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SurfLung
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First Name: Eben
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Personal Settings

Tue Jan 16, 2018 4:01 pm

Personal Dive Computer Settings
- My ZOOP dive computer has 3 levels of "Personal Settings" to compensate for any personal factors a diver may have that might present a greater likelihood for DCI (De Compression Illness). These factors are listed as follows:

• cold exposure - water temperature less than 20°C [68°F]
• the diver is below average physical fitness level
• diver fatigue
• diver dehydration
• previous history of DCI
• stress
• obesity

- The settings are P0, P1, and P2. Being overweight and 64 years old, I set my Personal Settings to the highest, "P2" level. So, how much of a difference does it make? Well at our Live Aboard Dive trip last Spring, it was very apparent that Jill and I were coming up to finish our dives at shallower depths earlier than the other divers. There was some concern of whether I was using my dive computer properly. So, I tried setting the Personal Setting to level P0 and looked at the Dive planner to see how much difference it would make in the No Deco time. And the difference is quite significant.

80 feet depth at P0 gives 28 mins
80 feet depth at P2 gives only 19 minutes

- I thought about leaving it set at P0 but then, the whole point of having the Dive Computer is to keep me out of trouble. I really DO have personal factors which might make me more sensitive to DCI. So, I set it back to P2, left it that way the rest of the trip, and had a ball. :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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ScubaLawyer
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Re: Personal Settings

Tue Jan 16, 2018 4:36 pm

Eben, are you saying I can't rely on my old set of square profile Navy dive tables anymore? :D Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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antique diver
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Re: Personal Settings

Tue Jan 16, 2018 7:20 pm

Eben, I think you are right to give a extra margin of safety. At 72 Francie and I have been using more conservative settings on our computers for several years, and generally spend a lot of time finishing a dive in shallow water. It was hard to give up some precious dive time after many years of pushing the limits, but I know I can't be diving to limits like I did many years ago.

The safety discussion reminds me of something about 35 - 40 years ago, and before electronic dive computers. In some instructor journal I read the rantings of one instructor that was teaching his students to just make one dive per day so they didn't have to calculate repetitive dives. He advised that was too dangerous for recreational divers anyway. :roll: I don't remember his name, but pretty sure he was on the east coast. Maybe Boston area.

We were already using the Navy Tables as a basis to make "multi-level" interpolations in the 70's, and thought he was just too lazy to teach table use properly. One of his reasons, however, did ring true... that was the fact that many new divers just can not remember how to use the repetitive tables for very long after their class if they don't stay active.
The older I get the better I was.

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luis
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Re: Personal Settings

Tue Jan 16, 2018 9:17 pm

antique diver wrote:
Tue Jan 16, 2018 7:20 pm

The safety discussion reminds me of something about 35 - 40 years ago, and before electronic dive computers. In some instructor journal I read the rantings of one instructor that was teaching his students to just make one dive per day so they didn't have to calculate repetitive dives. He advised that was too dangerous for recreational divers anyway. :roll: I don't remember his name, but pretty sure he was on the east coast. Maybe Boston area.

By any chance, you wouldn't happen to be talking about Fred Calhoun?
http://www.easy-diver.com/pages/crew.htm#capt
Luis

Buceador con escafandra autónoma clásica.

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antique diver
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First Name: Bill
Location: North-Central Texas

Re: Personal Settings

Tue Jan 16, 2018 11:23 pm

luis wrote:
Tue Jan 16, 2018 9:17 pm
antique diver wrote:
Tue Jan 16, 2018 7:20 pm

The safety discussion reminds me of something about 35 - 40 years ago, and before electronic dive computers. In some instructor journal I read the rantings of one instructor that was teaching his students to just make one dive per day so they didn't have to calculate repetitive dives. He advised that was too dangerous for recreational divers anyway. :roll: I don't remember his name, but pretty sure he was on the east coast. Maybe Boston area.

By any chance, you wouldn't happen to be talking about Fred Calhoun?
http://www.easy-diver.com/pages/crew.htm#capt
Thanks, Luis - it was Fred. Probably a great guy, and well respected, but his article really got my goat at the time. :?
The older I get the better I was.

