Bottom Timer/Wrist Computer Question

[AndyNZ]

Is there a wrist computer (non trimix) other than the Tec2G which has the average depth function?

The VR3 does, which comes in a OC nitrox version as well as trimix.

It has no gauge mode, though. I've got one for sale if you are interested.... and that should probably tell you what you need to know!!!

 

[Rainer]

Is there a wrist computer (non trimix) other than the Tec2G which has the average depth function?

I really don't get the desire for this feature. If you're not comfortable enough running an average depth on your own, why dive in gauge mode at all? Might as well just have the computer function as an actual computer and give you NDL info. You clearly don't trust yourself to track your decompression obligation anyway.

For practice purposes, having the computer give you an average depth on download (as most do) is good enough.

 

[Scott L]

I really don't get the desire for this feature. If you're not comfortable enough running an average depth on your own, why dive in gauge mode at all? Might as well just have the computer function as an actual computer and give you NDL info. You clearly don't trust yourself to track your decompression obligation anyway.

For practice purposes, having the computer give you an average depth on download (as most do) is good enough.

I hear you. I have heard chatter from a DIR instructor that the Tec2G average depth function will be good for Tech 1 class although several other instructors utilize Suuntos. Just wading through the conflicting information that is sometimes heard...

 

[lamont]

My Vyper has been working since 2004. Been through a few other computers, but the Vyper has been rock solid reliable over the years.

 

[Guy Alcala]

Is there a wrist computer (non trimix) other than the Tec2G which has the average depth function?

Any of the Galileos. A used Terra would probably be cheapest, but a Luna without the transmitter would be next, if you can find one in the US. I'm trying to convince LP to offer them that way, as that spanish etailer (forget the name) does. No DSS boot, but some of the biggest fonts around, and the best laid out display IMO.

Guy

 

[Scott L]

Any of the Galileos. A used Terra would probably be cheapest, but a Luna without the transmitter would be next, if you can find one in the US. I'm trying to convince LP to offer them that way, as that spanish etailer (forget the name) does. No DSS boot, but some of the biggest fonts around, and the best laid out display IMO.

Guy

You may be referring to this site that does not appear to handle Scubapro any longer. I guess SP and AL have caved under the pressure from brick & mortar operators...

Scubastore. Online dive gear and dive equipment shop.

 

[Scott L]

I believe I have enough information to work with now. Thanks guys! Will leave open for others to expand on...

 

[ucfdiver]

Correct me if I'm wrong, but isn't using the average depth function a not so good way to calculate deco...or at best good for nothing more than a reality check?

I know with Bühlmann, to calculate tissue pressure, you start with the initial pressure, and add that to the difference between the theoretical pressure in your body and the pressure of your breathing mix multiplied by a value derived from a table (which basically just determines how fast the specific tissue absorbs whatever inert gas is in the breathing mix). I'm not very well educated on VPM aside from the basic "bubbles always exist" knowledge (IE I can't calculate it without deco software), so I'm not 100% sure how that is calculated. Either way, on a multi level dive, Bühlmann models short deeper portions as being significantly faster tissue loading than the rest of the dive.

I've seen an UWatech be as much as 20ft off in depth because the diver was swimming up a spring run to get into the cave, doing predive drills before the dive really started, and then had to wait at the entrance for an exiting team. While this was the true average depth for his profile, tissue loading is not linear, and I'm not so sure that these average depth features couldn't give a false sense of security when the diver skimps on deco.

This weekend we were diving Little River. The team ahead of us decided to run a line as sloppy as possible, making it difficult to keep ours out of their way on exit. Because of this, entry took about 10 minutes to gold line, time which was all spent >40ft deep. Within 5 minutes after that, we were at 90-100ft the rest of our 60 minute dive. I'm guessing the computer would have seen this in the 75-80ft range, but mine is an older model that doesn't do average, so I'm not real sure. I counted it as 90, since the majority of time was spent at 90, with equal portions being spent at 40 and 100ft depths...10-15ft isn't huge, but I'm guessing with the right profile, it could be serious?

I guess we're talking small margin of errors under normal circumstances, but I thought one of the reason DIR didn't like computers was that it allowed you to be lazy? I'd almost rather use a computer than a bottom timer that calculates avg depth, since the computer knows how tissue loading is effected by depth changes...if it weren't for the fact that it limits how much you can shape your deco and also didn't have the issues of profiles not matching your buddies.

Maybe I'm over-thinking this...for profiles like this, I've experimented with longer deco, slightly shorter deco, staying deep longer, following pure Bühlmann with various GFs (get shallow faster) etc, and the only correlation I can find between how I feel post dive is hydration and amount of sleep I got the night before.

 

[Rainer]

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...

Correct me if I'm wrong, but isn't using the average depth function a not so good way to calculate deco...or at best good for nothing more than a reality check?

I know with Bühlmann, to calculate tissue pressure, you start with the initial pressure, and add that to the difference between the theoretical pressure in your body and the pressure of your breathing mix multiplied by a value derived from a table (which basically just determines how fast the specific tissue absorbs whatever inert gas is in the breathing mix). I'm not very well educated on VPM aside from the basic "bubbles always exist" knowledge (IE I can't calculate it without deco software), so I'm not 100% sure how that is calculated. Either way, on a multi level dive, Bühlmann models short deeper portions as being significantly faster tissue loading than the rest of the dive.

I've seen an UWatech be as much as 20ft off in depth because the diver was swimming up a spring run to get into the cave, doing predive drills before the dive really started, and then had to wait at the entrance for an exiting team. While this was the true average depth for his profile, tissue loading is not linear, and I'm not so sure that these average depth features couldn't give a false sense of security when the diver skimps on deco.

This weekend we were diving Little River. The team ahead of us decided to run a line as sloppy as possible, making it difficult to keep ours out of their way on exit. Because of this, entry took about 10 minutes to gold line, time which was all spent >40ft deep. Within 5 minutes after that, we were at 90-100ft the rest of our 60 minute dive. I'm guessing the computer would have seen this in the 75-80ft range, but mine is an older model that doesn't do average, so I'm not real sure. I counted it as 90, since the majority of time was spent at 90, with equal portions being spent at 40 and 100ft depths...10-15ft isn't huge, but I'm guessing with the right profile, it could be serious?

I guess we're talking small margin of errors under normal circumstances, but I thought one of the reason DIR didn't like computers was that it allowed you to be lazy? I'd almost rather use a computer than a bottom timer that calculates avg depth, since the computer knows how tissue loading is effected by depth changes...if it weren't for the fact that it limits how much you can shape your deco and also didn't have the issues of profiles not matching your buddies.

Maybe I'm over-thinking this...for profiles like this, I've experimented with longer deco, slightly shorter deco, staying deep longer, following pure Bühlmann with various GFs (get shallow faster) etc, and the only correlation I can find between how I feel post dive is hydration and amount of sleep I got the night before.

 

[b1gcountry]

I've seen an UWatech be as much as 20ft off in depth because the diver was swimming up a spring run to get into the cave, doing predive drills before the dive really started, and then had to wait at the entrance for an exiting team. While this was the true average depth for his profile, tissue loading is not linear, and I'm not so sure that these average depth features couldn't give a false sense of security when the diver skimps on deco.

I wouldn't call the Uwatec 'off' for calculating the true average depth from the time you descend, but I get your point...

The average depth feature doesn't mean you can just turn off your brain. You still need to know how your profile was shaped, and you need to limit the amount of depth averaging you are actually doing on a true multi-level dive.

Do you have any GUE or UTD training? If so, how to use average depth to generate RD profiles should have been covered.

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

Tom