Question Took my first deco, help me to understand my computer behavior

[tmassey]

Every dive is a deco dive!

I know you’re making a joke, and that that statement does have a significant amount of truth to it, but that was something that was definitely a change of mindset when I switched to my Shearwater.

Previous to my Shearwater I had an Oceanic computer, which are pretty well regarded as the most aggressive recreational computers out there, giving the most NDL time. And so, I never went into deco with my Oceanic. And staying out of deco was a very big concern as a recreational diver.

I ended up buying a Shearwater just after I finished my decompression class. So, I now had the training to go into deco and it was a little less scary. But also interestingly, my Shearwater gave me much less time than my Oceanic would. So by switching to the Shearwater, I really did live that statement: all of a sudden, I was flirting with or actually going into deco on almost all of my dives, ones that were nowhere near deco on my old Oceanic. It really was a different mindset.

To give you an example of how much more aggressive the Oceanic could be: I have done oxygen-assisted decompression dives using my Shearwater where I literally did not violate my Oceanic, while it was merely set to air. (My Shearwater is set to 40/85.) Of course, you don’t have to use all that aggression: don’t dive near the NDL and it won’t be a problem. My philosophy was that I didn’t want a computer to limit me unnecessarily: I could manage that for myself; but if I needed the extra capability, I wanted a computer that could handle it.

Of course, after I finished decompression procedures and upgraded to the Shearwater, the line between a non-decompression and a decompression dive really wasn’t much of a line anymore. I find it a much more relaxing way to dive, not having undo stress about some scary line or number on my computer. It’s better to be able to manage it appropriately.

So, no real point to any of this nonsense story I’m telling. Other than, yes: all dives are decompression dives, just some don’t necessarily require extensive pauses on the way up. And also, taking decompression training even when a diver is reasonably content with recreational limits is not a bad thing: having that level of knowledge and capability can certainly make you much more relaxed when you’re nearing the non-decompression limit.

 

[ScubaSamScubaStevesFather]

To give you an example of how much more aggressive the Oceanic could be: I have done oxygen-assisted decompression dives using my Shearwater where I literally did not violate my Oceanic, while it was merely set to air. (My Shearwater is set to 40/85.)

That’s wild. Mind sharing the dive details of that day?

 

[BoltSnap]

That’s wild. Mind sharing the dive details of that day?

Did you get the information I sent you?

 

[tmassey]

That’s wild. Mind sharing the dive details of that day?

Sure.

I went and dug into my logs. Turns out I usually *had* bothered to set the Oceanic to the same Nitrox gas as the Shearwater. In most cases, the Oceanic simply never went into deco and the Shearwater did, so of course it didn’t get bent. Like I said earlier, when I started diving the Shearwater, it really did become ‘every dive is a deco dive’. Even when my Shearwater might give me 10 minutes of deco, my Oceanic was still in NDL.

A couple of times it did go into deco barely, and cleared before the Shearwater — even when the Shearwater knew I was on 50% and the Oceanic didn’t. Here’s such a profile: 120’ for 30 minutes on EAN27. (No, I don’t know why the goofy gas.). Switched to 50% for like 10 minutes. The Oceanic is set to 27 the whole time. Yet it had less deco and cleared faster even without the EAN50 switch.

Here’s the Shearwater:

And here’s the Oceanic:

Here’s the first time I ever bent my Oceanic. It’s on a light trimix dive with 50% deco gas. I set my Oceanic to an EAN mix with a deco curve comparable to the Trimix, and again no gas switch. I just *barely* missed clearing it.

Shearwater:

Oceanic:

Since then, I’ve both stopped downloading that computer and just leave it in air mode. I really need another Perdix, but it’s fine as a backup timer.

But yeah, I’ve never seen a computer more aggressive than an Oceanic. I vaguely remember the Oceanic described as being similar to 90/95 or something.

But once you have the training, deco isn’t really anything to avoid, so who cares? I just keep my computer at the default: 40/85.

You know what’s funny? When I first got my Shearwater, I had people telling me how aggressive I was for using 40/85 and I was going to hurt myself — I needed to be using 30/70 or less! 5 years later I had people telling me how stupidly ‘deep’ my settings were and I was going to hurt myself — I needed to be using 50/90! So far, 40/85 has worked just fine: a couple minutes of mostly shallow deco hasn’t hurt…