Recommendations for AOW electives

[*Floater*]

*Floater*, you may or may not have been OK based on whether you were diving square profiles or multilevel profiles. Was that 21m for the whole 40 minutes? If not what was the profile like?

The first dive was to several wrecks that were between 18-21 meters. I recorded 20 as my max depth (though my Timex DM seems to round down the depth) and 46 min as my total dive time, so I was probably between 18-21 for about 35-40 min and the rest of the time was spent on descent, ascent and the 3 min safety stop. The second dive, had a max depth of 22 and it lasted 50 min. This second one wasn't a wreck, so my depth varied more during it, but diving conditions were similar and I spent 200 bar of air during each dive, so I must have been around the same depth for the majority of the second dive as for the first. I estimate that the average depth (not including descent/ascent) was probably 19m for the first dive and 17m for the second dive, and each lasted about 40 min (not including the ascent/descent).

Let me preface this by saying I'm not familiar with how liberal or conservative the SSI tables are compared to the PADI RDP. IIRC -- and someone check me on this -- to get multilevel credit on the PADI Wheel from a 21m (70') dive you'd have to do the second part of the profile at 15m (50') or less, and to get multilevel credit from 15m (50') you'd have to do the second part at 12m (40') or less. I don't know whether the SSI tables even allow for multilevel dive profiles?

They are conservative in the sense that one is supposed to use the max depth for the dive rounded up to the nearest multiple of 3 multiplied by the time from beginning of descent to the beginning of ascent. So if there's any multilevel element to the dive, then the tables are inaccurate, and also I prefer to round everything down.

However I did a dive to another wreck at 30m (max depth reached was 30.7), though my average depth was probably around 28.5m, and the dive time (includeding ascent and descent - which took about 6min with the safety stop) was 30 min. The dive master and I were both wearing an Aladin Pro and began the ascent when the alarms went off to tell us that the deco count had reached zero. According to the SSI table, the no-deco limit for 30m is 20 min, so it's about the same as the Aladin if you happen to be close to the limits used in the table. The conservatism mainly comes from the usual round off error that's usually present.

The main difference in opinion appears to come from the amount of time it takes to recover for another dive. I'm not sure the SSI tables take into account the safety stop, plus all the rounding up make the estimates overly conservative. The dive resorts may prefer to offer 3 full dives a day (full=180-200 bars of air used) because they make more money that way, but I also haven't experienced any readily observable negative effects from doing things their way.

You don't necessarily need to take the PADI multilevel class to understand the Wheel and how to plan multilevel dives (whatever you do don't buy the video!). In fact, the book for the specialty class is a little long in the tooth and can actually be hard to come by. But depending on what you wanted to cover in your AOW, if it helps you to really understand how computers give you extra time then it might be worth it to you. See if your instructor wouldn't loan you his Wheel for the class (its required for PADI DMs and instructors so they'll have one laying around), then laminate a copy of Charlie99's Flat Wheel after you understand how it works.

IMO, whatever you do take a good nitrox class (not part of the AOW) if you are going do repetitive dives like 21m for 40 minutes.

I read here on scubaboard that for multilevel dives I can just use the SSI or PADI tables the way I would use them for a repetitive dive, except to use 0 as the surface interval between each level change. I think most of the error from the tables comes from rounding everything up, but even then they are a little too conservative.

I'll asked about a nitrox class next Christmas when I go back to the Philippines to visit my parents.

 

[*Floater*]

Have you considered Fish ID? I loved mine...saw some HUGE (2ft diam) crabs and such, but no scorpion fish (turns out, there wasn't one there)

I actually ended up taking that elective. It was a good choice because I read the chapters on Fish ID and Underwater Naturalist and then just went for a dive and took a bunch of photos. I enjoy u/w photography so fish id was the right thing for me.

On another matter, I have now thought more about what I should have done as a student during the course, and here are a few things I wish I had done, and which I recommend for others considering the AOW. (Also, I was was the only student & diver at that resort, so my instruction was fully personalized, plus the instructor was very experienced):

1. I wish I had asked him to have me plan all the dives. We should have done navigation first, and then I would tried to plan the dives and navigate during them.

2. I wish I had asked him to brush up my emergergy skills. We could have done several emergency ascents and simulated a few emergency situations underwater. Also, I should have asked for his tips on equipment inspection pre-dive, and info on potential equipment failure scenarios.

3. I wish I had forgone a few dives when conditions weren't optimal. During one time the current was so heavy, that we didn't make it to our intended desination (shark cave). He told me the current was hard before we descended (during the deep dive), but I wanted to go anyway because I had a pair of new Tusa x-pert zoom split fins, and I wanted to see if the talk about them sucking in a current was true. It wasn't (though I have some theories about that), but my air got used up in about 15 min because I had to swim against a strong current whilst learning to use my new equipment.

4. I wish I had done the night dive. They cost 50% extra at the resort I was stay at, so I could got $8 more worth of diving out of the course had I done it.

I'm sure there are other things I should have asked, but that's all I can think of for now.

 

[TSandM]

Floater, I totally agree with you about the dive planning. From reading this board, I have realized I really don't know how to do it, and I plan, when I get back from Maui (yay!), to make sure that as I pursue more electives, I get more active in the planning and the navigation. It's too easy just to follow somebody else!

Having just done my night dive, I can recommend that, too -- a very different experience, and one which can tell you if your coping skills underwater are marginal, for sure.

 

[Dutchman]

Flyguy, you said:
FYI, the dives my group did are as follows:
Deep
Navigation
Peek performance
Wreck
Boat
Night
Drift

It was a busy weekend starting Friday night and going all through Saturday and Sunday.

My question, how can you do all this in two days and really learn anything. I am thinking about AOW but would not be able to do all that in 3 days.

 

[StSomewhere]

I read here on scubaboard that for multilevel dives I can just use the SSI or PADI tables the way I would use them for a repetitive dive, except to use 0 as the surface interval between each level change. I think most of the error from the tables comes from rounding everything up, but even then they are a little too conservative.

That doesn't quite work but its close. It might be worth going back to this thread and reread the criteria for the multilevel calculations. Its very important to remember that you can do the zero SI only under two conditions. 1) You need to ascend a certain amount before it counts as multilevel. 2) The NDL for the ML (second) interval is approx 85% of the normal NDL, as documented in Charlie's flat wheel.

That additional 15% can have you overstaying your NDL without realizing it.