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

[Killerflyingbugs]

This, then no one can ride by and steal it.

You can also inflate the SMB or lift bag just enough to keep it neutral at your stop depth.

 

[jseyfert3]

I can't believe I read this entire thread. My wife is working today and it's raining so I didn't want to bang on the stuck rusty bolt on my car I need to remove for very long, so I read this instead...

The navy tables are funny, too. Five minutes for anything past 150'?

According to revision 7 of the USN Diving Manual (2016), this isn't the case. It steps down from 10 at 140' to 5 at 190' as 10, 8, 7, 6, 6, 5 minutes, every 10'.

As an interesting note, I saw a lot of mention of USN tables, and what people thought the USN diving practices are. While looking at the tables in revision 7 of the USN Diving Manual, I found the following interesting tidbits related to stuff people have mentioned in this thread about NDLs and such. From page 7-2, Normal and Maximum Limits for Open Circuit SCUBA Diving:

• 60' or more requires a standby diver with more than 100 SCF of air
  
• 130' is max depth without approval of the OIC.
• 190' is maximum working limit
• NDL is not to be exceeded during routine dives, deco requires approval of OIC and closed circuit is preferred for deco dives
• Exceptions to above limits require approval in writing

Other interesting requirements

• A minimum of 4 personnel are required for SCUBA dives. Dive supervisor, diver, diver tender, and standby diver
• Divers usually buddy and end the dive if buddy is lost
• For DOD civilian divers deeper than 100' or outside NDL a decompression chamber has to be within 5 minutes of the dive site (but not for military divers) except when conducting uniquely military operations.
• Dives are ended at 500 PSI

 

[KenGordon]

I can't believe I read this entire thread. My wife is working today and it's raining so I didn't want to bang on the stuck rusty bolt on my car I need to remove for very long, so I read this instead...


According to revision 7 of the USN Diving Manual (2016), this isn't the case. It steps down from 10 at 140' to 5 at 190' as 10, 8, 7, 6, 6, 5 minutes, every 10'.

As an interesting note, I saw a lot of mention of USN tables, and what people thought the USN diving practices are. While looking at the tables in revision 7 of the USN Diving Manual, I found the following interesting tidbits related to stuff people have mentioned in this thread about NDLs and such. From page 7-2, Normal and Maximum Limits for Open Circuit SCUBA Diving:

• 60' or more requires a standby diver with more than 100 SCF of air
  
• 130' is max depth without approval of the OIC.
• 190' is maximum working limit
• NDL is not to be exceeded during routine dives, deco requires approval of OIC and closed circuit is preferred for deco dives
• Exceptions to above limits require approval in writing

Other interesting requirements

• A minimum of 4 personnel are required for SCUBA dives. Dive supervisor, diver, diver tender, and standby diver
• Divers usually buddy and end the dive if buddy is lost
• For DOD civilian divers deeper than 100' or outside NDL a decompression chamber has to be within 5 minutes of the dive site (but not for military divers) except when conducting uniquely military operations.
• Dives are ended at 500 PSI

When this thread started the version 6 manual still applied. I think its tables were rounded to 5 minute durations. The new manual is very new.

 

[scubadada]

When this thread started the version 6 manual still applied. I think its tables were rounded to 5 minute durations. The new manual is very new.

See my post #339. They used "smoothing" to generate a "new" USN57 table. The VVal 79 algorithm matches these values quite closely to generate the 2016 USN tables and computer algorithm.

 

[jseyfert3]

When this thread started the version 6 manual still applied. I think its tables were rounded to 5 minute durations. The new manual is very new.

Actually not, but close enough I'd be splitting hairs pointing it out.

Certainly it may not have been downloadable yet, as nobody posted on SB about it till the 17th, a post I found on my honeymoon and when I realized the manual could be downloaded by anyone. I preceeded to read the first 200 pages on the flight back from Grenada.

 

[KenGordon]

Actually not, but close enough I'd be splitting hairs pointing it out.

Certainly it may not have been downloadable yet, as nobody posted on SB about it till the 17th, a post I found on my honeymoon and when I realized the manual could be downloaded by anyone. I preceeded to read the first 200 pages on the flight back from Grenada.

Now I just think you are a ****.

Edit - maybe that is a bit strong. While the issue date might be in January 2016 I really don't think it was out when this (rather long) thread started. For sure when I was recently arguing with tbone about effects of altitude revision 6 was the latest available at the navsea site. However the main point is that when talking about "US Navy Tables" the participants in this thread were talking about the tables and procedures in the revision 6 manual. The revision 7 manual has made changes, some of those are discussed in the paper about vval79 tissue limits. Those developements are properly interesting things, especially when people make assumptions about the relative conservatism of profiles by comparing them to navy tables.

 

[lowviz]

...//... The revision 7 manual has made changes, some of those are discussed in the paper about vval79 tissue limits. Those developements are properly interesting things, especially when people make assumptions about the relative conservatism of profiles by comparing them to navy tables.

I'll be the first to admit that making comparisons the Navy Tables immediately places one in a dicey position. But the alternative comparisons all spin wildly out of control due to many undefinable (as yet to be better defined) variables. RGBM?

First approximation: I see the Navy Tables as an operational recipe that is intended to bend people evenly throughout its range.

Imagine my delight when I first saw that 7 better attended to the deeper portions...

 

[lowviz]

To be explicit:

Here is how I determine where my "lite deco" ends and hard deco begins: Type six 2's into a calculator then divide by your intended depth twice. Example: For 120 ft, you should get 15. That approximates how many minutes to the USN's NDL at that depth.

The recent change in the navy tables brings me into much closer agreement with them at the deeper end. Most satisfying.

So now that I have an aggressive NDL, I pick a very conservative algorithm and follow its deco schedule for that same NDL. With this, I allow myself to presume that if anything should go "paws up" on my dive, I'll just surface as best I can and get onto my 100% O2.

 

[scubadada]

To be explicit:

Here is how I determine where my "lite deco" ends and hard deco begins: Type six 2's into a calculator then divide by your intended depth twice. Example: For 120 ft, you should get 15. That approximates how many minutes to the USN's NDL at that depth.

The recent change in the navy tables brings me into much closer agreement with them at the deeper end. Most satisfying.

So now that I have an aggressive NDL, I pick a very conservative algorithm and follow its deco schedule for that same NDL. With this, I allow myself to presume that if anything should go "paws up" on my dive, I'll just surface as best I can and get onto my 100% O2.

So that just works on the 1st dive, right? What do you do for repetitive dives?

 

[lowviz]

Indeed, that is nothing more than the justification for where I end "lite deco". I continue to follow the same DC/algorithm for all subsequent dives.

What we all need is a biological sensor that directly measures dissolved-nitrogen induced tissue stress.