Quiz - Recreational Dive Planner™ - Max Time

[scubadada]

I'm not quite clear on the minutiae, even towards myself.

If every compartment follows a standard exponential curve, how can the 60 or 120 min compartment decide SI credit and not the 480 min compartment?

So, I think we are talking about different things. Perhaps, go back and read @boulderjohn post Quiz - Recreational Dive Planner™ - Max Time He gives a more detailed explanation than I tried to do

 

[Mike1967]

Not practical (IMO) for diving unless you have a very specific depth level(s) plan and stick to it pretty exactly.

True, exactly the same using tables. Neither compare to using a computer.

 

[rhwestfall]

I'd never say "useless", but accept "less useful"...

 

[Nestor Wheelock]

19 mins but only after a diver has ensured that his tank was filled and inspected by someone that has been employed for over 90 days and signed a statement acknowledging that the air in his tank is in fact dangerous.

Do you have a liability waiver template you could share demonstrating this? In seriousness, I'm collecting them and sharing them where I live with my friend an attorney to stimulate discussion and analyze them and the potential for liability and risk.

 

[rhwestfall]

 

[boulderjohn]

That’s what I thought until I did some research earlier today. However, maybe someone can clarify PADI’s current definition.

What Tursiops said is exactly true when dealing with the RDP or the wheel. Your bottom time ends when you begin your direct ascent toward the surface (which may include a safety stop). There are no variations. That is critical when planning dives using the RDP or wheel. That is how you log your dives.

The problem is that very few people use tables for their diving, and those table computations in your log book are no longer necessary. Divers using computers on multi-level dives have struggled with how to deal with bottom time. Consequently, PADI has told them that for computer-based dives, they can pretty much do what they want, including surface to surface (which is what I do).

The rules for the RDP, however, have not changed.

 

[Scraps]

True, exactly the same using tables. Neither compare to using a computer.

I use the tables the same way I use my fingers as dividers when looking at a nautical chart: to give me ballpark approximations to keep in the back of my mind as further information and evidence presents itself.

Of course, my finger-dividers are more accurate and verifiable than the dive tables.

 

[boulderjohn]

I've seen one in use but it was useless since we descended to 120' and gradually ascended with no set time at any specific depth. I have an eRDPml--nice toy to practice on or fool around with. Not practical (IMO) for diving unless you have a very specific depth level(s) plan and stick to it pretty exactly.

If you are ascending at a regular pace, then it is not a multi-level dive, and there is no point in using the wheel.

Let's say instead you do the first 10 minutes of a dive between 80-100 feet and then ascend. For the next 7 minutes, you poke around between 60-70 feet. Then you go up and spend 20 minutes between 30-50 feet. Then you go up, do a safety stop, and surface.

When you are done, you would take out the wheel and calculate 10 minutes at 100 feet, 7 minutes at 70 feet, and 20 minutes at 50 feet, for a total of 37 minutes of bottom time.

 

[TMHeimer]

True, exactly the same using tables. Neither compare to using a computer.

Agree. RDP is fine for square profiles (which is about 98% of my dives, not that it matters). And you know that if you spend 5 minutes at 100' and the rest at 50' tables do you no good. But the eRDPml I believe is supposed to be something to use to plan multi-level dives. Useless if you are new to the site, or decide to deviate even a little from the plan because something is of interest at one of the planned depths. You'd have to stay in the "straight jacket" to make it work. Or, forget it and just follow your computer (which is what we did on that 120' dive I mentioned).

 

[tursiops]

That’s what I thought until I did some research earlier today. However, maybe someone can clarify PADI’s current definition.

?? What I said is almost a direct quote from PADI material. Here is the definition from the manual for the RDP.

Perhaps you are talking about today's ambiguity in BT? After all, a dive computer just tells you (typically) how long you spent below (typically) 5 ft or 1 or 2m. We often call that BT, even though it is longer than the traditional definition, but the definition for the RDP is clear.