Nitrox course. What's the point?

[Angelo Farina]

I reset the bezel to time the assent, I’m not using navy tables, I’m using IDeco Pro. Bottom time is from leaving the surface till you start the assent. I posted an example. I have all possible run times on a slate, usually 3, if conditions are poor I’ll leave early. If conditions are very good I’ll stay longer.

Thanks for the clarification.
So you are not using tables, you are using a computer...
But you are not carrying the computer with you, you pre-calculate some diving profiles.
This is what I see often done by "tech" divers.
My concern with this approach is: what do you do if, for any reason, you are doing a dive which exceeds the max depth, or the bottom time, or the ascent time of your pre-computed profiles?

 

[Celt]

Thanks for the clarification.
So you are not using tables, you are using a computer...
But you are not carrying the computer with you, you pre-calculate some diving profiles.
This is what I see often done by "tech" divers.
My concern with this approach is: what do you do if, for any reason, you are doing a dive which exceeds the max depth, or the bottom time, or the ascent time of your pre-computed profiles?

My dives are to a hard bottom and are planned to the max depth. Very important not to exceed the max possible time. I really don’t understand why people can’t maintain the assent time. Why would it be slower?

 

[Angelo Farina]

My dives are to a hard bottom and are planned to the max depth. Very important not to exceed the max possible time. I really don’t understand why people can’t maintain the assent time. Why would it be slower?

It happens.
You find something interesting to see or to photograph while ascending. You stop waiting for your buddy who remained some meters below you.
You can also easily exceed the max depth, if the sea bottom is not flat.
A good diver should not exceed the planned bottom time, but again sht happens. I remember that once I got entangled in multiple fishing lines while there was just one minute before the end of our planned dive time. My wife did cut the wires and freed me, but it did take three minutes at least, so we simply went to the next time on the table...
Our procedure did also take into account anomalous effort and consequential air consumption. Whenever after reaching the first deco stop we were watching the SPG and finding less air than normal, the rule was to switch to a table corresponding to a longer time.
With just 3 pre computed profiles it becomes difficult to be able to manage all these possible deviations...

 

[doctormike]

Thanks for the clarification.
So you are not using tables, you are using a computer...
But you are not carrying the computer with you, you pre-calculate some diving profiles.
This is what I see often done by "tech" divers.
My concern with this approach is: what do you do if, for any reason, you are doing a dive which exceeds the max depth, or the bottom time, or the ascent time of your pre-computed profiles?

One of the main things about tech training isn't learning gear or deco math. It's mindset. That's why I think that tech training is great even for people who will never do "big" dives.

The idea is that you HAVE to be situationally aware and you HAVE to know and keep to the plan, even though you have calculated some contingencies for overstaying depth or time a bit. There simply is no reason to go beyond your planned contingencies (barring rare disasters like downcurrents or entanglements). If you can't commit to doing this, then you shouldn't be doing tech dives.

 

[doctormike]

It happens.
You find something interesting to see or to photograph while ascending. You stop waiting for your buddy who remained some meters below you.
You can also easily exceed the max depth, if the sea bottom is not flat.
A good diver should not exceed the planned bottom time, but again sht happens.

The point of tech training is that none of this should happen. If you exceed your planned bottom time, then by definitely you were not being a "good diver", at least on that day.

Entanglements are different, it's not possible to plan for every disaster, although if you aren't able to cut yourself free of an entanglement, your N2 loading and deco requirements quickly become the least of your problems.

 

[Angelo Farina]

One of the main things about tech training isn't learning gear or deco math. It's mindset. That's why I think that tech training is great even for people who will never do "big" dives.

The idea is that you HAVE to be situationally aware and you HAVE to know and keep to the plan, even though you have calculated some contingencies for overstaying depth or time a bit. There simply is no reason to go beyond your planned contingencies (barring rare disasters like downcurrents or entanglements). If you can't commit to doing this, then you shouldn't be doing tech dives.

I agree entirely.
In fact I am not a tech diver. I never exceed the rec limits for which I was certified and trained...
The method we were taught allows for significant modifications to the original plan, with no other consequences than some longer deco stops.

 

[doctormike]

I agree entirely.
In fact I am not a tech diver. I never exceed the rec limits for which I was certified and trained...
The method we were taught allows for significant modifications to the original plan, with no other consequences than some longer deco stops.

I'm not sure what you mean by deco stops if you aren't trained as a tech diver. What method are you referring to?

 

[boulderjohn]

The point of tech training is that none of this should happen. If you exceed your planned bottom time, then by definitely you were not being a "good diver", at least on that day.

Entanglements are different, it's not possible to plan for every disaster, although if you aren't able to cut yourself free of an entanglement, your N2 loading and deco requirements quickly become the least of your problems.

Yes, you should dive your plan, but you also have to be prepared to deal with things that don't go according to plan. That idea should be part of your planning. You cannot go into a dive thinking that "I am so damn good that nothing can go wrong, so I don't have to plan for it."

 

[doctormike]

Yes, you should dive your plan, but you also have to be prepared to deal with things that don't go according to plan. That idea should be part of your planning. You cannot go into a dive thinking that "I am so damn good that nothing can go wrong, so I don't have to plan for it."

That's what I was referring to when I talked about contingency plans. I would never say that nothing can go wrong. What I was responding to was the idea that it's OK to not worry about the plan because you have a magic bracelet that will figure things out if you forget the plan to take a picture or inadvertently break through your planned bottom depth, as was mentioned in the post I was answering.

Of course, you know this, but for others reading the thread - at some point, you have to stop making plans for worse and worse accidents, because you would never get in the water. 10 seconds of entanglement before your planned ascent? No change. 10 minutes of entanglement? That's what your contingency deco plan is for. An hour? Hope you have a fresh scrubber.

 

[Celt]

It happens.
You find something interesting to see or to photograph while ascending. You stop waiting for your buddy who remained some meters below you.
You can also easily exceed the max depth, if the sea bottom is not flat.

For years I worked salvaging nonferrous metals from WW1 wrecks deep on air, we used high pressure lances, cutting gear and explosives, not once did I stray from the dive plan for the simple reason if you did you were going to get hurt or killed. So for me aimlessly wandering from a dive plan seems crazy.