Deco diving without a written out dive plan?

[Tassi Devil Diver]

Using two computers I don't take a written copy of the dive plan with me on a deco dive, I review the plan on MultiDeco to ensure I have enough deco/ bailout gas. I generally find I can do a bottom time with a time to surface of around 30-40 minutes at depths of between 30-50m with my standard deco configuration rig and happy to do this without reviewing my plan on MultieDeco . If I am planning a dive with greater deco or deeper I will review my dive plan more closely on MultieDeco.

 

[Nasser]

I dive within my dive plan using a Petrel in OC Tec mode and a Suunto in gauge mode, and as backup a slate with lost gas scenarios and laminated cards like a matrix that have a series of varying bottom times and different max depths - similar to this example:

 

[Peter69_56]

I run 2 Petrel's and do a Multideco and ensure I have a good idea of the first stop and last stop deco time. Usually the other stops are all around 1 min each up to the last few. Never had a failure to date. If you compare this to rebreather divers, they usually use 2 computers, one integral to their breather and the second either integral or stand alone. Given the number of rebreather divers now and the way they usually operate, I am ok with 2 computers and no tables (as long as I have a fair idea of my dive profile). Both my PC are the same so if one is set wrong it quickly becomes apparent there is an issue.

I think some are comfortable with 2 computers only, some want 2 computers and tables, others want a computer and tables. Each to their own. No one setup is "right", and the rest wrong.

 

[MXGratefulDiver]

Would you ever do a deco dive without a dive plan and contingencies written out on a slate or in wet notes?

Yes ... but it would depend on the nature of the dive and how familiar I am with the profile. My last deco dive was on a wall where I planned to descend to about 170 fsw and make a very slow ascent while looking for sixgill sharks. I racked up roughly a 30-minute deco obligation by the time I got up to where I could switch to my EAN50 bottle. No written plan ... but I've done the dive often enough to know how much gas I'd need and what my contingencies were. And FWIW - it was a solo dive, on sidemount.

... Bob (Grateful Diver)

 

[fsardone]

Thanks, Fabio. I click the link and it says I don't have permission to access that page. It appears to be in the Tek2Tek forum, which I am not eligible to join yet. I haven't even finished AN/DP yet.

Sorry,
I tought you could not post but yu could read the existing posts.
I will not copy paste the whole discussion (which was a bit limited) but I am posting the poll results:



You will see that most people have 2 computer and also tables.

When I dive CCR I use 2 dive computers: the rebreather one and the backup, I also have computed my deco estimate and I have a clue on whath should happen but I have too many variables (constant ppO2 or Bail out so constant fraction). I do not plan for too many emergencies (2 broken computers, bail out and loss of one decompression gas means it was my day to die or at least get bent).

When I dive OC I use tables (most of my profiles are squared ones in the 60 meters 200' range), using multigas computer as backup, I also dive with a dive timer depth meter.

I use same config when I dive solo ...

Cheers

Fabio

 

[shoredivr]

In the hugely unlikely event of computer and bottom timer going for a crap, I was taught to know how many breaths I take in a minute and use breath cycles as a rough form of timer (sure this is dependent on breathing rate remaining constant). Breath cycles combined with knots tied every ten feet in the SMB line for rough depth estimation, plus written tables. Better than a slap across the belly with a piece of wet cod, as they used to say.

 

[stuartv]

In the hugely unlikely event of computer and bottom timer going for a crap, I was taught to know how many breaths I take in a minute and use breath cycles as a rough form of timer (sure this is dependent on breathing rate remaining constant). Breath cycles combined with knots tied every ten feet in the SMB line for rough depth estimation, plus written tables. Better than a slap across the belly with a piece of wet cod, as they used to say.

I was contemplating the possibility of having both computers/bottom timers crap out and how to deal with it. Ratio Deco seems like it would give me at least some idea of an ascent profile but then the question is how to implement it without a timer or a depth gauge. I had thought about simply counting out the minutes. If you know your breathing cycle, that's cool. For me, counting off seconds would probably be pretty close. I am also a musician and do spend time practicing being able to count various tempos, with 60 beats per minute being the most common tempo I practice.

But, if you have knots in your line every 10 feet and you shoot a bag then start ascending on your line, when you come to a knot, how do you know which knot it is? 1 knot at 10', 2 at 20', 3 at 30', etc? A knot and then use a Sharpie to make hash marks on the line?

 

[Germie]

Yes and no. First I have dived to a depth of 112m without computer, just 2 bottomtimers and a written plan in wetnotes. That works.
Then I bought a computer and still dived the written plans.
Now I sometimes dive with 2 computers and don't take a written plan with me. But I have calculated things with a decoplanner: bottomtime and total divetime and oc gas needed.
I use ratio/pragmatic deco too sometimes as deco is not absolute science. An +5m or +5 minute backupplan is not more than a +X minutes in my wetnotes. I will do half of time on 6m and rest on the shallowest stops between 21m and 9m. For me no need to write a complete extra plan with all runtimes in my wetnotes.

When teaching: A plan is made and written on wetnotes/slide. A backupplan is made too, including amount of gas needed. I explain a little bit pragmatic deco too. But as I don't teach dir we use runtime/stoptime tables. Students don't need to have computers, just 2 bottomtimers are ok. When we made a written plan, I always take a computer with me, I have computers, so why not take with me? The dives made in a course are conservative and most times not the maximum bottomtimes are reached, but we do the deco as we did maximum bottomtime. Follow the written plan.
I think it is good for every diver to know how to dive a written plan with runtimes/stoptimes. Diving on tts on a computer can give problems when wrong gases in it, or wrong PO2, or such things. A computer is a usefull tool, but not foolproof.

 

[shoredivr]

But, if you have knots in your line every 10 feet and you shoot a bag then start ascending on your line, when you come to a knot, how do you know which knot it is? 1 knot at 10', 2 at 20', 3 at 30', etc? A knot and then use a Sharpie to make hash marks on the line?

Bingo, one knot at ten, two knots spaced 1/4 inch or so apart at 20, three knots 1/4 inch apart at thirty, continuing every ten feet down to seven knots spaced 1/4 inch apart at 70. The 1/4 inch space is so I can count the knots easily when wearing thick dry gloves in the cold water we have here in the Great Lakes. Worst case scenario somehow lost both mask and backup, unlikely I know.

Sharpies just bleed all over once the line gets repeatedly wet. I like the tactile reminder of the depth that knots provide, though the knot tying was an interesting exercise in the numerous reels and spools in my possession. Maybe this is the most anal post I've ever made lol.

 

[DevonDiver]

But, if you have knots in your line every 10 feet and you shoot a bag then start ascending on your line, when you come to a knot, how do you know which knot it is? 1 knot at 10', 2 at 20', 3 at 30', etc? A knot and then use a Sharpie to make hash marks on the line?

I put knots at 3m increments. It's primarily for wreck diving (zero viz references on safety spool), but the increments also serve as a reference for stops also.

3m - 1 knot
6m - 2 knots
9m - 3 knots
12m- 1 knot
15m- 2 knots
18m- 3 knots

In addition to this, I wear a dive watch. I often carry an analogue depth gauge also - sometimes just because I think it's fun to run ascents with a watch and needle.... but it's also a foolproof and reliable back-up.