Best techniques for Open Water Descent & Ascent

[knowone]

A bunch I have watched over a period sometimes crash into the bottom to see who can make the biggest cloud of dust. At other times they race to the bottom and stop as closely to it without making dust. Closest person, least dust wins. During the dives they would calmly follow the contours of anything they were diving and not crash into stuff at all. These folks used to bumble around like lots of others, but with practice over not a great period of time ear clearing and bouyancy they seem to have become proficient at. And some of these were some real bumblers and stumblers. Sometimes you can't choose who else is on the boat. Or the internet.

 

[*dave*]

Nuff said on weighting, I think.

Given your experience level, I'd recommend starting out doing your ascents and descents vertically. Being vertical facilitates the dumping of gas from your BC to counter positive buoyancy and finning to counter negative buoyancy. For new divers, this can be much easier initially, than attempting a horizontal ascent before they have a solid handle on buoyancy control.

Ideally, you want to be able to arrest ascent or descent with your breath. If that's not possible, you need to add or dump gas from your BC. It takes some time to get the feel for how much to add or dump, so it's common for new divers to over do it one way or the other. When that happens, it can be helpful to fall back on thrust to maintain depth until buoyancy control clicks.

I believe horizontal ascents/descents have clear advantages over vertical, but being horizontal can complicate the process of mastering buoyancy for new divers by adding components that don't exist in vertical attitude. Bladder tacoing is one example where a new, unsupervised diver might struggle in getting the wing to vent completely. Properly weighted and near the end of the dive, I've seen experienced divers cork when they get shallow for exactly that reason.

Situational awareness is lacking in most new divers. As a result, ascents and descents are one of the most likely phases of the dive to lose a buddy in limited vis. A new diver in vertical trim can rotate 360º with relative ease and speed, enabling to scan a much broader area in a shorter time, than if they were horizontal.

Now, if you have access to a solid mentor or instructor, that's a different story.

 

[Diver0001]

I know the general answer is to do it slowly, but what techniques are used for safe descent and ascent. I found myself falling like a stone in 30 feet of water and realized I didn't know what I was doing. It scared the hell out of me, and fortunately no permanent damage to my ears. While I'm taking a few weeks off to allow my ears to recover, I thought I'd research the best techniques. Please help.

I need to get to bed becuase I'm diving in the morning and I haven't read the other responses but since everyone is going to tell you to descend horizontally, I'll give you a different perspective, which is how I teach people to *initiate* the descent so it's under control.

What works is this: Once you start deflating your BCD do these things in this order:

• hold a neutral volume of air in your lungs as you start to sink. You can breathe in and out as long as you're not holding your lungs full or empty most of the time.
• deflate until your head is *just* under the water and then STOP deflating.
• look down at your feet and bend the knees if necessary to cause you to tilt forward instead of back. This also has the advantage of reminding you to look where you're going!
• breathe out until your lungs are empty. You'll start to descend but it won't be "like a rock"
• at this point you can use the air in your lungs to control the descent through the first few metres. If you want to descend faster then hold your lungs mostly empty by breathing in with short breaths and then exhaling right away again. If you want to slow down then breathe in more deeply.
• adjust your BCD with short burts as the speed to descent starts to increase.
• repeat the previous two steps as needed for the desired rate of descent.

This advantage to this form of descent is that you can stop the descent by breathing in, especially in the first few metres where problems are likely to show up. That's handy.

It's also completely under diver control and puts you in a good position to maintin buddy contact during descent

and once you look down at your feet you'll start to go into a swimming posture naturally without any work.

Ok. that's it. Just one more thing. If you're falling like a rock, you might want to do a buoyancy check. Good chance you're using too much weight.

R..

 

[Jim Lapenta]

In my classes we begin by first of all properly weighting the diver. At the beginning of day one on scuba. This will change over the course as students get more relaxed and confident. The first descent is done horizontally by just laying forward in the water and dumping air from the bc if any is in there. Since we have already done a proper weight check there is no reason for the diver to sink like a stone. We then just lay on the bottom and breath for a few minutes. I will then have them use the inflator in very small bursts while keeping their breathing steady. We'll then move out over the first step in the pool between the 4ft section and the 7ft. I'll have them get their torso out and practice getting neutral. We'll do mask clear and r&r, reg recovery, and weightbelt inthe horizontal position.

