Shearwater Perdix AI dive log: starting/ending tank pressure?

[stuartv]

I think it would be still be nice to see the actual PG.

But which one? Should they use PADI tables to determine your PG? Or SDI? Or US Navy? Or NOAA? Etc..

That would be nice to have from the aspect of perhaps monitoring the estimated gas at any point remaining through out the dive.

It would also be nice just to save you from needing to either remember or carry some other means of recording your tank pressures.

In other words, I go out on a boat for a 2 tank dive. I don't really want to take pen and paper with me and get it out after each dive to note down the tank's start and end pressures of the dive I just did. If I had a non-AI computer and I could go into the dive log on the computer and enter that data, to have it included in the download to my desktop computer later, that seems like it would be pretty handy.

Since then I have suggested this feature to Shearwater

And you were far from the first to do so...

I have been lobbying them for that plus:

- include all stops that the computer will prompt for in its calculation of Gas Time Remaining. Currently, it will prompt for a safety stop, but it does not include the time you will spend at the safety stop in its calculation of your GTR. It only makes a small difference, but still.

- Continue to display GTR after the computer goes into deco. Since you don't tell the Perdix AI what your tank sizes are, it cannot predict GTR using gases that you have not breathed from yet. So, make GTR only displayed in the case that you only have 1 gas Enabled. If you have more than 1 gas enabled, it can't predict GTR, so don't show GTR at all, in that case. But, if you do have only 1 gas Enabled, then I can't see any reason it should stop displaying GTR at the point you go into deco.

 

[wetb4igetinthewater]

And you were far from the first to do so...

I have been lobbying them for that plus:

- include all stops that the computer will prompt for in its calculation of Gas Time Remaining. Currently, it will prompt for a safety stop, but it does not include the time you will spend at the safety stop in its calculation of your GTR. It only makes a small difference, but still.

- Continue to display GTR after the computer goes into deco. Since you don't tell the Perdix AI what your tank sizes are, it cannot predict GTR using gases that you have not breathed from yet. So, make GTR only displayed in the case that you only have 1 gas Enabled. If you have more than 1 gas enabled, it can't predict GTR, so don't show GTR at all, in that case. But, if you do have only 1 gas Enabled, then I can't see any reason it should stop displaying GTR at the point you go into deco.

Never claimed to be the first. There are issues with people not updating their tank size for if they switch sizes. So I'd just like to see the start/stop tank pressures for now.

 

[stuartv]

Never claimed to be the first. There are issues with people not updating their tank size for if they switch sizes. So I'd just like to see the start/stop tank pressures for now.

Right. And I haven't asked them to add a way to set tank sizes. That *would* make it where it could calculate GTR even when using multiple tanks. But, I don't really see that as a feature that people diving with stage bottles or deco gases would really carry about. So, no tank sizes and GTR that only works for single tank (or sidemount?) would be more than welcome!

 

[Clark Fletcher]

But which one? Should they use PADI tables to determine your PG? Or SDI? Or US Navy? Or NOAA? Etc..

Selectable. Depending on which algorithm you choose to dive.

 

[wetb4igetinthewater]

Not sure if it's really an oversight on Shearwater's part. If it is, Shearwater isn't alone in their oversight. I looked at dive computers from a few different manufacturers when I was looking to buy, and none of them allowed you to see the historical starting and ending tank pressure from the DC itself (only the real time pressure). They all required you to upload the dive history data to a computer to be able to review the dive data in its entirety. I'm guessing there are DCs that allow you to see the historical starting/ending pressure from the DC without having to upload to a computer?

The Aeris A300 CS does.

Out of curiosity, if you could review the historical starting and ending tank pressure from the DC, how would you use that data? I ask because I'd like to know if it would be useful for me to be able to see that information as well.

For tracking gas consumption and dive planning. I use that to compare against my gas consumption swim calculations.

Slightly off topic but, as long as we're talking about available display information, what I'd really like to see a DC be able to do is display your actual pressure group at the end of a dive and after the surface interval. I know that, in planning mode, the DC will calculate your NDL for the next dive based on your previous dive history that day. But, I think it would be still be nice to see the actual PG.

Do you dive a square pattern?

 

[stuartv]

For tracking gas consumption and dive planning. I use that to compare against my gas consumption swim calculations.

I think the point of the question (at least, the point when I thought the same question) was, you can do that by downloading the data DC to a desktop computer. So, how would it help you to be able to see it on the DC itself? Is it just to save you from buying a download cable? Is it for checking your SAC between dives so you don't have to download, for example, on a boat?

 

[wetb4igetinthewater]

I think the point of the question (at least, the point when I thought the same question) was, you can do that by downloading the data DC to a desktop computer. So, how would it help you to be able to see it on the DC itself? Is it just to save you from buying a download cable? Is it for checking your SAC between dives so you don't have to download, for example, on a boat?

I do keep a paper log book, so I'd like to be able to skip the downloading to the dive computer step.

No cable is required as this is done over BT.

There is an app, but it will only provide pressure for the first registered transmitted, but not the second. I also requested an update to the app for that. But I am probably not the first.

 

[Joneill]

I think the point of the question (at least, the point when I thought the same question) was, you can do that by downloading the data DC to a desktop computer. So, how would it help you to be able to see it on the DC itself? Is it just to save you from buying a download cable? Is it for checking your SAC between dives so you don't have to download, for example, on a boat?

I download via Bluetooth to Dive Log on my iPhone right on the boat post dive (can capture the dive site GPS coordinates from the phone into Dive Log as well). With that approach, I can see my start/end pressure and RMV (after I enter the tank size in Dive Log). It works great:

However, I still would like to see the gas pressure info in the log on the DC itself and it looks Shearwater will eventually add that functionality.

 

[NAM001]

But which one? Should they use PADI tables to determine your PG? Or SDI? Or US Navy? Or NOAA? Etc..



It would also be nice just to save you from needing to either remember or carry some other means of recording your tank pressures.

In other words, I go out on a boat for a 2 tank dive. I don't really want to take pen and paper with me and get it out after each dive to note down the tank's start and end pressures of the dive I just did. If I had a non-AI computer and I could go into the dive log on the computer and enter that data, to have it included in the download to my desktop computer later, that seems like it would be pretty handy.



And you were far from the first to do so...

I have been lobbying them for that plus:

- include all stops that the computer will prompt for in its calculation of Gas Time Remaining. Currently, it will prompt for a safety stop, but it does not include the time you will spend at the safety stop in its calculation of your GTR. It only makes a small difference, but still.

- Continue to display GTR after the computer goes into deco. Since you don't tell the Perdix AI what your tank sizes are, it cannot predict GTR using gases that you have not breathed from yet. So, make GTR only displayed in the case that you only have 1 gas Enabled. If you have more than 1 gas enabled, it can't predict GTR, so don't show GTR at all, in that case. But, if you do have only 1 gas Enabled, then I can't see any reason it should stop displaying GTR at the point you go into deco.

Thats is why in another thread is suggested that you use the AI on the final tank you will be on. IE side mount. If you rotation is such that the final tank will be the left one then put the AI on the left one. GTR is there to tell you how long your last available gas will last you.

 

[NAM001]

I do keep a paper log book, so I'd like to be able to skip the downloading to the dive computer step.

No cable is required as this is done over BT.

There is an app, but it will only provide pressure for the first registered transmitted, but not the second. I also requested an update to the app for that. But I am probably not the first.

If your suggestion is accepted then that sensor can not be used on another divers tank. I think that would lead to a problem if not used right.