Deco Procedures

[Lost Yooper]

Let's see if we can get a thread started in which we describe the deco procedures, contingency plans, and other relevant stuff that we do for our dives.

Who wants to go first ?

Mike

 

[Ari]

Can't wait to read it, though.

I can use the info.

Ari

 

[100days-a-year]

Are we assuming the this is a "planned staged deco dive"?And are we looking for a procedure from site selection to equipment configuration to dive planning to pre&post dive briefings?Or just from the point of entry?Set up some parameters and we'll get started.

 

[Lost Yooper]

I went through how I go about setting up a deco profile with contigencies on the Nitek 3 thread. I know how UP goes about it from my discussions with him via e-mail. I was just wondering if anyone had some "unusual" or different ways they approach a deep dive. How they choose their bottom mix, deco mixes, and how many variables they plan for.

For example:

Some people choose to use O2 only for deco. Others use 50/50 and O2, and others use only 50/50.

Some people might use the rule of thirds, halves, or be on the boat with a certain amount of gas.

Etc...

I haven't been around much the last couple days and won't be around for the next few days, I don't think. I just wanted to start something as there seemed to be some interest from others. I'll chime in when I can.

Mike

 

[ericfine50]

Well, with the selection of deco gas, it depends on the depth of the dive. I usually use 100% or 50/50 (most dives 150 ish range). For backgas, I use 1/3rds. And water temp plays a big roll in my in water time.

Eric

 

[MikeFerrara]

I take it our replies should be shorter than the average book? I’ll outline some basics of what I do. I hope this thread sees a lot of action. I’m always interested in hearing how someone else does it.

Computers/bottom timer
I carry two computers. The primary is a Zeagle status 2. They are primarily used as bottom timers. However, since we’re not usually at our max depth for the entire time the computer can provide a bailout option (this is not a substitute for a table based bailout plan).

Software/tables
I currently use GAP and Voyager. I like GAP because of the deep stops it incorporates. GAP will also automatically generate contingency tables including accounting for lost deco gasses. Voyager has some nice features but if you want deep stops you must add them manually. I am interested in getting a copy of the Abyss software because of the model used.

Deco gasses
I prefer 50/50 and O2. For shorter/shallower dives using air or nitrox for bottom gas I will use only the O2. For dives requiring deeper deco I add a bottle of 50/50. I haven’t done any dives that really call for more than two deco gasses. Also, we're usually not using hypoxic mixes. I guess for some dives it might make sense to have 50/50, a deeper gas and hang the O2. That would get you off the bottom mix sooner without having to carry a ridiculous number of bottles. I carry deco gas in an AL 63 and/or AL 80. Yes that usually gives me enough gas for several dives. I don’t find the size an inconvenience, in a pinch the tanks can be used for other purposes and getting O2 fills on the road can be tough.

Planning
I always carry schedules for variations in bottom time and depth including a short bailout. The exact variations depend on the dive and the perceived risks. When using multiple deco gasses I have schedules for the loss of either gas. When air or EANx is the bottom gas and there is only one deco gas I have a schedule for doing deco on bottom mix. However, sometimes my primary schedule is based on bottom mix as a deco gas (conservatism) and the accelerated schedule is a bailout.

I'm going to skip all the other aspects of planning because I'm tiered of typing.

Looking forward to hearing how the rest of you do it.

 

[Waterlover]

I have chosen 50/50 and 100% O2 as Standard deco gases. I may throw in some 32% for the new NAUI RGBM tables to try them. Right now I have preplanned tables for certain dives I do alot. The 2 I have laying here in front of me are examples: 170ft dive using 22/25 trimix. Bottom times are figured in 5 mintue increments from 15-35 using standard deco gases.total run times range from 33-87 minutes. on the back of the tables I have the bailout schedules timix only- trimix and 50/50 and trimix and O2. The other table is a cave dive, Cow Springs. This table is a preplanned mulitlevel dive with stops starting at 40 FT skipping the 30ft stop(due to the restriction in the cave) and finishing with 20 and 10 ft stops. This table uses 32%EANx bottom mix and O2 for deco. Bottom times range from 50 to 100 minutes, runtimes then vary from 69-155 minutes. Also on these bailout is the loss of my O2 this has runtimes of 82-206 minutes. There are alot of assumptions on these tables and depth varies from 60 - 105 ft. these tables are printed out and laminated. I carry 2 copies one in my pocket as backup and one on my arm or light head as primary.
These tables are calculated from Erik Bakers VPM/GF Buhlman ZH-L16B/1.0micron/88%m program. I believe Vplan will generate the same tables.I haven't played with Vplan to calculate them yet. Depending on the dive my END may vary between 100 -130 ft usually LESS Than 100 though. There's my $.02.
Ken :bonk:

 

[TexasMike]

For the uneducated ones, after you generate your tables, what means do you use to "carry" them with you?

 

[Waterlover]

My tables are printed then laminated. I carry one of them in my pocket. The other is attached to a velcro strap on my arm or duct taped to my light head.
Ken

 

[TexasMike]

Originally posted by Waterlover
My tables are printed then laminated. I carry one of them in my pocket. The other is attached to a velcro strap on my arm or duct taped to my light head.
Ken

Are cutting tables for each dive, or diving the same profile each time? Or, in your laminated set, do you have a table series that covers the different profiles?