"Riding your Computer Up" vs. "Lite Deco"

[Basking Ridge Diver]

A minute at half max depth,

Interesting - folks on this side seem to think a deep stop is a bad thing...

 

[rivers]

Thanks. And, pardon my ignorance again, what is a 5,4,3,2,1 ascent? All I can think is 5 minutes at 6m, 4 minutes at 5m, 3 minutes at 4m, etc.. Which means 15 minutes for the last 6 meters. Which seems like a lot of time after only doing 30:00 at 30m (plus all those other stops during the ascent). So, I'm thinking it means something different. 1 minute at 6, 1 at 5, 1 at 4, etc..? I.e. a 1m/min ascent from 6m?

minute at 5, minute at 4, minute at 3, minute at 2, minute at 1. But like I said, that's us mucking about on the way to the surface.

 

[rivers]

So for those that said a bottom timer - is it fair to say you are structured and have thought out your dive plan? In other words you are not just going for a bimble below 60 feet without a plan or an idea of how deep and how long you will be staying -using a watch - bottom timer - computer or some aid in helping you determine your stay at a specific depth below 60 feet.
I should have been a bit more specific.

My general dive plan for a sea dive to 30m is: Jump in, swim around for anywhere from 30-45 minutes (conditions on the bottom determine the length of the dive), and come back up again. Ascent schedule depends on bottom time, so min deco to 15 minutes at 6m

 

[MXGratefulDiver]

Interesting - folks on this side seem to think a deep stop is a bad thing...

... some folks ... others seem to think it depends on the profile ... for most recreational profiles, I don't really see how it can be a bad thing ...

... Bob (Grateful Diver)

 

[rivers]

Interesting - folks on this side seem to think a deep stop is a bad thing...

I wouldn't say 15m is a "deep stop".

 

[Basking Ridge Diver]

It was your statement of "half max depth" - that is what is called a "deep stop" - my computer can initiate a deep stop after 80 feet if I chose to turn it on. There is no penalty for skipping a deep stop.

 

[Basking Ridge Diver]

... some folks ... others seem to think it depends on the profile ... for most recreational profiles, I don't really see how it can be a bad thing ...
... Bob (Grateful Diver)

I have read all your articles.
NWGratefulDiver.com

 

[RainPilot]

Just to add on to @rivers post, the one minute at each 3m increment above half depth INCLUDES travel time. The idea is to end up with a 3m / minute steady ascent rate from half depth. If your ascent control is good, you would not stop after leaving 15m in his example. That means you would take 7 min to ascend from 30m, a normal rec profile would be what, 2 min from 30m to 5m and then 3 min safety stop? Pretty close but i prefer the slower ascent.

And I also like to do stepped ascents in the last 6m, great practice for holding stops. Sometimes we will try do 1/2 m steps but that gets super finicky.

 

[scubadada]

You lot should read http://www.dtic.mil/get-tr-doc/pdf?AD=ADA561928 and then see how much you trust all these tables, and especially trust any conclusion reached by looking at tables in the raw.

The main plot line is fudging the parameters to the new algorithm to give appropriate (aka circa 1957) no stop times but with a hope of having a computer match the profile.

Thanks for the report Ken, interesting reading. I don't find the implementation of VVal-79 as the basis for the Navy dive computers and the 2016 Navy tables so wacky

VVal-18M generated longer NDLs than USN57 and resulted in unacceptable episodes of CNS DCS at deeper depths (130-190 feet). The target for VVal-79 were the smoothed USN57 NDLs for dives >60 fsw with a 75 fsw/min descent, a 30 fsw /min ascent, with instantaneous ascent to the surface allowed. VVal-18M surfacing maximal permissible tissue tensions for the 5 and 10 minute compartments were reduced (perhaps because they were incorrect in the earlier model). The target was attained at the expense of slightly longer decompression times when NDLs are exceeded. VVal-79 is suitable for implementation in Navy dive computers. The 2016 USN tables were modified to ensure consistency between tables and computers

The overall rates of DCS for the NDLs in the 2016 table, estimated by BVM(3) and NMRI98, are generally between 1 and 2% (1.1-2.2)

Few divers use the aggressive USN dive tables these days. USN computers are not available to the general public.

 

[Octopusprime]

I believe there's a class for that. Called "Tec 40" if I'm not mistaken.

So, this "lite deco" of which you speak. Do you carry enough redundant gas to meet any deco obligation you anticipate incurring?

What happens if you run into delays immediately prior to your planned ascent point?

I totally agree. Tec40 will get you up to 10 min of deco, redundant air source, proper gas planning and up to 50% nitrox.