Average depth finder

[tbone1004]

It is a part of a dozen or so experimental / test dives I plan on doing this winter. Testing a few profiles generated by conventional US navy tables against depth averaging tables against Buhlmann with gradient factors.

This is not how I would usually dive

why not just get a dive planning software to check against buhlmann, and then run the same dive plans against the USN tables and whatever depth averaging abomination UTD is trying to teach these days? Remember than the USN tables are VERY aggressive by comparison to most dive computers and they also go by "bend them and mend them" with a rather disturbing number of acceptable dcs hits if you don't remember that they have a chamber on board all dive vessels so the maximum time they'll be 'bent' without treatment is maybe an hour?

 

[CAPTAIN SINBAD]

Are you using UTD's NDL/Min Deco Table?
Depth : NoStop Time
40'/12m 170min
50'/15m 60min
60'/18m 50min
70'/21m 35min
80'/24m 30min
90'/27m 25min
100'/30m 20min
110'/33m 15min
120'/36m 10min
130'/39m 5min

The NDL/NoStop Times above for Air are similar to the conservative HUGI Table 1.
Written in my wetnotes & memorized, along with the UW 330m BT as back-up to my dive computer (Petrel2).

The one I have is a Nitrox table.

 

[CAPTAIN SINBAD]

why not just get a dive planning software to check against buhlmann, and then run the same dive plans against the USN tables and whatever depth averaging abomination UTD is trying to teach these days? Remember than the USN tables are VERY aggressive by comparison to most dive computers and they also go by "bend them and mend them" with a rather disturbing number of acceptable dcs hits if you don't remember that they have a chamber on board all dive vessels so the maximum time they'll be 'bent' without treatment is maybe an hour?

Yes I have been comparing profiles on multi-deco for a while now. Instead of running hypothetical scenarios on Multideco, I would like to do a few dives with it.

 

[stuartv]

My H3 shows AVG during the dive. My Perdix that should be arriving this week will also show it. You can borrow either, any time.

 

[stuartv]

You are gonna use (trust) a computer to calculate a weighted average for your depth and then take this information and do mental math to calculate your ascent protocol... why.. because computers and electronics and their associated calculations are not to be trusted? LOL It just seems so bizarre to me.

Exactly.

Perfect example:

Written in my wetnotes & memorized, along with the UW 330m BT as back-up to my dive computer (Petrel2).

Depend on an electronic device to calculate your average depth, then depend on wetnotes, memory, and/or mental math to calculate an ascent, instead of just spending the same money (as a UW 330) to buy a backup electronic device that can actually calculate an ascent for you.

At least, if you wet your fingers and touch contacts A and B on the UW 330 before you start your dive, it will tell you if it has a low battery ... as long as you remember to wait for it to finish its self-test and then watch for it, because it only displays the low battery indicator for 10 seconds. If you forget to turn it on and check before the dive, it will still tell you - just after you get in and it automatically turns on. I'm sure you'll be waiting and watching for that indicator right after you jump in, right?

Makes perfect sense.

 

[Kevrumbo]

. . .At least, if you wet your fingers and touch contacts A and B on the UW 330 before you start your dive, it will tell you if it has a low battery ... as long as you remember to wait for it to finish its self-test and then watch for it, because it only displays the low battery indicator for 10 seconds. If you forget to turn it on and check before the dive, it will still tell you - just after you get in and it automatically turns on. I'm sure you'll be waiting and watching for that indicator right after you jump in, right?

Makes perfect sense.

Sure, waiting & watching for that indicator about as long as you checking your AI transmitter for basic functionality. . .

 

[CAPTAIN SINBAD]

I knew this would turn into a Ratio Deco thread sooner or later

 

[stuartv]

Sure, waiting & watching for that indicator about as long as you checking your AI transmitter for basic functionality. . .

I always check my SPG before I get in. No waiting or anything different to my process because it's AI. And if my computer or transmitter battery gets low, it will display an indicator that stays on. No concern of not looking during one 10 second window and missing it.

 

[Kevrumbo]

I knew this would turn into a Ratio Deco thread sooner or later

What about the UTD Table are you planning to test? NDL/NoStop or light deco on backgas or Oxygen?

 

[boulderjohn]

When I was with UTD, I used a Uwatec bottom time and used its average depth feature for those calculations. Near the end of my UTD experience, though, Andrew said that was not the right thing to do, because he said the time descending should not be included in that average. You were supposed to start averaging once you had reached your bottom depth. This was to be done by checking your depth every 5 minutes and maintaining a running average of those 5 minute checks in your head. That was considered to be a far better system than using a computer for calculations, because unlike the human mind, computers are capable of making mathematical errors. I don't know if they are still advocating that system for averaging.

It is a good idea to carry a computer in gauge mode, whether it shows you the average depth or not, so you can later compare what the computer thinks you did on your dive with what you think you did on the dive. You should have seen the case of two friends of mine. The graph of the dive shows them hitting their planned bottom depth and then drifting slowly downward until they did their first 5 minute check and returning to their planned depth. Then they would drift down, check their depth, and go back up. They did that throughout the dive. They later decided that the computer thought they were on average about 8 feet deeper than their calculations. Who knows which was right? (They were, of course, looking at the log to try to figure out why they got bent.)