New Divers -- I need your help...

[Randy43068]

Dayum, are the OW students these days STOOPID and unable to learn anything beyond "never hold your breath while under water?"

Peter, you're on the right track. As mentioned it needs a few tweaks here and there, but you have an excellent idea.

This is exactly the thing that the dumbed down OW course needs.

Good work Peter!!

 

[Windwalker]

I love the writeup. There are several questions that New Divers ask that are hard to find the answers for. I don't think the information is to advanced. I feel if your going to be diving, gas management should be beat into the students head from the beginning.. One of my dive partners who just got her cert thinks gas management is turning on the tanks before jumping into the water.

 

[aquaman_06]

Peter,

I found your table interesting. Is that something you did on your own or was that a requirement of your DM training? When I did my DM training we didn't have to do anything like this. I found it interesting and potentially useful. The problem is most OW certified divers don't even realize that you breathe more gas the deeper you are and this is likely to confuse them.

Sadly most OW instructors really don't touch on these issues and other then teaching you the recreational dive planner and how to judge pressure groups you don't get much training on how to judge air consumption. I think the table you have made is very useful I just don't know that many beginning divers will be able to make heads or tails of it.

That said: diving with people that run out of air before you could be a tricky and potentially dangerous scenario. Checking your air is obviously very important but so is dive planning and preparing for an unforeseen event. It's easy (especially the more you dive and more confident you become) when enjoying the tropical reef to make air consumption your second order of business.

**EDIT** I hadn't read JimLap's post. He is right about PADI's stance on DM's - personally I think it's a load of crap. PADI wants you to kneel at the bottom of the pool and maybe just maybe if a student is struggling to clear their mask or do a fin pivot (or is it pin fivot) you might get to assist them. I think PADI should A. Add a lot to their DM course first and B. give their DM's some power. I like the PADI system of diver training in that it makes diving accessable to most people in reasonable physical condition. Although I feel that when you start reaching pro level there are some things left out that are very important.

 

[Peter Guy]

Why I wrote this? Because I wanted to -- not an assignment, just an idea. I've had conversations with several instructors about the sad lack of any "gas management" in the curriculum. I also was a part of a "funny" discussion with an instructor during my "deep specialty" dive planning. I'm not at all sure he really understood the "rock bottom" concept nor was he really keen on discussing anticipated gas needs since he knew we "had all the gas we needed" and we'd just start coming up when we "got low" (or some such).

Anyway, this is my answer to that type of "planning."

I've thought a lot about the complexity of the first version, and thanks to all who commented on it. I've made another attempt to simplify it -- to give this a more "cookbook" approach. I still wanted to keep it at one page and so I've taken out a lot -- but I hope the gist remains.

Please take a look and comment further:

How Much Gas Do You Need For Your Dive? -- REVISED version 2

Blackwood -- Lynne (my wife) told me about your post and matrix as I was writing my revised version. She's already printed it out for reference. Thank you.

 

[sea nmf]

I think it is a swell idea! To those that say it is too much for new divers, I say that you might be correct.

However, the concept is what they need to buy into. Once that is done, the motivation is there to learn the method.

I dove years before I figured out that I was, in fact, doing this instinctually. Learning to formalize the process, particularly with new buddies, is great.

 

[gcbryan]

Why I wrote this? Because I wanted to -- not an assignment, just an idea. I've had conversations with several instructors about the sad lack of any "gas management" in the curriculum. I also was a part of a "funny" discussion with an instructor during my "deep specialty" dive planning. I'm not at all sure he really understood the "rock bottom" concept nor was he really keen on discussing anticipated gas needs since he knew we "had all the gas we needed" and we'd just start coming up when we "got low" (or some such).

Anyway, this is my answer to that type of "planning."

I've thought a lot about the complexity of the first version, and thanks to all who commented on it. I've made another attempt to simplify it -- to give this a more "cookbook" approach. I still wanted to keep it at one page and so I've taken out a lot -- but I hope the gist remains.

