Question for those using a petrel/perdix. Mode and nitrox % quickly

[inquis]

leaving 18/45 or 99 activated for a recreational profile (!) will dork up the computations.

This is incorrect if you actually mean "available" rather than "active". (Various posters above have conflated those two terms.) There is zero issue having various gases defined & available (i.e., ON in the gas menu) on an NDL dive, and it is quicker to select your single gas from the pre-defined choices. Also, NDL is based on the *active* gas, and all others are ignored until NDL is exhausted. As far as I can tell, the OP is doing NDL dives on a LOB.

While I don't think it applies to the OP, even when mandatory deco stops kick in, ceilings/stop depths are computed with the active gas. Follow those and your profile will be identical to one where the actual gas is the only one defined or whose status is set to ON.

 

[Searcaigh]

For recreational diving why not just use the computer on 3-gas Nitrox?

My go to gases locally are 21, 34 and 40 and I switch off what I'm not using.

 

[JMarc]

While I don't think it applies to the OP, even when mandatory deco stops kick in, ceilings/stop depths are computed with the active gas.

There are 3 kinds of gas.

Configured, but not enabled.
Enabled.
Active (and there's only one active).

TTS is displayed assuming that you switch to be best enabled gas.

You can switch gas to any configured (enabled or not).

I haven’t tried to modify the gas configuration under water.

 

[JMarc]

For recreational diving why not just use the computer on 3-gas Nitrox?

I prefer the display of OC Tech.

 

[TT_Vert]

In Maldives I got one Nitrox mix at 29%. I just left my setting on Nitrox 32% rather than add in a new profile. I have 3 of the 5 profiles setup. I have had my Perdix in OC Tech mode since I bought it. Shearwater has done really good things to allow me to have what I want on the main screen.

@TT_Vert a dive buddy of mine just started using a Perdix but had been using oceanics for years.
At first he too thought the OC Tech mode was a litte frustrating but he saw how quckly I could setup his Perdix. IT was a case of knowing my Perdix and what the firmware has.

Now he if more familiar he loves how quickly he can get in OC TEC mode what he needs. He did need also to learn about Gradient Factors, Surf GF, GF99, and also understand when in Deco the TTS and what cealing was when that showed up. We did several deco dives together in Marldives in May and we use the same GF settings. So then we could compare dive profiles after uploading out dives.

Your issue really is not using your Perdix for five years, updating to new firmware and now there is a lot to learn. It takes time but your issue is not being familiar with the new firmware. A minute or two of setup time is just doing a pre dive check. Yeah and dont setup 1.6 when everyone else is on 1.4.

So deep dives are to 40m then? LOB should be able to mix 27% Nitrox which gives you a safe depth to 40m.

I'm not sure of depths yet but I'm hearing over 100' in some areas. Not a fan of deep dives IMO but I've done my fair share. I have been researching the delta and @+5 as well as SurfGF and GF99. Looking at subsurface (my logging app) I've always logged SurfGF and GF99.

Dave

 

[inquis]

TTS is displayed assuming that you switch to be best enabled gas.

True, but we don't ascend from a mandatory stop based on TTS. It won't change the stop depth until tissues are able to tolerate the next depth, and tissues are calculated with the currently active gas.

OP, my apologies for straying from your NDL scenario (although that is an assumption on my part).

 

[NothingClever]

What features in OC Tech are necessary during a recreational profile?

I dug into my files and remembered Shearwater produces a completely separate manual for the use of the Perdix in Nitrox Recreational mode.

There must be a reason for that.

 

[Blackcrusader]

What features in OC Tech are necessary during a recreational profile?

Surf GF, GF 99, PPO2 information and deco information. Deco diving has always been part of recreational diving for many agencies. I no longer use the low NDL alert which I had set 2 mins before deco. I turned that off now.

 

[Blackcrusader]

I'm not sure of depths yet but I'm hearing over 100' in some areas. Not a fan of deep dives IMO but I've done my fair share. I have been researching the delta and @+5 as well as SurfGF and GF99. Looking at subsurface (my logging app) I've always logged SurfGF and GF99.

Dave

Well 100 feet or 30m is fine with 32% the MOD is not reached. Also the Perdix does not have audio alarms so you set your Perdix with colours for the alarms. As in the photo I posted above on the LOW NDL alert. Was also the max depth for the deco I had at 32%

Unfortunately shearwater app does not show the Surf GF on its app only GF 99. Any Deco part of the dive is shown in red colour at the top. You can clear a deco obligation during the dive and not have to end the dive. Your NDL will show again when you have done that.

 

[NothingClever]

I can’t see all replies here because I’ve learned to put some people on ‘Ignore’ for the delusional, self-centered and/or simply inaccurate assertions they make.

Just a general thought - technical diving concepts and the associated lexicon can be captivating but I’d caution us against perceiving that buying a tech computer and setting it to tech mode as recreational divers somehow makes us more advanced.

As a parallel, I can buy a top of the line motorcycle with race technology but if I don’t have race training and experience, I’m only fooling myself to think I’m a racer, the suspension technician or the data analyst and ready to start tinkering with advanced settings. Going fast on a motorcycle in a straight line down the highway and then talking with the guys at the cafe about all the available technical aids (traction control, wheelie control, ABS settings, etc) requires zero talent, just enthusiasm.

When I go to a track where I see riders can truly focus on maximizing theirs and their bike’s performance, then suddenly I realize as a street rider I don’t know what the heck I’m doing and that I need more training before I start tapping into the bike’s advanced settings for days at the track and race applications.

There’s nothing wrong with being a street rider just like there’s nothing wrong with being a recreational diver.