Is my approach to diving with Nitrox logical?

[Nitrox_DiverNY]

I use several ops but prefer JDC. That dive was with JDC, yes, 45m bottom, everyone up at 55m, min 500 psi back on deck, no deco. Okay, so I stretch the rules a little that day, spear me!

Yes, I am using the Peregrine, set at the High setting and yes using the surface GF to guide my surface interval time. After this dive I reset my computer to the Medium setting. There is High, Medium, Low conservatism and Custom. I need to get another Shearwater so both of my computers can be configured the same though I like that Scubapro hose end Matrix, I wonder if it can be adjusted to run similar to the Shearwater computers. I have my current second computer set to try and match my Shearwater but it never went into deco on that dive so obviously this is a problem with two computers not of the same make or algorithm. I reset as I said the Shearwater to Medium and now the two computers seem to mimic each other well enough. I need to follow my own advice and get matching (similar settings and algorithm) computers! But I just got new computers for my wife and now a new engine for my Toyota so I am once again poor ;(.

James

how do you like the Peregrine? It looks like a really nice computer and seems like its very customizable. Was thinking of eventually getting one, what algorithm does it run? is this a good computer for more conservative practice? thanks

 

[Eric802]

The Peregrine runs the Bühlmann ZHL-C and it’s highly customizable. I think there are 3 preset conservatism levels you can select, and you can set your own as well. Also has a very easy to read screen and it’s easy to use. Love mine.

 

[Nemrod]

how do you like the Peregrine? It looks like a really nice computer and seems like its very customizable. Was thinking of eventually getting one, what algorithm does it run? is this a good computer for more conservative practice? thanks

I love the Peregrine. I would describe it as light technical. It can handle deco and three gas Nitrox. As mentioned it is highly customizable, feature rich and the menus are intuitive and easy to use. The screen is bright and easy to read. Cons, the battery is not user replaeable, there is not a compass. Pro, it is not AI (which is a pro for me) and the size, features and capabilities are hard to equal at the price range. I would highly recommend the computer, the supplied silicone strap not so much since mine broke the first dive. Shearwater does supply a bungee and now that is how I affix mine. Yes, they sent a new strap that looks like the strap that broke first use so I do not trust that. I am not sure there is anything better for this price and niche.

Yes there are three preset levels and you can set a custom level if desired. The Shearwater cloud seems to work easy, the software update I just did went painlessly. Yeah, I recommend it for what that is worth.

AI, uh, just no. I like my spg just fine thank you and my traditional compass when it comes down to it.

James

 

[Jcp2]

It's a good idea to know how much gas you need to make a normal ascent. If you know your average RMV, it is very easy to make the calculation.

As an example, to ascend from 90 feet and make a 3 min SS, I need about 165 psi from an AL80. For a 5 min SS that increases to a little over 200 psi.

For a dive with the profile that @Nemrod posted above, the operator recommends leaving the bottom at 800-1000 psi, that would work out fine for most divers and allow them to surface with the requested 500 psi or more. I did 9 dives on the Jupiter reefs during my recent visit and dived with AL80s with around 36% nitrox. My average surfacing pressure was just under 1100 psi (916-1334). My average surfacing GF was 63 (57-71).

You can learn a tremendous amount by paying attention to your previous dives. It helps you avoid being surprised.

I’ve got quite a ways to go then. I surface with 1200 with HP100 on PVD 60 minute 50 feet reef dives. Not quite ready for Jupiter then.

 

[BoltSnap]

I am not sure there is anything better for this price and niche.

Yes, there most definitely is:

iX3M 2 | Dive Computer

There are three (3) models to chose from, you can start with the basic model (the Pro model), and then pay a license fee to upgrade its firmware to the higher model without having to buy a whole new computer. It the "basic" model, PRO, has all of the possible features a recreational diver at all levels needs or wants.

 

[Nemrod]

Yes, there most definitely is:

iX3M 2 | Dive Computer

There are three (3) models to chose from, you can start with the basic model (the Pro model), and then pay a license fee to upgrade its firmware to the higher model without having to buy a whole new computer. It the "basic" model, PRO, has all of the possible features a recreational diver at all levels needs or wants.

