Faith diving and magic?

[LeadTurn_SD]

OK, now I understand. It is information you like to have with you during the dive.

Exactly the same as me wanting to know the very last moment that I can escape undrowned or unbent. I'm never planning to use that information, but plans go to pieces at times. So basically, you're saying that if your computer tells you something stupid you have something to compare "stupid" to. You compare "stupid" to a square profile that is diveable, I compare "stupid" to the worst dive that I can survive.

Two different ways of staying on course, what's the diff?

Best wishes.

Yep. Thanks lowviz, you put it more clearly than I did, I tend to fumble around while trying to express my ideas sometimes

Actually, my true feeling is not so much that the computer is likely to tell me something stupid.... I guess it is that the more I plan the dive, the less likely it is that I am going to do something stupid with what the computer is telling me!

Best wishes.

 

[lowviz]

................ I guess it is that the more I plan the dive, the less likely it is that I am going to do something stupid with what the computer is telling me!.................

You are on the right path. You computer is a piece of electronics, programmed by whoever, that serves up dive directions in a fashion that is acceptable to lawyers. Damn convenient.

Trust but verify.

 

[SailNaked]

I guess I should enter this conversation also.

So in a perfect world we would all dive from shore to places we have been before in no current. the water would be warm and the beer cold at the end of the day.

rec. divers would only dive rec profiles. we would use safety factors that were tailored to our particular physiology. we would all "plan our dive and dive our plan" because we would control all the variables in our environment.

when I dive in Bonaire we do a set of dives that are to 70ft until 1300# up current then up to 40ft back to the start and usually out of the water with 500-1000# the plan is easy because all the dives are the same and the bottom contour is the same we dive nitrox and there is really no point in taking a computer except as a dive logging device, we never hit any limits of any kind.

Coz there is not a typical dive, except that the first dive is deeper than the second. Profiles look like 130 to 80 to 60 to 40, or 80 to 60 to 40, and then we do a nice 60-40 drift sometimes at high speed. to get out of the current sometimes you drop into a hole and it can be as deep as 20ft from average dept of dive. if you happen to drop in on a sleeping shark and want to video it up close then you may stay there some time.

figure this on a table, you did a 130ft dive for 59 minutes, 1.5 hour SI, then you did an 80ft dive for 63min, 2.5h SI 80ft 65min, then a 60ft dive for 58min. (all with 5 min safety stops)

we do not have an exceptional SAC it is about .5-.4 so for us at 500# we have about 5 minutes of safety stop on one tank sharing air. on this dive we did over 20 minutes of Stop on two tanks which means we left the bottom with over 1k each. What made this unique was the high shallow loading.

So when I dive in Coz I use my computers to let me know if I am at any limits that are important like NDL, I was totally surprised to be at a Limit on that dive so late in the dive maybe I should not have been and maybe I was just having too much fun and maybe the narcolepsy fairy was visiting. I definitely learned some stuff to watch for. but I still fly my computer in places that are not table friendly.

 

[DandyDon]

So when I dive in Coz I use my computers to let me know if I am at any limits that are important like NDL, I was totally surprised to be at a Limit on that dive so late in the dive maybe I should not have been and maybe I was just having too much fun and maybe the narcolepsy fairy was visiting. I definitely learned some stuff to watch for. but I still fly my computer in places that are not table friendly.

Do you both have Nitrox cards? In my Coz experience, when you do 2 - 2 tanks trips, the first one after lunch is deeper than the one before - which is not a big deal with a 90 SI, but a Nx tank on that tank helps the day a lot. Otherwise, the most liberal Oceanic computer will often approach Ndl. My preference is to always be in the green before leaving SS, which is very challenging on air.

Whatever, when your computer says you have 2 minutes left, time to start ascending, not descending to start shooting, IMO. I don't mind 1 to 3 min of Deco, if I have plenty of back gas to work back into low yellow, but that's about all I will allow for me.

 

[Polar_diver]

I am relying on my computers a lot... I dive with 2 computers and I set them to ''bip'' me whenever I get within 10 minutes of NDL. That's when I usually begin a slow ascent.

 

[lowviz]

...........rec. divers would only dive rec profiles....................

If you exit with a letter group other than "A" you are a deco diver. Rec divers are allowed to finish their deco on the surface.

we would all "plan our dive and dive our plan" because we would control all the variables in our environment.................

-We try to dive the plan because we can't control all the variables...

................
figure this on a table, you did a 130ft dive for 59 minutes, 1.5 hour SI, then you did an 80ft dive for 63min, 2.5h SI 80ft 65min, then a 60ft dive for 58min. (all with 5 min safety stops)
.........................

