Reverse Profile dives in AOW

[hockeyplay]

Hello all.

I am new to Diving having gotten just 7 dives under my belt and my PADI OW cert. This weekend I am slated to take an AOW course as the PADI types won't let me work toward rescue without it.

The Instructor has planned 4 dives for Sat. The first at 100', the second at 30', an SI of about 3 hours, then a 60' and another 30'.

Having very little experience as yet, I have some trepidation about making a reverse profile reperitive dive set, even with the SI.

With all the conflicting info on reverse profile dives and effects on NDL's, I wonder: Am I being paranoid or is this an unneccessarily risky day of diving?

Any advice or info is GREATLY appreciated.

 

[fins wake]

The Instructor has planned 4 dives for Sat. The first at 100', the second at 30', an SI of about 3 hours, then a 60' and another 30'. Having very little experience as yet, I have some trepidation about making a reverse profile reperitive dive set, even with the SI.

If you trawl this board you'll find many comments on repetitive dives and reverse profiles. BRW is one of the guys here who've written the best points on the consensus as regards the latter. (You'll find that a 30' feet reverse profile fits into this consensus, but your dives are part of a four-dive series, which adds another level of complexity.)

The only thing that draws my attention is the fact that you're doing 4 course dives in one day. To me - privately - that seems somewhat excessive by any standards. Many AOW courses split up e.g. 5 dives as 3+2 over two days, and often with proper surface intervals. What is the interval between dive 1 (100') and dive 2 (30') and between dive 3 (60') and dive 4 (30')? You don't mention these.

The surface interval between dives 2 and 3 seems fine to me, it's more the other ones I'm thinking of.

I guess your instructor has decided on deep dive, navigation dive, "something dive" and then a night dive - which is all perfectly feasible -and plenty of people including myself do multiple repetitive dives like these (albeit deeper) sometimes, e.g. on liveaboards. Yours are course dives, though ...

 

[hockeyplay]

Thanks. I don't have the info on the SI between the 100' and 30 and 60' and 30', but I assume they are likely sufficient to keep us somewhere within groups N-R ( I know, it's a heck of a span). Actually the first is a wreck dive and the second a reef. Based on the geography I am guessing an SI of 45 to an hour between the 100' and the 30'.

 

[Arnaud]

Unless PADI has changed their standards very recently, an instructor cannot teach more than 3 training dive a day (to the same group).

 

[hockeyplay]

The fouth dive is supposed to be a just a fun, relax dive after the days coursework. I don't believe any training is going to occur on that one.

I am more concerned with the profile, but if that's not an issue than I'll stop whining and get back to blowing little bubbles....

 

[Arnaud]

You shouldn't hesitate to discuss your concern with your instructor. Most likely, with a 3 hour SI, you should be OK. But you'll know for sure at the end of the SI following your second dive.

 

[BlueDevil]

As I understand it the general consensus is that reverse profile dives are now regarded as being ok provided the dives are within the recreational limit(40m or 130ft) and the difference between the two dives is no more than 12m (40ft).

However I would have some concerns about the series of 4 dives that are planned, it seems a bit excessive to me in one day.

 

[Arnaud]

...However I would have some concerns about the series of 4 dives that are planned, it seems a bit excessive to me in one day.

Nah. Excessive is 6 dive a day in cold water with a wetsuit on air and 30 minute SI's...

 

[theskull]

Sounds like a very reasonable and conservative group of dives to me. A perfect example of just 1 day out of a several-day-long live-aboard dive trip.

theskull

 

[Diver0001]

Hello all.

I am new to Diving having gotten just 7 dives under my belt and my PADI OW cert. This weekend I am slated to take an AOW course as the PADI types won't let me work toward rescue without it.

The Instructor has planned 4 dives for Sat. The first at 100', the second at 30', an SI of about 3 hours, then a 60' and another 30'.

Having very little experience as yet, I have some trepidation about making a reverse profile reperitive dive set, even with the SI.

With all the conflicting info on reverse profile dives and effects on NDL's, I wonder: Am I being paranoid or is this an unneccessarily risky day of diving?

Any advice or info is GREATLY appreciated.

I wouldn't personally be too concerned with that set of dives assuming that the bottom times are not excessive. The 3 hour SI is good and you should concentrate on making a nice slow ascent from the 100ft dive. If it were me I would judge whether or not to make the 60ft dive based more on my ascent from the 100 ft dive than on the depth alone.

Having said that, there is some evidence to suggest that reverse profiles where one dive is 40+ft (IIRC - do a search on "Weinke" and "reverse profile") deeper than the previous dive carries a slightly elevated risk of DCS. You're not going over the 40ft mark so once again I wouldn't be too concerned.

R..