MacDive Forums

Hi. Thanks a lot for a truly amazing app, and especially lately when it has become a lot more tec-dive friendly! I just LOVE new deco profile for example!!

I have a request however. Is it possible to record the "current gradient factor" when surfacing? Like the new SurfGF on the Shearwater computers just as you break the surface? Or what the GF99 reads as you break the surface.

I don't know if this information is available even, but it would be really great!!

Thanks again!

The specified high/low GF could be recorded separately, and will be in a future version. They are already currently recorded as part of the deco model though, if you look at that field (in the table, or under Gases in the Inspector).

Hi.

Yes I know that the high/low GF is recorded as the deco model. What I'm referring to is: if you set your GF to 40/80, and you surface at the exact time the computer says you've cleared the deco, you'll have surfaced with a "realtime" GF of 80. But if you stay for 10 more minutes before surfacing, you may have a "realtime" GF of 73 for example. And if you were to surface too soon, maybe you surface with a "realtime" GF of 120.

Basically what I'm looking for is to record the "GF99" at the time you break the surface.

My mistake, I'm not familiar with this. I would need to check the documentation to see if it's available. If so, I will look in to it when I can.

Hi. Don't know if this is something you've looked into yet, but the Shearwater software now have the GF99 as part of the graph, and the SurfGF as you break the surface is displayed in a data field. Don't know if it change anything for MacDive, but I just assume that it's information that's available then, since they can show it.

It's probably not something that's high on your priority list. It's however a value that's kind of interesting, especially for more extended decompression diving and comparing to the level of fatigue etc post dive. It may be a lot of work to implement though.

I am using HW OSTC2c ZHL-L16 GF. In the advanced page of gases inspector, Set point High and Set point Low are automatically set to 0 and not at the selected value of the computer.
Sergio Fantaguzzi

Hi Sergiofa, Nick might be able to help with your problem, but it's not what this thread is about. This thread concerns a wish for a new feature where I'd like the software to store the theoretical value of tissue loading/supersaturation upon surfacing. The Shearwater computers call this value "Surf GF" or "GF99".

Except for while at the surface GF99 and Surface GF is two different things.

sergiofa wrote: ↑Sun Dec 29, 2019 6:16 pm I am using HW OSTC2c ZHL-L16 GF. In the advanced page of gases inspector, Set point High and Set point Low are automatically set to 0 and not at the selected value of the computer.
Sergio Fantaguzzi

They weren't being set at all. I have updated both macOS and iOS to (hopefully - untested as I don't have any data) add these correctly.

ManateDiver wrote: ↑Tue Jan 07, 2020 6:52 am Except for while at the surface GF99 and Surface GF is two different things.

Okay, that's interesting! How are they different? As I understand it:

GF99 is a calculation of what your theoretical level of supersaturation is "right now" in the leading tissue, and will increase as you ascend in the water column.

Surf GF is a calculation of what your theoretical level of supersaturation would be in the leading tissue compartment if you were to instantaneously go directly to the surface.

Under water they are obviously different, as Surf GF decrease during decompression, and GF 99 increase as you ascend. But they should both be the same once you are above the water? Should they not?