I'll pass on the cheap shot that starts with "You planned a 130ft dive..."

OK, computer tells you one thing, quicky verify what is the hairiest possible dive with your RMV and backgas at this depth. If reasonably conservative, I'll go with the computer.

.................What made this unique was the high shallow loading..................

Short and deep or long and shallow, tissues load. Loading is nonlinear and hard to grasp. Verify.

................ I definitely learned some stuff to watch for...................

We all did.

...............but I still fly my computer in places that are not table friendly.

I fly my computer everywhere. I'm not saying tables are fundamentally better.


You only have so much gas to spend. It is usually pretty obvious when your computer is no longer serving you. Contingency plans and a last-ditch bailout on your wrist are nice to have at this point.


Thanks for perservering through this worthwhile thread. No small task.

fyi: I am fairly new to tech and I take decompression diving seriously.

 

[lamont]

I definitely learned some stuff to watch for. but I still fly my computer in places that are not table friendly.

If you are going to "fly your computer" then you need to ascend when you go into NDLs.

If you are going to do planned decompression diving then you need to plan those dives and dive your plan.

I know you responded previously that you're trained in decompression, and either I don't believe that, or else you took the wrong class from the wrong person.

 

[Charlie99]

...............
figure this on a table, you did a 130ft dive for 59 minutes, 1.5 hour SI, then you did an 80ft dive for 63min, 2.5h SI 80ft 65min, then a 60ft dive for 58min. (all with 5 min safety stops)

OK, computer tells you one thing, quicky verify what is the hairiest possible dive with your RMV and backgas at this depth. If reasonably conservative, I'll go with the computer.

Please explain or expound on this method of planning.

 

[Rick Murchison]

...Coz there is not a typical dive, except that the first dive is deeper than the second. Profiles look like 130 to 80 to 60 to 40, or 80 to 60 to 40, and then we do a nice 60-40 drift sometimes at high speed. to get out of the current sometimes you drop into a hole and it can be as deep as 20ft from average dept of dive. if you happen to drop in on a sleeping shark and want to video it up close then you may stay there some time...

So, if I'm reading this right, when you dive Coz your dive plan is to jump in with sort of a general idea of the depth you'll dive, but with no absolute max depth decided, follow the divemaster, let interesting stuff determine the details & use the computer to monitor your deco status. You base your minimum ascent gas on what it takes to get you safely to the surface from the depth you're at rather than what it would take to get you and your buddy safely to the surface should your buddy suffer an uncontrolled freeflow or other gas failure at the end of the dive, and you have no set minimum pressure decided before you jump in. You let the computer and your remaining gas determine your bottom time rather than having any specific max bottom time set before jumping in.
I think this is pretty typical of what I see in Coz, so y'all are adhering to "generally accepted practices" there, but if I'm wrong about any of this in your case please fill me in.
FWIW, while Coz is about as flexible and casual as diving gets, The Lovely Young Kat & I still set max depth, max time and min gas (min ascent gas = gas for both of us to reach the surface with safety stop, or gas for each of us + 500psi, whichever is greater) based on the site before we jump. It isn't that hard... site descriptions including depths are widely available if you're a newbie there. Kat & I use our logbooks. Navigation we leave pretty much to the DM & the current
Under any circumstances, we set those limits specifically to avoid the kind of situation y'all got into, and I highly recommend the practice as minimum planning for Coz.
Rick

 

[lowviz]

Please explain or expound on this method of planning.

Originally Posted by lowviz

Originally Posted by SailNaked
...............
figure this on a table, you did a 130ft dive for 59 minutes, 1.5 hour SI, then you did an 80ft dive for 63min, 2.5h SI 80ft 65min, then a 60ft dive for 58min. (all with 5 min safety stops)

OK, computer tells you one thing, quicky verify what is the hairiest possible dive with your RMV and backgas at this depth. If reasonably conservative, I'll go with the computer.

Jeez, I did post that. Yeah, pretty bad with my cut/paste while assembling the answer.

OK, computer tells you one thing in dive plan mode, test against table of your choice and if reasonably conservative, I'll go with the computer as working properly.

Then quickly verify what is the hairiest possible dive with your RMV and backgas at this depth. (is it even possible to perform this dive with my backgas? -that info is on my slate) Instant sanity check. So now, computer is working and I have an idea of how long I alone can stay down, make a dive plan and test it against "thirds" or "halves plus Rock Bottom".


-I didn't see any problem with applying tables to those three dives, so I presume the question was how to check on the computer before the first and each subsequent dive.