How to plan second dive of the day using a computer

[redacted]

I'm not sure what you mean by that? Enter plan mode, input SI, scroll through depths... see the NDLs. Works fine on multiple dives. That basic function, or more, has existed on every dive computer I've used.

None of my computers have the capability to input an SI time but all are older models (Scubapro EDI, Tusa IQ-300?, Oceanic Data +, Oceanic VEO 250). So all NDL's to support dive planning are based on current gas loadings.

I just looked at a more current Oceanic computer and, as with all my older DC's, SI is a computer post-dive output; not a user input that would allow SI to be paramaterized for future dives. What computer(s) are you using?

 

[DevonDiver]

What computer are you using?.

All my Suunto's allow a SI to be factored into planning, including my ancient Vyper.

 

[mheaster]

User stated in another post that he had a Mares Puck

From that manual:

"PLANNING: SCROLLING OF NO
DECOMPRESSION LIMITS
This function allows the user to scroll through
the no decompression limits, automatically
taking into consideration the residual nitrogen
level in the tissue compartments from a
previous dive.

The times displayed take into account all the
settings under SET MODE.
Scroll through the main menu to PLANNING.
Press and hold the button to enter PLANNING

Pressing the button increases the depth shown
by three meters each time, up to a maximum
of 48 m (157 ft).

For each depth, the display shows the
corresponding no decompression time
expressed in minutes.

If “EAN” mode is selected, the display also shows
the programmed oxygen percentage value.

The maximum depth allowed in this case
varies as a function of the % O2 and maximum
PPO2 that have been entered.

Upon reaching the maximum depth, pressing
the button again moves to ESC mode.

Press and hold the button to return to the main
menu.

Note:
The Plan function will only be active after
having selected AIR or EAN mode in SET
DIVE."
​

Looks as if, there is no method to Input additional Surface Interval (SI) Time, it just calculates the amount of NDL Time allowed for a new Dive to a specified depth based on current amount of SI?

(This constantly and automatically takes into account and adjusts for amount of NITROGEN loading that occurred on previous dive/s and amount of off-gassing that has occurred on surface Interval since last dive)


So when a Dive Operator states the 2nd dive is say to max depth of 70 feet for no longer than 35 minutes (merely an example), you would have to see if your computer currently would permit such a dive and if not, wait additional SI time until your computer would allow you and your buddy to make that length of dive (OR you both agree to dive something shorter) assuming both buddies' computers would permit it).

If this still seems cloudy, I would strongly suggest a finding an Instructor to provide you a Dive Computer class (based on your computer) or at least run you through some dive computer planning scenarios in a classroom environment before heading off on a dive trip!

 

[FPDocMatt]

Looks as if, there is no method to Input additional Surface Interval (SI) Time, it just calculates the amount of NDL Time allowed for a new Dive to a specified depth based on current amount of SI?

So when a Dive Operator states the 2nd dive is say to max depth of 70 feet for no longer than 35 minutes (merely an example), you would have to see if your computer currently would permit such a dive and if not, wait additional SI time until your computer would allow you and your buddy to make that length of dive (OR you both agree to dive something shorter) assuming both buddies' computers would permit it).

I see. Thank-you for explaining it.

By the way, even though I re-read the portion of the manual you quoted, it still didn't make sense to me until you explained it. So I don't think advising people to read and re-read their dive computer manual is going to make people fully cognizant of the use of their dive computers.

I don't understand why the Dive Computer Training site won't allow you to purchase a class. Weird.

It did allow me to purchase the class "Intro to Dive Computers", which is interesting. How the 16 compartments work, etc. It seems odd to me that the "dominant compartment" is not necessarily the fastest or slowest compartment. I still haven't figured that one out.

 

[Dirty-Dog]

Ah I see, thanks. So before every dive you go to PLANNING, and enter the surface interval since the last dive, and the info about the dive you're about to do, and it tells you how long you have at that depth. Cool!

I went to the website for Dive Computer Training, and it said I can't do the training without an activation code, that I can't purchase the activation code, but rather have to get it from the store that sold me the computer. So I emailed the outfit in Spain that sold it to me to get it. We'll see how that goes.

I read the manual, but didn't understand it. I'll try reading it again. The manual is pretty minimal, and seems to assume that you already know how to use dive computers.

With the computers I have personally used (Aeris, Suunto, and Uwatec) you don't actually enter the SI. The computer is constantly tracking your nitrogen load (etc) while you're diving. It continues to do this during your SI, as you offgas. When you enter the planning mode, it will either allow you to enter the max depth for your next dive and show you the current NDL for that depth, or scroll through various pre-set depths and show the current NDL for each. If the NDL for the depth you plan to hit is less than your desired time, then you wait. Recheck. When the NDL is longer than your planned dive, you're good to go.

The plan, of course, is based on a square profile and max depth. Once you actually hit the water, your NDL will be constantly updated and adjusted based on your real profile.

The manuals I've read all seem to be written by someone for whom English is a second (or third...) language.

 

[DuboisP]

Are you saying I can only use the computer to plan the first dive of the day? Then what good is it? That makes no sense. In that case, why does it ask me for a surface interval?

U.S. Navy Diving Manual rev.6 (15 APRIL 2008)
http://www.supsalv.org/pdf/DiveMan_rev6.pdf

 

[Ste Wart]

i don't understand why people purchase computers without knowing decompression principles.

The OP is PADI AOW. Last time I checked they don't teach decompression on those courses, however PADI OW does have a computer option.

Another way of guessing that the OP doesn't know about decompression is checking which forum this is in 'BASIC scuba discussions'

EDIT:

You have 2 options:
1) Plan the dive using tables, use the computer as a depth gauge and timer; ignore the NDL's on comp
2) If your buddy is using a computer; take yours, but use his as the guide to NDL's (which would be following the most conservative.)

 

[IanBrit]

Matt,

It would help other posters on the board if you were to post the make and model of the computer you bought. All computers are different. The fact it supports 16 compartments indicates it's a reasonably advanced model and so the chances are that it supports a dive planning mode. Be aware that this is still going to plan a square profile and will therefore predict the 'worst case' NDL. If you want to understand what the compartments means, you're going to have to dig deeper in decompression theory.

 

[rhwestfall]

http://www.scubaboard.com/forums/co...410616-questions-about-my-new-mares-puck.html

 

[tc]

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