Any danger from several shallow dives in a row?

[Jarrett]

Complete newbie here. I am diving with my 10 year old daughter. We both just got PADI OW certified a few weeks ago in Cozumel. Now back in Texas and went for our first lake dive yesterday. I went into it thinking about the dive from a PADI RDP standpoint, 30 feet, X time, etc., but that's not how it ended up going. The low visability kind of worried my daughter and she wanted to come up often. So it kind of went like this:

Down to 18 feet for 10 minutes and back to surface.
Wait a couple of minutes and down to 28 feet for 3 minutes and back to the surface
Wait two minutes and down to 15 feet for 20 minutes and back to the surface.
Continuing along those lines all day. The most we had on our nitrogen bar on our computers were 2 bars at any one point (Aeris Atmos AI)

As far as I know, the PADI RDP starts at 30 feet and assumes that you will be there for a specfic amount of time with a relative surface interval following. Our dives didn't go in that format.

My initial question: Is that type of diving safe until my daughter gets comfortable enough to stay down for a whole tank?

Also, our first ascent from 28 feet, we went faster than the standard 30 feet/minute pace. I forgot to track it via my dive computer as we ascended. I heard my computer going off, but it didn't register at the time. How bad was that?

Any info would be greatly appreciated, thanks in advance!

 

[ScubaThor]

Any dive above 30 feet should still be considered a 30ft dive....remember, those tables round up.

 

[MXGratefulDiver]

Complete newbie here. I am diving with my 10 year old daughter. We both just got PADI OW certified a few weeks ago in Cozumel. Now back in Texas and went for our first lake dive yesterday. I went into it thinking about the dive from a PADI RDP standpoint, 30 feet, X time, etc., but that's not how it ended up going. The low visability kind of worried my daughter and she wanted to come up often. So it kind of went like this:

Down to 18 feet for 10 minutes and back to surface.
Wait a couple of minutes and down to 28 feet for 3 minutes and back to the surface
Wait two minutes and down to 15 feet for 20 minutes and back to the surface.
Continuing along those lines all day. The most we had on our nitrogen bar on our computers were 2 bars at any one point (Aeris Atmos AI)

As far as I know, the PADI RDP starts at 30 feet and assumes that you will be there for a specfic amount of time with a relative surface interval following. Our dives didn't go in that format.

My initial question: Is that type of diving safe until my daughter gets comfortable enough to stay down for a whole tank?

Also, our first ascent from 28 feet, we went faster than the standard 30 feet/minute pace. I forgot to track it via my dive computer as we ascended. I heard my computer going off, but it didn't register at the time. How bad was that?

Any info would be greatly appreciated, thanks in advance!

Multiple ups and downs, with very short stops like you describe, are not generally good for your body. This is true even when depths are relatively shallow. You are still putting your body under pressure, and absorbing nitrogen into your tissues beyond what you would normally be exposed to at surface pressures. Then you are taking that nitrogen out of solution by surfacing ... and forming bubbles if you're doing it too quickly ... then not giving your body time to offgas before going back down and doing it again.

While at those depths and times you are not absorbing a lot of nitrogen compared to divers who go deep and stay long, you are still putting yourself in a situation where those tiny little bubbles might start to merge, and eventually cause a DCS hit.

My recommendation ... 1) If you must come up, concentrate on coming up very slowly ... certainly no faster than 30 feet per minute, slower if you can manage it. and 2) Remember what you learned in OW class ... a minimum safe interval between dives is 10 minutes (required), and a recommended safe interval is one hour. If she's not comfortable, take the time to talk about what you experienced during that short time underwater, what you learned, and what you want to work on during the next "dive". That should get you through the 10-minute requirement.

... Bob (Grateful Diver)

 

[spectrum]

Complete newbie here. I am diving with my 10 year old daughter. We both just got PADI OW certified a few weeks ago in Cozumel. Now back in Texas and went for our first lake dive yesterday. I went into it thinking about the dive from a PADI RDP standpoint, 30 feet, X time, etc., but that's not how it ended up going. The low visability kind of worried my daughter and she wanted to come up often. So it kind of went like this:

Down to 18 feet for 10 minutes and back to surface.
Wait a couple of minutes and down to 28 feet for 3 minutes and back to the surface
Wait two minutes and down to 15 feet for 20 minutes and back to the surface.
Continuing along those lines all day. The most we had on our nitrogen bar on our computers were 2 bars at any one point (Aeris Atmos AI)

As far as I know, the PADI RDP starts at 30 feet and assumes that you will be there for a specfic amount of time with a relative surface interval following. Our dives didn't go in that format.

My initial question: Is that type of diving safe until my daughter gets comfortable enough to stay down for a whole tank?

Also, our first ascent from 28 feet, we went faster than the standard 30 feet/minute pace. I forgot to track it via my dive computer as we ascended. I heard my computer going off, but it didn't register at the time. How bad was that?

Any info would be greatly appreciated, thanks in advance!

Well it's good practice on clearing ears and ascent / descent. We have shore dives where the topography drives profiles that aren't that different. I to am interested to hear the replies from the deco wonks. You're correct that from an NDL standpoint you're way in the clear but there are some penalties associated with a sawtooth profile. Again at those depths I don't know if there's an issue there either.

As for the computer being missed on ascent that's a red flad. IMO at this point in your dive history that's probably the most useful function the thing has so both of you should zero in on it.

Pete

 

[Day]

(In my opinion 10 years old is little bit young anyway. I suppose it all depends on the child's ability and acts of responsibility. Several agencies certified at that age so it must be safe. However, this is a subject for a different discussion.)

My dad took me diving very young so my words of advice are don't push her and let her take her time. If she is scared and has a bad experience she may never want to dive again. That being said, I think the biggest danger of ascending and descending repetitively will be ear squeeze/eardrum trauma.

 

[Jarrett]

Thanks for the info so far, I really appreciate it. The "sawtooth" profile that you were talking about is definitely what I am concerned about. For some reason, either I missed it or wasn't taught it, I didn't know about 10 minute minimum interval. I do now, thanks. And definitely not watching our ascent rate was my fault. It only happened on our first dive and we watched it carefully for the rest. It's one mistake I won't make again. Thanks again and I'd love to hear more input on our mistakes and repercussions here.

 

[Rec Diver]

Running out of air would be dangerous!

 

[Jarrett]

Running out of air would be dangerous!

Hehe, yeah we kept a close eye on that one. I was more concerned about issues that weren't so obvious such as some weird buildup of nitrogen that could cause DCS or lung injury due to the ups and downs. Things of that nature.

 

[Heffey]

I am also interested in the replies here as a noobe.

My understanding is that a second dive with a SI shorter than 5 min is considered a continuation of the first dive.

Also, excluding the quick assent rates, how are these dives any different than, say following the contour of a reef where a 20ft or 30ft variation in depth would leave you with a bit of a rollercoaster profile.

I very well may be wrong but, my understanding at this point tells me that as long as I am using proper accent rates and counting all of the little short dives as a single dive there should be no big issue especially at that shallow depth.

I,m here to learn so fire away
Jeffrey

 

[*Floater*]

A DM at a resort I was staying at earlier this summer said he got DCS from doing the type of diving you describe (except maybe with faster ups and downs) while trying to help a new student to descend. I was there about a month after the fact and he still couldn't dive. He may never be able to dive again. He told that's how it often happens because you don't expect it.