Mk2 Descent?

Throughout your last several posts, you’ve stated that you have only lost your signal a few times (1 in every 25 based on your last post). Then you tried justifying that, that was ok because you knew someone that had an SPG that malfunctioned (or was misread). Am I missing something here? Can malfunctions happen? Absolutely, but the likelihood of it happening (SPG failing vs a wireless signal) is drastically less.

I need to correct the misleading information here.

I didn't say 1 in every 25. I said that I've had on average one lost signal in every 25 dives. I then went on to say that the signal comes back in under a minute. So that's less than one minute of lost signal over the full length of 25 dives. I also said that when the signal is lost, the Perdix displays the last tank reading. i.e. the reading is less than a minute old.

Let's see what that actually means from a practical perspective.

My average dive time for the last few years is around 90 minutes. So 25 times 90 is 2,250 minutes. So I've not had a signal for less than a minute for 2,250 minutes of dive time. that's less than 0.04%.

Now, my SAC various from around 0.6 to 1.5 bar/minute. Let's assume the worst case of 1.5 and I'm diving at 20m. That's less than 5 bar that the Perdix would be out. The few times I've seen it happen it was actually 1 or 2 bar but even if it was out by 5 bar that is still more accurate and more precise than you get out of a analog SPG.

To summarise: For >99.96% of the time I'm diving, my Perdix is accurately showing the pressure in my tank. For <0.04% of the time it is showing me less accurately but still more accurately than an analog SPG.

Seems like a non-issue to me (and the tens of thousands of other divers using wireless AI).

It appears that someone’s a little sensitive right now, hence the need to create another follow up post. So I wouldn’t read my next sentence then...it’s abundantly obvious that you have a comprehension problem. I never said for someone NOT to use a wireless computer. What I said and haven’t strayed from was that a computer/SPG (non-air integrated) with a hard line directly to the HP port on a 1st stage is the SAFEST (see these big letters? I used this word several times in my posts) option for people, since at no time are you relying on a wireless signal.

You can go back and attempt to justify things in your posts, come up with mathematical equations to justify how little your signal is actually lost (which if you sat back and actually thought about it, in a life support sport isn’t one time to many?).

Anything hard lined vs wireless will always be more reliable.

/back to topic hibernation

Problem with 90% of diving professionals is that their instructor cert is the highest degree they got. The level of discussion shown here fits the bill nicely.

If an AI failure gets you into the life threatening situation, something is wrong with your dive plan to begin with.

profunditas Thank you for your insightful post, it’s greatly appreciated. As always, thank you for your monthly contribution to this forum.

Regards,

Uneducated Forum Member

It appears that someone’s a little sensitive right now, hence the need to create another follow up post.

And it is clear to everyone that someone is you. You were the one that said you wouldn’t post again and yet here you are posting again. TWICE. I’m happy to continue this discussion as I know I’m right.

So I wouldn’t read my next sentence then...it’s abundantly obvious that you have a comprehension problem. I never said for someone NOT to use a wireless computer. What I said and haven’t strayed from was that a computer/SPG (non-air integrated) with a hard line directly to the HP port on a 1st stage is the SAFEST (see these big letters? I used this word several times in my posts) option for people, since at no time are you relying on a wireless signal.

No comprehension problem here. You have a logic problem.

You took it further than just wireless AI not being the SAFEST option.

For example:

I never bring in AI computers into my store as people lose connection often. They may know their depth but not knowing PSI is an issue...

Basically you saying won’t sell wireless AI devices because you don’t trust them. You are implying they are unsafe. This is the part I am arguing.

Your logic goes: Connected is safer than wireless, therefore connected is the safest option. But you go on to imply that wireless is not safe or at least because it is not the SAFEST option you won’t use it.

Others quotes include:

AI has its place BUT in your post you mentioned two AI computers and with both you mentioned that you have lost signals before, no matter how long, you still lost it. One time is too many in my book.

You can go back and attempt to justify things in your posts, come up with mathematical equations to justify how little your signal is actually lost (which if you sat back and actually thought about it, in a life support sport isn’t one time to many?).

