Quiz - Recreational Dive Planner™ - Max Time

[boulderjohn]

It would be surprising to find RDP questions on a DM exam, being that this is (was....) OW course stuff.

DMs are expected to be able to assist with instruction, and if the students in a class are learning to use the tables, the DM might have to help.

 

[scubadada]

Well, IME ascending slowly from the SS isn't as hard as being able to stop at SS depth when you've been ascending from the bottom to the SS at 10-18 m/min (33-60 fpm).

When I did those exercises, we were allowed to stop at ~9m and ascend slowly from that depth to the SS/shallow deco stop. It gave us a bit of a margin. I'm not certain I'd be able to ascend at 18 m/min from, say 30m/100' to 3-5m/10-15' and then make the stop.

Back in the day, I did most of my ascent vertically. Doing in horizontally really slowed me down and gave me much better control.

 

[tursiops]

I routinely used the RDP for multilevel dives where there were two well defined levels and a few times for a three level dive.

See https://www.scubaboard.com/communit...e-padi-rdp-table-for-multi-level-dives.595203 for why this is an incorrect and possibly dangerous procedure, even though lots of people do it.

United Technologies Corporation had a poster many years ago that said:

"If 50,000 people believe in a dumb idea, it is still a dumb idea."​

 

[boulderjohn]

See https://www.scubaboard.com/communit...e-padi-rdp-table-for-multi-level-dives.595203 for why this is an incorrect and possibly dangerous procedure, even though lots of people do it.

United Technologies Corporation had a poster many years ago that said:

"If 50,000 people believe in a dumb idea, it is still a dumb idea."​

Remember that measuring multi-level dives was a primary goal of the RDP research from the very start. If this method worked with the RDP, there would not have been any point in making the wheel.

 

[TMHeimer]

DMs are expected to be able to assist with instruction, and if the students in a class are learning to use the tables, the DM might have to help.

Oh agree of course. I was just surpised to read that RDP questions were on the DM test. Was thinking this:
For me, it was a big part of the OW course and test, so why would it be reviewed in the DM course and on that test? Other things such as really basic equipment stuff (ie. What is an O ring?), other really basic dive stuff, wasn't on the DM test(s) I took.
--But maybe there is now a call for RDP review at the DM level because many (most?) current DMTs were not taught tables in OW?

 

[BlueTrin]

SurfGF on a computer is a game changer for me. I keep my computers in tech mode, so I don't get any sort of safety stop countdown the way most divers do. When I am doing NDL dives with friends using recreational computers, I watch them counting down the safety stop to the precise second they are allowed to ascend. Meanwhile, I have looked at my SurfGF, and if I like what I see there, I am good to go up whenever they are. I did a number of dives in the 50-60 foot range for an hour each on EANx 36 this winter, and when I reached the SS level with my buddies, my SurfGF was usually between 43-50, well below what I would have been happy surfacing with after deeper dives. My buddies were doing the same dives with the same mix, so I assume their would have been the same if they had had a computer to show that, but we all waited until their computers counted down that magic 3 minutes.

Here's the problem--what makes your ascent more conservative? There is no question that the lower the SurfGF the better, but what is more conservative BEFORE you reach that stop? My question is genuine. After researching it, I don't know. As some of you know, I got bent last year after a two tank recreational dive that should have been ultra safe. That was before I did my research. Now that I have completed my research, I do everything the way I did before, because I have no idea what to do to make it safer, other than wait out the SurfGF to something ridiculous.

I understand the concept of surfGF: the gradient factor you would have if you surfaced now.

But how do people manage this during an actual dive ?

Do you try to stay longer to bring it down on the last stop for example ?

Is it more useful than extra time against your schedule because it is measured in GF ?

 

[tursiops]

Remember that measuring multi-level dives was a primary goal of the RDP research from the very start. If this method worked with the RDP, there would not have been any point in making the wheel.

This method came out AFTER the Wheel, and used it for verification.

 

[boulderjohn]

Oh agree of course. I was just surpised to read that RDP questions were on the DM test. Was thinking this:
For me, it was a big part of the OW course and test, so why would it be reviewed in the DM course and on that test? Other things such as really basic equipment stuff (ie. What is an O ring?), other really basic dive stuff, wasn't on the DM test(s) I took.
--But maybe there is now a call for RDP review at the DM level because many (most?) current DMTs were not taught tables in OW?

I would bet 99% of people who were taught how to do tables in their OW classes could not do them now.

 

[scubadada]

I understand the concept of surfGF: the gradient factor you would have if you surfaced now.

But how do people manage this during an actual dive ?

Do you try to stay longer to bring it down on the last stop for example ?

Is it more useful than extra time against your schedule because it is measured in GF ?

Yes, that is correct, you stay at your safety stop or last deco stop level until the SurfGF is within the range you are targeting.

 

[boulderjohn]

This method came out AFTER the Wheel, and used it for verification.

I am not sure what you mean by this. I need a little more information to fill in my blanks.

According to The DSAT Recreational Dive Planner: Development and validation of no-stop decompression procedures for recreational diving. (February 28 1994), by R.W. Hamilton, Raymond E. Rogers, Michael R. Powell, and Richard D. Vann, multi-level diving was a primary goal for the RDP research from the start.