Info Why are tables not taught in OW classes anymore?

[dmaziuk]

IMO, this version of "deep stop" is completely reasonable in an NDL context. It's not going to add appreciably to the intermediate compartments that appear to cause issues with the full-blown deep stop regimen. It may help reduce overpressure for the fastest tissues, but IMO the greatest benefit would be in helping sloppy ascenders getting their overall ascent rates under control.

Or you could reduce the half-time of your fastest tissue compartment: either way the net result is slowing your ascent rate and there is a simpler way of doing that. It starts with "slow" and ends with "down".

 

[scubadada]

Hi @lowall

My family still has and still dives several older Oceanic computers. Pro Plus 2s and my VT3 do not include deep stop. We have a Geo 2 and a VT4 that have deep stops and are also the only Oceanic computers we have that run PZ+ in addition to DSAT. Looks like deep stop was added around 2009.

On the Geo 2 and VT4, the deep stop can be turned off or on. If on, it is activated when you go below 80 feet and then gives you a 2 min stop at 1/2 max depth. Apparently, there is no penalty for skipping it and it is disabled in deco. Nobody in the family has ever used it.

No other computers we own or owned have deep stop

EDIT: Interesting, the Geo Air, Oceanic's newest computer, still has the deep stop.

 

[steinbil]

Can you do a multi-level dive using just tables? Of course you can, just as you can do a multi-level dive with neither tables or a computer. You might be OK. You might not. The only option to doing it with any guidance is doing it with a computer.

This has been repeated again and again in this thread, and I know the PADI tables specify not to use it for multilevel dives, but is it really that black and white? I'm asking this sincerely, in good faith.

The GUE MDL tables allow for judicial depth averaging with some caveats. (only average bottom part of dive, avoid sawtooth profiles, start at the deepest point, minimum 1hr SI etc.) I have yet to see any problem with this, and when I compare the dive profiles I've had following my Perdix and diving on the tables with depth averaging, they seem very similar. If anything I would guess the tables are a tad more conservative.

Unless there are dives you could do in this way that would overstep the limits of following the computer, it's misleading to say it doesn't provide any guidance. If it in fact keeps you within the limits, it would be a safe alternative. I'm not trying to say it's as efficient as using a computer if you're trying to maximize bottom time, especially if you're riding the NDL, but if it gives you realistic and practical profiles that work and are safe I don't see the problem.

Could you provide me with an example (real or hypothetical) of a multilevel dive that would be "allowed" by depth averaging the tables but that would overstep the limits of (i.e. lead to deco in) Buhlmann with a GF hi of 85, for example? I don't even know how to do this, outside of comparing it to actual dive profiles (and I don't have any with deco incurred since I'm not trained for that).

PS.
I mostly do local dives, so I'm no expert on typical profiles of dm-guided tropical dives, but the few I've done would work with tables since they usually start at the deepest point and gradually get shallower, and they have also not been very aggressive.

 

[tursiops]

This has been repeated again and again in this thread, and I know the PADI tables specify not to use it for multilevel dives, but is it really that black and white? I'm asking this sincerely, in good faith.

The GUE MDL tables allow for judicial depth averaging with some caveats. (only average bottom part of dive, avoid sawtooth profiles, start at the deepest point, minimum 1hr SI etc.) I have yet to see any problem with this, and when I compare the dive profiles I've had following my Perdix and diving on the tables with depth averaging, they seem very similar. If anything I would guess the tables are a tad more conservative.

Unless there are dives you could do in this way that would overstep the limits of following the computer, it's misleading to say it doesn't provide any guidance. If it in fact keeps you within the limits, it would be a safe alternative. I'm not trying to say it's as efficient as using a computer if you're trying to maximize bottom time, especially if you're riding the NDL, but if it gives you realistic and practical profiles that work and are safe I don't see the problem.

Could you provide me with an example (real or hypothetical) of a multilevel dive that would be "allowed" by depth averaging the tables but that would overstep the limits of (i.e. lead to deco in) Buhlmann with a GF hi of 85, for example? I don't even know how to do this, outside of comparing it to actual dive profiles (and I don't have any with deco incurred since I'm not trained for that).

PS.
I mostly do local dives, so I'm no expert on typical profiles of dm-guided tropical dives, but the few I've done would work with tables since they usually start at the deepest point and gradually get shallower, and they have also not been very aggressive.

You've jumped from GUEs averaging the bottom depth (you are diving over a bottom with bumps between (say) 80 and 90 ft, so you call it 85 ft*) to depth averaging the entire dive, for example 90 ft is the max depth of the dive, and you do a kind of linear multi-level dive, which you now call 45 ft). THAT is quite wrong, will give the wrong assumed N2 uptake for the dive, and has been shown time and again that it is incorrect. The reason it is wrong is because depth averaging is a linear process, but the on-gassing of N2 is not. You on-gas more at depth than you would think from just simple extrapolations from shallower. You can convince yourself of this quickly with any table: look at the NDL for some depth; now look at the NDL for twice that depth; do you get half the NDL? No, not by a long shot.

