How long of SI after the computer dies?

[TimAZ]

Let me suggest a different twist on this. Forget the computer for a minute. There are two places for a diver to off-gas nitrogen: Underwater and on the surface. The "Surface Interval" is the time a diver is off gassing on the surface. As to underwater off-gassing, there are alternatives to the popular 3 minutes at 15' that can effect how much N2 you surface with, and therefore effect the amount of surface off-gassing one needs to be concerned about.

Say for example that you do a dive to 100', but instead of going straight up to 15' for 3 minutes, you do a deep stop, and then some stops at 10' intervals along the way up. And then, say you take 6 minutes to get from 20' to the surface. Would you come out "cleaner" than someone who just does a 3 minute stop at 15'? Would this then effect the amount of surface-off gassing you would need to take into account on the next dive?

Well, sure it would.

What I am suggesting here is that the amount of time on the surface between dives is really less important than the amount of time spent cleaning up before you get out. Blindly following some agency "rule" that is so general that it's rarely applicable to any specific diver isn't how I would suggest approaching it. I would prefer to think it through.

Nicely put Rick.... Imagine that... divers thinking for themselves.

(Some) Divers thinking for themselves scares me. I'm reminded of too many people (myself included) who decided after about 50 or 60 dives that they are God's gift to diving and rules simply did not apply to them. Rick of course is more than qualified to make these kind of judgements. I'd just hate to see some 50 dive superhero thinking s/he's qualified too. (shrug)

BTW, I recommend getting a spare computer on ebay and stuffing in a bc pocket.

 

[Gary D.]

Good one Rick. The only problem with it are way to many divers are Trailers and fewer and fewer are becoming Tow Vehicles.


Gary D.

 

[MBH]

Seriously, I do like Steinhoff's tables

Me too.
I keep two copys of the min deco tables in my wetnotes. Tables, a watch, and my bottom timer is all I really need. I do carry a computer but it's really just there to record the dive profile for download to my PC.

Just because my computer is bent dosen't mean that I am.:no

 

[Oriskany Divemaster]

I've found that by using a fresh computer on each dive, my surface intervals are very minimal and my dives are much longer........i'm kidding, of course. There really is no surface interval necessary with this approach.

I'm kidding...about it all. I had a guy who got back aboard after his first dive and couldn't figure out why his computer was still beeping. He'd blown his stop and crapped out his computer for 24 hours. So he asked if I had one he could borrow on his next dive.

"Next dive?" I replied. "Your next dive is tomorrow." And not because his computer locked up, but because the knucklehead blew his deco stops. (Not safety stop, but deco stop.)

But if your computer dies, just dive the tables for the rest of the day and get a new one and, if possible, a backup when you get ashore.

 

[frankc420]

I feel that all times that are taught by the agencies are meant to be on the conservative side.

Going to the tables and assuming your in the Z group sounds like a good plan and is still leaning toward the conservative side, IMO. It really makes a difference if your making more than 3 long, deep dives in that one day.

 

[Charlie99]

When he found his computer had failed and wiped out the previous day’s dive profiles his comment was he was not diving for 24 hours.

If he was out of the water for a week, and his computer died before his first dive of the day, would he stay out of the water another 24 hours?
Clearly, if you are going to apply the very conservative 24 hour SI, at least you should apply it starting with the end of the previous dive.

...... If I dive the PADI RDP for something like 40’ and 180 minutes (or the equivalent) I am a “Z” diver, worst in class for NDL diving. However, after a 6 hour SI I am an “A” diver, and after 12 hours I am off of the charts. That should be an indicator where I could safely begin to use tables as a replacement to my computer.

So here is my thought, I finished a day of dives, always completing my safety stop; never violating NDLs and the next morning my computer has wiped out the history or died. I do not brainlessly throw out a day of diving, I go to a guaranteed fixed point and dive tables, namely: I start the repetitive dive program as an “A” diver on tables (provided it has been at least 6 hours SI) and enjoy my vacation, well within the proscribed safety limits I was trained with.

Am I wrong?

Your logic is correct. This is the same plan I would use in the case of computer failure, which so far has not happened to me in 600+ dives.

Provided I have stayed within NDL on prior dives, my fallback plan is to simply assume prssure group Z and go from there. This works even if the computer fails after the 1st dive of the day. The only other thing that you have to decide is whether or not the special W,X,Y,Z rules apply (min 1 hour SI for a 3 or more dive sequence where any dive hits PG W or X; min 3 hour SI for 3 or more dives where any one of them reaches Y or Z). Since you reach these pressure groups only after very long dives, for most divers that won't be a problem.

Charlie Allen

 

[MXGratefulDiver]

If I'm on vacation and my computer craps out on me, ain't no way I'm skipping a whole day of diving. Given the scenario described in the OP, you've probably already been out of the water at least half a day anyway (sleeping counts as surface interval time, ya know) ...

I'd go diving ... adjust my profiles for shallower dives, make longer intermediate stops on the ascent, breathe nitrox if possible ... but I'd dive.

... Bob (Grateful Diver)

 

[Garrobo]

Speaking of making additional stops when coming up from 100 feet, on my last trip I dove the Eagle at Islamorada. We stopped at 50 feet for a couple minutes, 30 feet for a couple and 15 for three. Worked for me.

 

[--tom--]

Thank you for the well thought out answers. Thank you also for the SSI and Naui standards. If you see a flaw in logic, please let me know.

 

[1_T_Submariner]

I agree with the switch to the tables as a Z diver.

If I where in a place with shallow reefs I would do a couple of shallow dives. Not sure I would do a deep dive with out 6-8 hours out of the water.