Repeated ascents to surface during practising

[IrishPaul]

Hi all,

I want to work on my buoyancy, controlled ascents and skills such as SMB deployment.

What precautions should I take if making repeated ascents from say 20 feet to the surface?

While diving yesterday (with a borrowed rig) I was getting task loaded, and for example forgot some of the basics as raising my right arm over my head during the ascent.

I wish to practice safe, controlled ascents several times during my next dive - I will basically hanging around the float line and going up and down!

Thanks
Paul.

[spectrum]

I would not make this a concentrated effort. I all likelihood you will end the outing profoundly tired, or worse. Once or twice concentrating on excellence everytime you go out is a much better way to go. Alternatively mess around from 6-8 feet a few more times. Overdoing this can result in what some consider sub clinical DCS.

Pete

[TMHeimer]

I do a lot of shore shallow diving (age 58)--usually between 10-30'. Sometimes I ascend to check my distance from shore if the tidal current picks up. I tend to do this more when in the 10 foot range, as it only takes a few seconds and you know exactly where you are. No problems yet. I don't do any of this to practise skills, though the odd time I do practise a CESA when I'm ending the dive anyway. Being in very shallow water in itself is good buoyancy practise. If you can hover/swim 3' below the surface without popping up your buoyancy is pretty good.

[gcbryan]

All the bad stuff in diving happens on the trip back to the surface. I'd try to incorporate most of that practice at the end of the dive (not going up and down however) as it naturally occurs.

As was mentioned otherwise it's best to do it in 10 feet or less IMO. I never found the need to do this (everyone is different however). I much prefer to "practice" things as they naturally occur during the dive.

[Hatul]

You need to watch out for boats and keep your lungs open to prevent overexpansion injury.

[Jeff Pack]

Its no big deal as long as you ascend properly. I've taken private classes working on buoyancy that have repeatedly done ascents/descents for practice. In BUDS, we used to do it from 15-20ft for hours on end, and that was without scuba gear. Free Divers do it regularly as well.

[turnerjd]

There is no real problem doing a few (3 or 4) trips up and down a line in shallow water (<10m) to practice.

If you think back to OW dive 5 when you had to demonstrate 1:1 with the instructor the different ascents, the poor instructor must have done about 8 or 9 ascents in about 15 minutes.

If you are worried, get a tank of the strongest EANx that you can (<10m so get 40%) and do the ascents with this and the risk is even lower.

Practicing ascents is a very good idea, as gcbryan said, thisis where a lot of the problems happen

Jon

[NWGratefulDiver]

Frankly, you're going to have more concerns about what repeated pressure changes are doing to your ears and sinuses. I've been teaching skills workshops lately that involve repetitive ascents/descents in the 20-foot range. I've done six of these dives in the past four days, each dive involving 3 to 5 ascents to practice buoyancy control, or practice using a spool and bag, or ascending while sharing air ... and then discussing what we did, what I saw, what I want the student to do next ... and then re-descending to work on it.

In shallow water, nitrogen buildup isn't much of a concern ... repeated pressure changes in your air spaces will be. The best way to cope with it is to pressurize frequently on the way down, and ascend slowly on the way up ... much less than 30 fpm if you can manage it.

... Bob (Grateful Diver)

[turnerjd]

Frankly, you're going to have more concerns about what repeated pressure changes are doing to your ears and sinuses. I've been teaching skills workshops lately that involve repetitive ascents/descents in the 20-foot range. I've done six of these dives in the past four days, each dive involving 3 to 5 ascents to practice buoyancy control, or practice using a spool and bag, or ascending while sharing air ... and then discussing what we did, what I saw, what I want the student to do next ... and then re-descending to work on it

That is something I almost never think about, I think that over the last 16 years I have only lost one or two dives to poor ears, and for most of the time, never have the slightest problem with them.

Jon

[GrumpyOldGuy]

Side note: You might consider practicing and implementing SMB deployment from deeper than a 15-20 S/S depth. In the ocean, between worrying about boats zipping overhead and swells, just holding the stop can be a hand full. I choose to deploy the SMB closer to a deep stop depth (50' or so) when buoyancy control is easier and not so critical. Plus the act of slowly winding up the line on a thumb spool make a great pace setting to a proper ascent.

[Teller]

Remember the greatest pressure difference is in the shallower depths. That being said if your whole dive is going to be repeated decents and ascents to 20 feet then you shouldnt on gas very much inert gas.

[Splitlip]

Its no big deal as long as you ascend properly. I've taken private classes working on buoyancy that have repeatedly done ascents/descents for practice. In BUDS, we used to do it from 15-20ft for hours on end, and that was without scuba gear. Free Divers do it regularly as well.
Free divers aren't breathing compressed gas however.

[Quero]

If you think back to OW dive 5 when you had to demonstrate 1:1 with the instructor the different ascents, the poor instructor must have done about 8 or 9 ascents in about 15 minutes.

The ascents aren't as much a problem as the descents are. It causes my ears to get tender to do repeated descents over a short period.