I can't give you an example of a "multilevel dive that would be "allowed" by depth averaging the tables but that would overstep the limits of (i.e. lead to deco in) Buhlmann with a GF hi of 85, for example?" because there is no way to validly "depth-average" the tables. It is just flailing in the dark.

*By the way, you'd have to call this 90 ft on tables anyway, so what's the point?

 

[Rob9876]

When I started diving in the late 1950s and early 1960s, I was a poor high school student, who had a dive watch that I bought for something like $19.99 and a capillary depth gauge.
. . .
Tables, a watch and depth gauge are much less expensive than a submersible computer.

While it is a somewhat expensive hobby, dive computers are actually not that bad (at least for the basic recreational level). $20 in 1960 is approximately equivalent to $200 today, and you can often find new computers in that price range that are fine for beginners -- such as the Cressi Leonardo or the Mares Puck Pro (I've got about 150 dives on a Puck Pro).

Now if that high school student gets on ScubaBoard they'll be told they really need a Shearwater, so that is a lot more to save toward.

 

[Eric Sedletzky]

…A kid cannot afford a tank, regulator, peripherals like LP inflator hose, SPG/Computer, wet suit, and BCD. Tables, a watch and depth gauge are much less expensive than a submersible computer. Kids cannot work picking strawberries anymore, due to concerns about pesticide exposures. So how does a kid get into scuba diving?

Well, actually some new computers are cheaper than buying a new analog depth gauge and a new watch that’s good enough to trust on a dive.
You can buy a Mares Puck computer for probably $169 to $189? I’m guessing?,mine was $159 but that was several years ago. A wrist analog depth gauge will be $89 and a cheap watch with a bezel probably $90 -$150?
So if new the cheap computer is a better deal.
Also, the computer can always be used in gauge mode if wanted.
But those are new prices, used might be a different story, and this is where you make an excellent point. Gear has gotten so damn expensive and really does bar entry, unless you know the secrets about good used gear.
I am given all sorts of free gear all the time. A lot of the reg sets have consoles which normally have a pressure gauge, analog depth gauge, and sometimes a compass - typical of the day. Most all this stuff is serviceable and usable.

I’m on a kind of crusade to find good used gear and set up young people looking to get into diving. It’s my way of giving back.
I already set up my buddy and his son who has been diving for years but lost everything in one of the California wild fires.
The point is, there is a ton of great used gear out there just screaming to be used, you just have to know what you’re looking at. Most of the time this stuff does not include a computer.
That’s OK, because tables are always an option, and once you have them there are no batteries or flooding, or glitches, or dying, etc.
Tables might not be ideal and limited to square profiles, but better than nothing.

 

[Eric Sedletzky]

Now if that high school student gets on ScubaBoard they'll be told they really need a Shearwater, so that is a lot more to save toward.

They’ll be told they need way more than a shearwater!
Don’t forget about the BP/W w/hog harness, long hose, Jet fins/Eddy’s/or some other favorite paddle fin because they’ll need to back up, heli turn, stay in trim in the perfect sky diver position. They be told they need to set themselves up for the eventual set of doubles, fundies, sidemount, CCR, they’ll also need a $1500 can light and a $5000 scooter for when they finally take cave 1, 2 and 3. Throw in some names like Deep6, Hog, Scubapro is evil, etc. and anybody not diving in a drysuit is an amateur broke idiot.
This is all within the first five minutes after they introduce themselves in the “New divers- people considering diving” forum.

 

[boulderjohn]

Any idea what it will cost that kid when he makes the competitive soccer club and buys his soccer shoes, shin guards, uniform, offical team bag, and a game quality soccer ball? High quality shoes and a good ball cost way more than a basic dive computer--over $250.

If he or she wants to play football, better get the best ball--A Wilson "The Duke" at $150. Then pay for the uniform.

Priced a good pair of skis lately? When you get them, you can take your kid to a day of skiing at Vail resorts in Colorado. One day adult tickets go for about $160, but if you go for a week, you can get a 6 day ticket for $560-$800.

 

[Eric Sedletzky]

Any idea what it will cost that kid when he makes the competitive soccer club and buys his soccer shoes, shin guards, uniform, offical team bag, and a game quality soccer ball? High quality shoes and a good ball cost way more than a basic dive computer--over $250.

If he or she wants to play football, better get the best ball--A Wilson "The Duke" at $150. Then pay for the uniform.

Priced a good pair of skis lately? When you get them, you can take your kid to a day of skiing at Vail resorts in Colorado. One day adult tickets go for about $160, but if you go for a week, you can get a 6 day ticket for $560-$800.

Should we get into high end road bike bicycles or golf? What does a high end set of clubs and all the garb go for, and don’t forget about green fees at an upper end golf course?

 

[brsnow]

Scuba is my cheapest hobby. I did learn tables, but do use computers, I don’t own hog or deep6.