Please take a look and comment further:

How Much Gas Do You Need For Your Dive? -- REVISED version 2

Blackwood -- Lynne (my wife) told me about your post and matrix as I was writing my revised version. She's already printed it out for reference. Thank you.

Much better. I'd still get rid of the Ft3 references and replace with cu ft but that's just a small point.

 

[HenrikBP]

I'm a bit of a geek and also quite interested in knowing the why and how of things, so I really liked your paper. I would gladly have done a couple more classroom sessions in either OW or AOW to get information like this presented in an easily digestible fashion.

As it were, we were in OW introduced to the idea of using more air when going deeper, however the Deep dive of AOW was really just "we'll go to 100' and be back up shallow before we need to worry about air".

I have later been fortunate to come across good sources for that information (Thanks Bob and Lamont), but thanks Peter for your effort and for not "giving up" on us newbies, just 'cause the agency "says so"

Henrik

 

[jbmooney]

Peter, I think that's much clearer, though I think it leaves out some stuff I would have liked to be shown in the AOW class (if not in OW).

Blackwood, I recognize the technique, and have practiced it since I started to understand that I would need to know my SAC rate, even if it does improve over time (BTW, I came to know that here on SB, not in OW class where I should have learned it, in my view.) Peter's original discussion of SAC rate suggested determining average depth of dives over time, and if one is using that method, being careful about using the right averages is important, I think. Nice matrix, BTW.

I still think OW divers (or at least AOW students) should get some grounding in working out SAC rates over time, though this may not be the place to do it. I've taken to using changing SAC rate as one of the markers for how I'm progressing as a diver (so the fact that I haven't arrived at a fixed rate that will be useful for the indefinite future isn't troubling to me), and I think it's a useful exercise to begin thinking in these terms as early as possible (habits formed first last longest).

Steve R, I didn't intend to make you feel bad, and I'm sure you have good reasons for your disenchantment, but please understand that for those of us noobs trying to work our way out of the darkness, the lighting of candles is more useful than more knowledgeable people joining us in cursing the fact that it's dark.

 

[Blackwood]

Peter's original discussion of SAC rate suggested determining average depth of dives over time, and if one is using that method, being careful about using the right averages is important, I think. Nice matrix, BTW.

I don't recall Peter's suggestion, but I'm not sure what you mean by "the right averages."

If you note your beginning pressure and your ending pressure, the average depth of and all the gas you used during the entire dive is appropriate. If you note your pressure at bottom time minute 10 and again at bottom time minute 20, the average depth and gas used during those 10 minutes is appropriate.

I think you'll find that most people use the entire dive to determine SAC/SCR. However, doing so blurs together a variety of different rates. When you're descending, ascending, or just hanging on a stop, you won't be breathing as quickly as when you're swimming, for example. Using the entire dive as your dataset won't tell you that, and, as such, I prefer the later method. I like to know my resting rate (example: deco with no current), my working rates (example, leisurely swimming, swimming against a current), etc..


As for that matrix... that's not something I ever really reference because I know the numbers, and I encourage others to learn them as well (note, I'm not suggesting anyone memorize large matrices. Rather, know how much air you consume per minute, and be aware of your depth). If you know what you should see each time you look at your SPG (which you hopefully do at regular intervals), and if you see something drastically different than expected, something is wrong (you have a leak, or you're working extremely hard, or whatever) and you can make adjustments accordingly.

 

[FunkyDiver]

Peter, I like the fact that you took the time to try to get this on paper and get it out to people. I have seen a lot of posts mentioning gas planning, but have never really seen too much about how to actually do it (what do you mean use the search function-LOL).

I like the way gcbryan laid it out. It's formatted well and is presented logically with the examples spelled out well. It essentially walks a person through the problem so that he/she ends up with a solution that is easy to arrive at. If some of the other suggestions are incorporated such as changing "min gas" to "safety reserve" I think this could be a nice tool for people to use. I don't have a lot of dives under my belt, and I essentially come from the "check your gages often" school of gas planning.

I like this and will use it especially when I get some deeper dives planned.