Diving at or above 60 feet

[Carribeandiver]

This cannot be a serious question, can it?

 

[LeadTurn_SD]

I don't have my PADI book with me and I could be wrong but shouldn't you ascend slower from a greater depth (i.e. 30 fpm below 60 feet) than a shallower depth (i.e. 60 fpm above 60 feet)?

Short answer: No. Just the opposite.

Longer Answer: The greatest rate of pressure change occurs in the last 30 feet. That is where you really need to have your ascent rate under control. 30 feet per minute is what is now recommended by most, 60 feet per minute max (PADI still teaches 60'/min I believe). The safety stop is optional if within NDL, but highly recommended. At deeper depths, you are still "on-gassing", so generally a faster ascent (60 feet per minute) is used.

 

[krbailey]

LDTurn_SD

Thanks for the info. I need to spend less time at work and more time with my PADI book!

 

[seaducer]

If your diving t or above 60 feet. What is the normal protocal for surfaceing. Do you come up slow or stop every so many feet. Or at or above 60 does it matter.

The "normal protocal", well, there really isn't one. If you are planning and executing dives on tables, the table itself will tell you how best to ascend.

For example an NDL dive to 60 feet calls for ascending no faster than 60 feet per minute to 15 feet, where you hold a stop for 3 minutes, then continue to the surface, according to my PADI RDP.

Most divers, agencies, and other groups that I am aware of recommend a 30FPM ascent, holding a stop between 10 and 20 feet for 3-5 minutes.

Bear in mind that each dive planning algorythm, be it a table, software, or computer may be calculated on a different ascent procedure. There is no "correct" way, only the way your planner was designed, and a really unsafe one, like shooting up like the sub in Hunt for Red OCtober. In order to minimize your exposure to DCS using a computer, you should follow that guide as opposed to whatever you learn in class. For example, my RDP from PADI is new, they still print 60 FPM, but if I dive using my computer, the software is calculating my NDL based on a different ascent rate.

For any NDL dive, these should be considered no stop dives. While it is good practice, theory, and safe to always do a safety stop, it is not required. The NDL times are calculated to reduce your risk for a direct ascent. So do not feel you have to make a safety stop, if you are uncomfortable you should be safe to ascend and exit the water.

Your class will likely go over this in more detail as it pertains to whatever planner they use. And remember, diving even within the limits of your table, and ascending according to that protocal, your risk of DCS is not eliminated, only minimized.

 

[seaducer]

This cannot be a serious question, can it?

Indeed. Remember we are in the New Diver forum. The bio on the OP says he isn't certified, so I can assume he is in, or signed up for a class. This is quite a reasonable question for a new diver considering all the different planners and recommendations out there. And if he has his hands on a PADI RDP and a new computer his head may be spinning.

 

[rstofer]

I don't have my PADI book with me and I could be wrong but shouldn't you ascend slower from a greater depth (i.e. 30 fpm below 60 feet) than a shallower depth (i.e. 60 fpm above 60 feet)?

You should think about this in terms of percent of pressure change versus ascent time. You change pressure by 100% in the last 33 feet to the surface. You also change pressure by 100% between 99 feet and 33 feet. You would be making these 100% changes in the same time interval if you ascended at 60 fpm between 99 feet and 33 feet and 30 fpm between 33 feet and the surface.

If you are uncertain about any of this, you should review your training manual. It's always a good idea to go back and reread these sections.

Ascending at 30 fpm and a safety stop at 15 feet for 3 minutes is highly recommended!

Richard

 

[bigtim6656]

I will not take my class till march i was just trying to get some of the stuff out of the way to make the testing and book stuff easyer

What are they teaching you in class???.... the answer to your question is very straight forward ie think of the word s-l-o-w--unless you're late for a very important date.........

 

[tfsails]

Lemme see if I can remember my basic PADI OW instructions:

Slowly
Ascend
From
Every

Dive.

I had that drilled into me from the get-go. It's good advice!

 

[CamG]

Greetings bigtim, it is great to hear your question and it has been answered very well.
If your signed up for March it would be a good idea to get started on your academics "book work" early. That way by the time you actually get to class you will have covered the material several times. I have found repetition really helps as well as quizzing with your buddy. It can be fun and in the process the important facts get memorized. It is not rocket science type of material so it is pretty interesting especially if you watch the DVD also.
Have fun and keep up the research, SB is a great place to learn!
CamG Keep diving....keep training....keep learning!