accepting a high DCS risk, especially if you don't mitigate it by adopting more conservative ascent strategies.

 

[redacted]

I have done shorter live-a-boards with similar diving (4 or 5 dives a day in the 100 ft range) on 32%. The problem you need to watch is after the first couple days, you will see slower tissues take over as the lead compartments. Those compartments may still loading even when you are fairly shallow (40 ft) and they are real slow off-gassing so you could hit some longer deco requirements, especially if you try to add in an extra safety margin. I have spend 10 minutes at 10 feet just to drop another tick on an older Oceanic 15 tick TLBG where each tick is about a 6% load. I would not plan on running up any deco obligation with that much diving planned.