Those are fine computers though in NA not sure they are available whereas Shearwater is made in Canada and appears to be much smaller, more compact and less money by quite a bit. Deep Six has an interesting computer and Scubapro, well, they are the Pros, hard to go wrong with that magic S on your gear. I will stay with my recommendation as being solid for the price and features and form factor.

For me, I am not interested in anything AI unless it is optional and the screen and features are not compromised with unused space for data I do not want. I look at my spg at the beginning of the dive and to make sure it does not fall when I breath, I look at it again about midway or turn point. I look again at ascent time and then if the DM wants to see the deck pressure yet again. That is it, I do not want my space or mind cluttered with psi, air consumed, average rate of consumption or any of that data which means nothing to me (and I am saying me as in myself). I dive to see things and enjoy the experience, not crunch meaningless to me numbers. My spg is all that I need.

James

 

[scubadada]

I’ve got quite a ways to go then. I surface with 1200 with HP100 on PVD 60 minute 50 feet reef dives. Not quite ready for Jupiter then.

I would imagine you would do fine in Jupiter. Steel 100s are commonly available. At least with JDC, your bottom time is 45 min, keeps almost everyone out of deco and with plenty of gas. For the 9 dives I mentioned above, my avg depth was 62 ft (59-66). If you know your RMV, you could calculate the gas needed for these dives.

So, for a 53 min dive time at an avg depth of 62 ft at a RMV of 0.5 cu ft/min (near average Average Gas Consumption) you would need 76 cu ft of gas. An AL80 would be insufficient but a HP100 would give you a hefty reserve.

 

[Blackcrusader]

thanks for sharing but I have to admit I am lost with the graph lol. Might need another cup of coffee to understand this. What is the difference between GFlo and GFHi? so if they are both set to 100% then its very liberal correct since its Bulhman?

RGBM does not have a GF factor correct?

and yes as others have said here to adding in longer stop, not pushing NDL, etc all adds and I agree

RGBM does not have GF factor. GFlo is the setting for Deco dives so you can ignore that if you are not doing deco dives. GFhi is for your NDL diving. By the way I am diving with 2 other divers soon for near 3 weeks. I have to be careful that other divers do not simply follow me as my DC is using Bulhman and my GFhi is set at 95. One of the divers I have never met and I do not know what DC he has.
I have had divers not pay attention to their own DC's running RGBM and had them show deco obligation because they did not pay
attention to their NDL settings.

Right now you are overthinking about DCS. Not a bad thing to consider but at shallow depths very unlikely you would ever get bent on NDL dives. My own DC is set for 5 minute safety stops not 3 minutes. It also shows the number of minutes past your safety stop as well.
SO you can see from this log the GF is set at 45 GFlo/95 GFhi. Where I have taken this screen shot is at 27 minutes 30 seconds into the dive. As you can see I still have 4 minutes NDL which is more or less about the time I like to have to no exceed NDL. So on this dive I was staying deep but coming up slowly just to keep the NDL around 4 minutes. So some would say this is pushing the NDL as I only ascend to avoid going into deco. Very shallow at the end for off gassing. A point to note is that a safety stop is not mandatory but recommended.

A Shearwater Peregrine would be a good DC to consider. I am using a Shearwater Perdix but no AI but does have internal digital compass. As one member wrote it is good to get to know your dives and your understanding of your gas usage. I do not gas plan NDL dives as a matter of habit but I do in my head go I will do this dive and expect to end the dive with a certain pressure left in the tank.
Uploading your dive logs and reviewing them can be good fun.

 

[Nemrod]

I’ve got quite a ways to go then. I surface with 1200 with HP100 on PVD 60 minute 50 feet reef dives. Not quite ready for Jupiter then.

You would not have a problem. You do not have to stay with the DM. You can surface at any time your air or NDL or your comfort zone demands. Just have a safety sausage and know how to shoot it. I send mine up at 30 feet when I do my (shhhh) 30 foot or half depth pause. The captain will come and get you. JDC does have 100 cf tanks and they are good about not leaving divers out to sea! Since you are riding the same current you will be surprised to find other divers popping up around you. Sometimes a nice bull shark will hang out with you when you are all alone to keep you company, nice fellas they are being so kind.

N

 

[kelemvor]

NAUI?

I can only say as far back as 2012 when I first got certified, at that time NAUI was using 1.4ppO₂.