[dwhthediver]

I would recommend stops at various depths on your ascent rather than multiple ascents and descents. Stop at 20' and hold it for a minute, ascend to 15' and hold it for a minute, ascend to 10' and hold it for a minute, and again at 5'. That will help your buoyancy as well as controlling your ascent. I teach this when I teach peak performance buoyancy.

[supergaijin]

Hi all,

I want to work on my buoyancy, controlled ascents and skills such as SMB deployment.

What precautions should I take if making repeated ascents from say 20 feet to the surface?

While diving yesterday (with a borrowed rig) I was getting task loaded, and for example forgot some of the basics as raising my right arm over my head during the ascent.

I wish to practice safe, controlled ascents several times during my next dive - I will basically hanging around the float line and going up and down!

Thanks
Paul.


If the whole dive consists of just doing ascents from that depth, you don't have to worry about Nitrogen, but as some posters wrote- do check your ear frequently and don't get caught in the trap that many instructors (myself included) do- in that they're surfacing and then descending before the ears have had time to recover and it's easy to get down say 10ft and then not be able to equalise.

It's not sometimes painful but if you try to equalise you'll probably hear a squeak in the ear and potentially a crack when air goes rushing in to the middle ear. It can be damn painful and often leads to infection.

I recommend people practice ascents and descents especially when they're starting out but do be careful and don't get too impatient with ears or it'll potentially ruin your day(s).

[TSandM]

You know, the theory says you won't absorb enough nitrogen to worry about, if you stay that shallow. But I will tell you my story. When I was a fairly new diver, I was working with a friend on controlled ascents and stops, and bag shooting. We went out on a night dive to practice -- well, controlling ascents at night can be challenging, since you don't have a light gradient in the water to help you orient, and both of us lost control of our ascents a couple of times. We must have done seven or eight, never deeper than about 25 feet.

I left the dive site about 8:30, which wasn't late at all. On the way home, I felt like I was back in my residency, when I sometimes went three straight days without more than an hour or two of sleep. I couldn't keep my eyes open, and my foot would slip off the clutch at stop signs. I was bone-deep exhausted, in a way that nothing in the past few days could possibly have justified.

I have never done that again. I am totally convinced that that exhaustion was decompression stress -- and several years later, when I watched the "Mysterious Malady" DVD, I was amazed to hear Dr. David Doolette say, on the DVD, that he feels that profound fatigue is a manifestation of "subclinical DCS".

I would advise against making repeated ascents, even from shallow water. Most of the instructors I know who do the day with the CESAs will admit that they feel pretty beat up that evening.

[turnerjd]

I have never done that again. I am totally convinced that that exhaustion was decompression stress -- and several years later, when I watched the "Mysterious Malady" DVD, I was amazed to hear Dr. David Doolette say, on the DVD, that he feels that profound fatigue is a manifestation of "subclinical DCS".

I would advise against making repeated ascents, even from shallow water. Most of the instructors I know who do the day with the CESAs will admit that they feel pretty beat up that evening.

I have to agree, my comment about EANx 40 was not based on any science, but my observation of instructors that have done multiple ascents, and how it affects them. Several instructors I know now swear by EANx 40 for this OW dive.

I will have to get a copy of the 'mysterious malady' DVD.

Jon

[supergaijin]

We went out on a night dive to practice -- well, controlling ascents at night can be challenging, since you don't have a light gradient in the water to help you orient, and both of us lost control of our ascents a couple of times.

To the OP....
I wouldn't recommend doing any new exercises at night.
If you're losing control, then you should stop and evaluate what you're doing.
Using a buoy line is one way to arrest your ascent if you start to go up to fast.
Don't ascend faster than your smallest bubbles.
Drink plenty of water.
Plenty of rest.
I think it's fair to say that if you're sensible in the way you practice these skills, not over-doing anything and not getting too impatient if your ears are playing up, you should be fine.

While it's hard to argue with a doctor, I can only say from my personal experience that I don't get any more tired when practicing CESA's with students but I do try to limit the ascents, I try to do them as first exercises of the day, and if I have a big group I will do CESA's with half on one day and half the next. To me that makes sense to limit my exposure to ascents as I'm working and exposing myself pretty much everyday.

[DivemasterDennis]

Practicing CONTROLLED ascents is worth while. The tips noted above for minimizing problems are good ones. I want to add that nitrogen absorption is not the issue in this type of exercise that lung expansion injuries are. If you are practicing controlled ascents, make them even slower than 30 feet/minute. Hover often, do it with a buddy, and have fun as you improve your skills. I have had training days where it seems I have been up and down from 35 feet and shallower as many as 8 times over the course of several hours, sometime more. I take the ascents and descents very slowly. My "up-downs" are for placing training platforms and navigation lines, accompanying different classes and their instructors, retrieving dropped gear, escorting students on tours,and sometime escorting distressed students to the surface. Be cautious, be conservative, especially as to ascent rate, and you will be fine.
DivemasterDennis