Bottom Timer/Wrist Computer Question

[ucfdiver]

Do you have any GUE or UTD training? If so, how to use average depth to generate RD profiles should have been covered. It's limitations and relevant work arounds would have also been covered. Your discussion of pure Buhlmann profiles in this forum is rather frightening as well...

No, I don't. However, I would challenge you to find a GUE trained Cave 2 diver who actually uses ratio deco in NFL caves (the situation described). Having done about 80% of my diving with C2 divers over the past year, I've yet to see one suggest ratio deco, 2 of the ones I've dove with are on the WKPP and they're certainly not using it for bottom times in the range of what we see in NFL, Ginnie or Wakulla. They do reshape the curve, but the starting point is typically Bühlmann or VPM tables. For OW, some of them use it, but it's clearly not being taught to all C2/T1 students as the primary means of dive planning.

And what's wrong with discussion of pure Bühlmann in the context of which I did? The gradient factors don't come into play until you start your ascent...after all, a 20/85 gradient factor is simply saying that you'll start your slow ascent at 20% of the range between M value and the ambient pressure, and from there you'll keep the ascent slow enough so that you stay at or below 85% of that difference by the time you surface.

So let me ask you, what good is having a computer that does average depth for you, when average depth isn't what you're really using?

 

[Rainer]

RD is not covered in Fundies. Some instructor might add it to the course, but it isn't required material.

We certainly had a discussion in Fundies about how to use average depth (as opposed to max depth) with NDL/MDL tables for recreational (min deco) dives. Obviously a discussion is needed about when the actual average can be used and when you need to weight that average shallower/deeper. A similar discussion is had about RD profiles. This is all pretty standard DIR stuff.

 

[Rainer]

For OW, some of them use it, but it's clearly not being taught to all C2/T1 students as the primary means of dive planning.

LOL, and I don't know any DIR divers (having lived on both coasts, that's a fair number) that don't use average depth (properly weighted, of course, depending on profile) in planning their recreational or technical dives. Granted, this is OW stuff, but that covers both square and multi-level profiles.

Knowing how to use average depth is really a pretty core skill of DIR diving.

So let me ask you, what good is having a computer that does average depth for you, when average depth isn't what you're really using?

I've already posted that I don't see the point of this feature. But if you have a computer with a resettable average (e.g. Tec2g, not the new Uwatec), then at least you *could* make some of use of it. The point is, this is info you ought to be tracking yourself.

Or feel free to simply do all your deco based on max depth. It's certainly conservative.

 

[ucfdiver]

LOL, and I don't know any DIR divers (having lived on both coasts, that's a fair number) that don't use average depth (properly weighted, of course, depending on profile) in planning their recreational or technical dives. Granted, this is OW stuff, but that covers both square and multi-level profiles.

Knowing how to use average depth is really a pretty core skill of DIR diving.



I've already posted that I don't see the point of this feature. But if you have a computer with a resettable average (e.g. Tec2g, not the new Uwatec), then at least you *could* make some of use of it. The point is, this is info you ought to be tracking yourself.

Or feel free to simply do all your deco based on max depth. It's certainly conservative.

Where are you getting that I don't use average depth? My very first post gave an example of where I DIDN'T use max depth, and didn't use absolute average as one of the uwatech's would display, either.

My issue is ...let's say you do a wall dive, 100ft for 15 minutes and then come back up to the 40ft ledge for 15 minutes. That's 30min @ 70ft for avg depth, which both of us know better. Exaggerate this profile to fit a deco dive and compare the profiles...So now we're back to having features on computers that simply take up screen space and aren't useful.

That's all I was saying.

 

[LiteHedded]

LOL, and I don't know any DIR divers (having lived on both coasts, that's a fair number) that don't use average depth (properly weighted, of course, depending on profile) in planning their recreational or technical dives. Granted, this is OW stuff, but that covers both square and multi-level profiles.

avg depth yes. ratio deco no

 

[Rainer]

And was RD not at least taught in your GUE/UTD classes?

avg depth yes. ratio deco no

 

[Rainer]

My issue is ...let's say you do a wall dive, 100ft for 15 minutes and then come back up to the 40ft ledge for 15 minutes. That's 30min @ 70ft for avg depth, which both of us know better.

What exactly is your issue with the above average?

So now we're back to having features on computers that simply take up screen space and aren't useful.

That's all I was saying.

Post 12.

 

[Blackwood]

No, I don't. However, I would challenge you to find a GUE trained Cave 2 diver who actually uses ratio deco in NFL caves (the situation described).

The few GUE C2 divers I know use Ratio Deco on average depth. Not in NFL caves (they're Mexico peeps), but I'm not sure how that matters much.

Use what you're comfortable with.

So now we're back to having features on computers that simply take up screen space and aren't useful.

It doesn't take up much screen space. It's actually pretty hard to read at times because it's so small and usually has to be toggled (mine likes to show temperature down there).

If you like, you can re-set the average depth at an appropriate point. When we dive, we generally start computing average depth on the bottom since it's mentally easier and it's more conservative. With a few button clicks, you can start the average running from the bottom on the 2G.

I sometimes do it (if I'm thinking about it) because it's fun to see how close I can get to what it reads (i.e. 1' precision rather than 10'), but we run our deco off the mental math.

 

[liuk3]

No, I don't. However, I would challenge you to find a GUE trained Cave 2 diver who actually uses ratio deco in NFL caves (the situation described). Having done about 80% of my diving with C2 divers over the past year, I've yet to see one suggest ratio deco, 2 of the ones I've dove with are on the WKPP and they're certainly not using it for bottom times in the range of what we see in NFL, Ginnie or Wakulla. They do reshape the curve, but the starting point is typically Bühlmann or VPM tables. For OW, some of them use it, but it's clearly not being taught to all C2/T1 students as the primary means of dive planning.

Are you saying that you know GUE T1 divers who were not taught ratio deco?

Now whether people want to use it after being taught it is a personal choice. Each person has to make their own personal decisions in how they want to dive and take personal responsibility for their diving. I have to respect your right to do so.

 

[LiteHedded]

And was RD not at least taught in your GUE/UTD classes?

all i've taken is fundamentals. and it wasn't covered.
it was covered in friends' courses. but not as a primary planning tool

My issue is ...let's say you do a wall dive, 100ft for 15 minutes and then come back up to the 40ft ledge for 15 minutes. That's 30min @ 70ft for avg depth, which both of us know better.

I'd be cool with that.