Apeks DSX TTS logic ?

[Winmit]

soo....does anyone wants to by Apeks DSX...50 dives

 

[Alekseolsen]

Pretty sure it was a design decision, as it's cheaper to implement the simpler algorithm. "TTS" goes on the feature list, and it would be a tiny fraction of buyers who would care about the specifics (single vs multi-gas) AND be able to return it if multi-gas TTS were critical to them.

It's just crazy to me that someone can make a design decision that defeats the main purpose of a dive computer - accurately and "online" provide decompression-information to the user.

Unfortunately the manual have no description of the function, as I almost assumed the deco gases had been switched off or something like that.

 

[ginti]

@Winmit I believe most tech divers plan their dives and the more a diver is advanced, the more they rely on a plan, the less this feature is important.

My perception could be biased, as most of my buddies plan in advance, knows how to make easy calculations (at least in the 0/60m range, no more than 30/40min deco), and the feature you mentioned is just nice to have, period. I wouldn't even bother to look for this feature in a computer, I simply don't need it for now.

Again, maybe it's just a bias, and other divers would pay more attention to this feature, I can't say that for sure.

 

[Winmit]

Alekseolsen​

Nope, i read the manual a few times, i don't see the option. If I haven't added the gas, then I wouldn't be able to switch to it on the stop

Ginti
Well I do plan upfront. I also write down on a slate as backup if I don't have a second tech computer. But the thing is that when I plan I know that i.e. for a 40m deco from depth X I would need approx Y amount of gas. So when I dive when I reach the Y amount I know that this is the minimum I need. If I have exceeded the depth thus making the TTS longer, the gas amount doesn't count. So having both TTS and gas amount give me more flexibility. I know that I should go either when I hit my TTS limit or my minimum gas (ofc with all the needed budy bailout etc calcs, which I have done upfront).
Having shown a TTS of 80m+ when I have planned the gas for a 40mins TTS makes the flexibility of the computer a bit less. In such case I need to plan the "old school" - this depth this time. Over. No flexibiliry

 

[ginti]

Ginti
Well I do plan upfront. I also write down on a slate as backup if I don't have a second tech computer. But the thing is that when I plan I know that i.e. for a 40m deco from depth X I would need approx Y amount of gas. So when I dive when I reach the Y amount I know that this is the minimum I need. If I have exceeded the depth thus making the TTS longer, the gas amount doesn't count. So having both TTS and gas amount give me more flexibility. I know that I should go either when I hit my TTS limit or my minimum gas (ofc with all the needed budy bailout etc calcs, which I have done upfront).
Having shown a TTS of 80m+ when I have planned the gas for a 40mins TTS makes the flexibility of the computer a bit less. In such case I need to plan the "old school" - this depth this time. Over. No flexibiliry

Spoiler: I am going to describe what I do; I don't think that's the right way to do, the only one or anything else - it's just what I do

When I plan, I plan the dive I expect to do, plus several dives at the same average depth but longer (several minutes) to take into account eventual troubles I have to fix underwater. I also plan for increased average depth, in case for whatever reason I have to spend more time than expected on the deepest portion of the dive.

I really, really need to screw it up before being unable to have a clue of the deco I have to do. So much that deco is likely the least important problem at that point.

But this is how I do. I can see the benefit of that function, and I can understand that you don't appreciate a computer without it.

 

[Winmit]

ginti

Yes, i see what you mean. thats more the old-school. totally valid, but why not use the benefits of technologies. Tbh I had same feature I think on even a low tech computer. I think it was so on Scubapro Luna 2.0

 

[dylanfromwinnipeg]

Shearwater has a great blog about a more computer centric approach to managing deco planning that relies heavily on TTS. Evolution of Dive Planning

 

[Umuntu]

Yes, i see what you mean. thats more the old-school. totally valid, but why not use the benefits of technologies. Tbh I had same feature I think on even a low tech computer. I think it was so on Scubapro Luna 2.0

Do you have the computer set to sidemount mode when you get the TTS calculation “error” ?

 

[Wibble]

i was wondering what might be the logic behind the TTS calculation on Apeks DTS. They try to claim it as high tier computer, but I don't see the logic the TTS to be calculated only based on the ACTIVE gas in use. I.e. I set 2 gases - Tx something and pure O2.

If it just shows the TTS calculation based upon the gas you're breathing and doesn't take into account your other planned gases, it's basically useless as a technical dive computer. Only a non-(technical) diver would think this is a good thing as ALL accelerated deco planning is based on switching to richer gases at deco.

It is your dive plan that calculated your dive time maxima taking into account one lost gas. That's not the job of the dive computer but the diver to plan beforehand. (Actually you soon know what the patterns are as you will probably do many similar dives; one 60m/200ft dive is the same as any other 60m/200ft dive for planning purposes)

The other aspect, mentioned above, is that you cannot change the gases underwater. Just imagine you have lost your, say, 100% on the dive and someone gives you their 50% to deco out on. Now you need to program in this unexpected gas so you can safely complete your decompression. OK, how about you are a normal person and you've not changed your deco gas from a previous dive -- most of us are normal, some are superhuman and never make mistakes . You only notice this after a while and need to change this in the computer.

Hate to say this, but the reason people use Shearwater computers is they work like this; allowing you to alter the dive's parameters underwater. This is a serious safety requirement especially on more complex dives.

Finally... There's times when TTS is meaningless. An hour back in a cave/mine, you hit your third, so you've an hour to go back. This is where more complex planning comes in to know you've sufficient gas to deco as well as your third, i.e. you've brought more gas with you.

 

[NX32]

Hi,

i was wondering what might be the logic behind the TTS calculation on Apeks DTS. They try to claim it as high tier computer, but I don't see the logic the TTS to be calculated only based on the ACTIVE gas in use. I.e. I set 2 gases - Tx something and pure O2. Planing my dive I want to quit either on low pressure on tanks or on specific TTS lets say 45mins. While diving an with Tx tank active it give me extremely high TTS based only on the Tx, ignoring that I have added a second gas for deco which would be 02. Of course the moment I reach the gas switch and turn to O2, the TTS is recalculated, but to me it doesn't make sense. When I do my dive planning with all the needed gas etc I have 2 parameters to limit my dive - reaching specific pressure(lets say 2/3 in caves) or a specific TTS, again based on the calculation of the gas I will need to go out.

PS. Generally I do see many other strange decisions in the computer. I tried to address them to apeks asking whats the idea behind, but I never got any answer.

Absolutely, TTS based on a current gas alone makes no sense. I mean it could be a nice additional feature (like lost deco gas TTS or rather worst-case-scenario-TTS).

For example Shearwater calculates „best case scenario” TTS, meaning an optimal deco execution using all programmed gasses for the dive, incl off-gassing on ascent given a of 10m/min rate. Of course, you can modify gasses on lost deco gas.

I’d be really happy to see a worst case scenario TTS though. Sure - when planning a deco dive you have to account for a lost deco gas, but limiting it real time based on current saturation would be awesome. Also, an ideal TTS with an ideal ascent rate and ideal stops is a fiction - imo adding a configurable „conservatism padding to deco execution” in TTS would be cool too, but I don’t think it’s ever gonna happen