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luis
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Re: Personal Settings

Wed Jan 17, 2018 6:47 am

Yeah, Fred has some different ideas. He is definitely a character. At time, he does have some interesting ideas.

He has written several small books about different diving topics. They are kind of interesting to read, and make your own opinion. Some stuff is good and all of it can at least get thinking.

When you mentioned "rantings", I had a good idea who it was. :lol:
Luis

Buceador con escafandra autónoma clásica.

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SurfLung
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First Name: Eben
Location: Alexandria, MN
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Re: Personal Settings

Wed Jan 17, 2018 10:49 am

- There's a long period of diving from the '70s to present that I wasn't diving and I missed the tech diving movement and repetitive table use. When I started back diving in 2011, I bought the tables and learned how to use them. But I bought a ZOOP dive computer right away and never actually used the tables to calculate repetitive dives.

- But I got interested in it lately. And by studying the repetitive dive tables and calculating prospective dives recently, I can see where you can get to a daily limit of 3 dives pretty easily. Counting the total dive time against the maximum depth (even though you might have spent most of the dive at much shallower depths) and running the tables... You end up with stage decompression on the third dive even with a good 2 hour surface interval between all dives.

- Considering that most sport divers might only dive 1-2 times per year, I can see where that dive instructor would recommend that they don't mess with more than one dive per day. They have enough trouble just remembering the basics.

- But our modern dive computers do the calculations and measurements continually, crediting you when the bulk of a dive is shallower than the max depth. I think an argument can be made that even a conservative Personal Setting will allow for more and longer repetitive dives than calculating from the old tables will allow.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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Ron
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Re: Personal Settings

Sun Jan 21, 2018 7:19 pm

One thing to remember too is that, on the USN56 tables, the 120 minute compartment controls your residual nitrogen time. Therefore, it takes 12 hours to wash out on Navy tables, which makes them actually not super great for repeat nondecompression diving. If you guys ever want evidence I can link you some articles, but all of this is factual. The DSAT tables, which are captured in PADI's RDP and in numerous modern dive computers, gives you much more credit for surface intervals because the 60 minute compartment controls the dive. Additionally, modern models typically have 12-14 compartments, while USN56 has only 6.

The short answer is that the PADI RDP, despite what anyone will tell you, is the best set of tables out there for nodecompression diving. Now for tech diving, I prefer Buhlmann tables or algorithm with gradient factors. These days I'm running low/hi 50/70.

There's no reason you cannot use new science with old dive gear. In the bahamas when we did Legends of Diving, I was making 3 dives a day on PADI's RDP with no computer which would have put me in deco on USN tables.

Not to down anyone, but personally if a diver cannot calculate how to do repeat dives, then I would not dive with them. If a diver understands basic math that little, then they should golf.
The impossible missions are the only ones which succeed. -JYC

jsmall
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Joined: Tue Dec 17, 2013 3:05 pm
First Name: John

Re: Personal Settings

Mon Jan 22, 2018 2:55 pm

what's a dive computer? does it hook to the J valve? :D

The nice thing about diving with vintage equipment is we can ascend 60 to 90 feet per-minute like our vintage manuals say. Those single hose guys with the fancy BC things have to go up at less than 30 feet per minute :) .

But seriously when I go to Bonaire where I am doing maybe 5 dives a day, is set my computer to the middle setting and don't push the bottom times. I am overweight, 60 years old and I could be in better shape, but I don't drink so I think that helps with the dehydration part. When I am scallop in New England I still keep it in the middle but make a slow assent and a long safety stop. I've never had a problem.

John

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luis
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Re: Personal Settings

Mon Jan 22, 2018 4:14 pm

For anyone that is interested in any decompression theory, I would recommend reading: “Deco for Divers”: A Diver's Guide to Decompression Theory and Physiology, by Mark Powell.

https://www.amazon.com/gp/product/19054 ... UTF8&psc=1

It is a really easy book to read. The theory is very well explained and it contains very up-to date information from research being conducted by a number of other hyperbaric medicine researchers. Well, I just noticed the latest edition is almost 4 years old, but let’s just say it is as up-to date as you are going to find in a published book.

I read it when the first edition came out and now there is a newer edition (came out in 2014) that I just ordered. It is about time for me to read it again.
Luis

Buceador con escafandra autónoma clásica.

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