“One time too many” implies it is not safe. i.e., you aren’t just saying it is not the SAFEST option, you are implying it isn’t safe.

Now, you also said:

So if I recommend something or say something, it’s because it is the SAFEST option for people.

You use that statement to justify recommending against wireless AI. You don’t follow that same logic in other areas.

I applied your exact same logic to diving itself. Not diving is definitely safer than diving. Therefore, not diving is the SAFEST option. And yet you are not choosing the SAFEST option. (Note that I’m not saying that diving is unsafe per se but just following your logic and using an extreme example to demonstrate how how flawed your logic is.)

How about a different example? Diving to 18 metres is safer than diving to 30 metres. Therefore, diving no deeper than 18 metres is the SAFEST option. Do you teach people to dive deeper than 18 metres, even though it is not the SAFEST option?

I could give many more examples.

I’m not even sure I agree that an analog SPG is the SAFEST option.

Wireless AI is safe and reliable. While the signal can be lost, it is uncommon (when configured correctly) and inconsequential.

Wireless AI also means that divers can see both their depth AND their tank pressure in one go (plus gas time remaining, etc.) As I have already said, divers with wireless AI will know their tank pressure more often and more reliably than people using analog SPGs.

So the benefits that wireless AI bring make it safer than analog SPG in many instances.

I guess the true SAFEST option would be wireless AI AND an analog SPG. Overkill, yes, but definitely safer than either on their own. Why aren’t you recommending that?

Yikes, this seems to be going off the rails.

I get asked by a lot of students about what dive computer to use, and if they should use AI or not. First off I tell them to always get an SPG, and if they want to use a dive computer with AI to go for it but keep the SPG as a backup. I always tell them that AI is the least reliable way to monitor their tank pressure and should not be used with a backup.

Trust me, you’re not dispelling any MYTHS. I sell these things for a living, it’s my job to know more about them and what the SAFEST option is for divers, not the most “convenient”.

I’ve sniffed around SB before, as I know you post there as well. You don’t change people’s opinion, you can only change your response. I could care less trying to convince about changing a vet diver but I will convey my opinion to a new diver because they don’t know or understand...and because I’m 100% right ; )

I am on the side of Odie, I would also use a AI only with a backup SPG.

I am eagerly awaiting the Mk2 and hope it has air integration. I also firmly believe thatair integrated computers are SAFER than non-AI computers. Crazy talk, I know. So why do I think that?

Imagine a diver, let's call him Scuba Sam, that has all of his equipment* and is looking to buy a dive computer. Sam has two choices the Mk1 or a hypothetical Mk1+ that is identical to the Mk1 in every way, except it is air-integrated. Which option is safer?

Now say I told you Sam's equipment includes an SPG. So his two choices are diving with (1) an SPG and dive computer without AI, or (2) an SPG and a dive computer with AI. Adding AI increases redundancy, provides better air consumption data during the dive (air time remaining), and is generally more convenient. The AI option does add another failure point in that the transmitter might break in such a way that it causes a HP air leak. The non-AI model reduces that unlikely risk of a HP leak at the cost of giving up redundancy and additional dive data. In this scenario, AI is generally safer (the leak risk is very low vs the redundancy benefits).

Now let's say I told you Sam was an old-timer used to diving with J valves and never bothered to get an SPG and he doesn't like the clutter of an SPG. Now the two possibilities are diving with (1) no SPG and a dive computer without air data, or (2) no SPG and an AI dive computer that gives him air pressure. In this case, adding air integration is much safer. Of course this is an edge case.

So, keeping all other equipment the same, having an air-integrated computer is safer than non-air integrated.

The real question is, "If one has an air-integrated computer, how safe is it to remove the SPG". The issue isn't around the safety of the AI at all. The issue is around the safety of removing the SPG. I think everyone on both sides of the conversation so far would agree that it is objectively safer to keep the SPG when you have air-integration.

Then it is a matter of personal opinion on if the trade-off in reducing clutter/hoses is worth the reduction in redundancy (and safety) by removing the SPG. I personally keep the SPG. But I understand that is a personal choice.