Then it's time for a little swim out over the 10 ft section. At this point I'll indicate to them to get SLIGHTLY head down and exhale a bit more than usual. The result is they slowly float down to the bottom. I have them lay there for minute and then ascend at a virtual crawl pace up the pool contour while dumping short bursts of air. We do not do vertical ascents and descents until session three on scuba. I want them to see that it is much easier to control the rates of both if they are properly weighted and already in the flared position we have already discussed in class for controlling runaway ascents and descents. The second lecture between pool sessions one and two are where we introduce the concept of buoyancy to OW students in our system. This is also just before I put students on scuba. Last night I had a private session for a lady in one of my OW classes who was having some mask issues. She did fine in the remove and replace on snorkel. But on scuba she was having trouble not inhaling through the nose a bit of water. She also was putting herself under to much pressure to not hold up the other two students. I'll post about what we did in another thread to get her over this but during this time I was myself a bit taken aback by how gently and controlled her ascents and descents were. She was actually like a snowflake on both. Controlled, she did her own weight check since she had a different suit on, just a little on the inflator.

In fact most of the time she didn't have her hand on it. I actually asked her if she had somehow been practicing. She said no that all she was doing was what she saw me do and I did tell them how I did it. So wasn't that what she was supposed to do? Yes snowflake, that is exactly what you are supposed to do.

 

[satwar]

Thanks for the great feedback

This weighting business has me rather confused. I thought proper weighting was to enable the execution of a safety stop @ 10-15 feet with an empty tank (700 psi) during final ascent.

 

[Jim Lapenta]

That is part of it. The other part is to allow you to maintain your depth will small adjustments to your bc. If you can hold a stop with say 12 lbs of lead on why would you need to use 16 or 20 or more. All that does is add to your drag and increase air consumption. IN fact overwieghting can actually CAUSE a runaway ascent. If you are using too much weight and you have to add excessive air to the bc to maintain buoyancy, should you begin to ascend and for some reason not be able to vent fast enough the air can expand too fast and catch you off guard. By the time you realize it you're on your way and if you do vent you are then headed back down like a rock. This should have been covered in your class. How many weight checks did you do and did you record the amount you used on each one. This is SOP in my classes.

 

[Quero]

Nuff said on weighting, I think.

Given your experience level, I'd recommend starting out doing your ascents and descents vertically. Being vertical facilitates the dumping of gas from your BC to counter positive buoyancy and finning to counter negative buoyancy. For new divers, this can be much easier initially, than attempting a horizontal ascent before they have a solid handle on buoyancy control.

Ideally, you want to be able to arrest ascent or descent with your breath. If that's not possible, you need to add or dump gas from your BC. It takes some time to get the feel for how much to add or dump, so it's common for new divers to over do it one way or the other. When that happens, it can be helpful to fall back on thrust to maintain depth until buoyancy control clicks.

I believe horizontal ascents/descents have clear advantages over vertical, but being horizontal can complicate the process of mastering buoyancy for new divers by adding components that don't exist in vertical attitude. Bladder tacoing is one example where a new, unsupervised diver might struggle in getting the wing to vent completely. Properly weighted and near the end of the dive, I've seen experienced divers cork when they get shallow for exactly that reason.

Situational awareness is lacking in most new divers. As a result, ascents and descents are one of the most likely phases of the dive to lose a buddy in limited vis. A new diver in vertical trim can rotate 360º with relative ease and speed, enabling to scan a much broader area in a shorter time, than if they were horizontal.

Now, if you have access to a solid mentor or instructor, that's a different story.

Dave, what you say makes a great deal of sense for some, maybe many, situations, but where I work, I want even novice divers horizontal as soon as I can show them how. We have a lot of coral here, and I find that novice divers tend to break it on feet-first descents precisely because their situational awareness is still developing. They don't realize just how long their bodies are with fins added to the length, and they don't remember to look down enough to see if there's a big fan below them. On the other hand, we have great viz, mostly, so losing a buddy due to limited viz is unlikely (I imagine that this happens more in places where the water is murky, which are also places mainly devoid of coral). The upshot is that I teach divers to descend horizontally as soon as possible. Getting their weighting right for that is critical. This is just one more example of how our teaching has to mesh with the specific demands of the dive environment.

 

[Quero]

She was actually like a snowflake

This is a great image. I'll add this to my repertoire of "mental imagery" for my students--at least those who know from personal experience what a snowflake is like when it falls gently. Thanks!

 

[Quero]

Thanks for the great feedback

This weighting business has me rather confused. I thought proper weighting was to enable the execution of a safety stop @ 10-15 feet with an empty tank (700 psi) during final ascent.

That's certainly one aspect of proper weighting, but the need for extra weight (beyond what you need to get off the surface with a full tank) to counteract a nearly empty tank shouldn't amount to so much that you will plummet to the bottom "like a rock." The additional amount of weight you need to stay at 5 meters/15 feet is only about 4 pounds. Even a couple more pounds beyond that will make your initial descent quite a lot faster.

 

[stakanak]

One problem with the issue of "falling like a stone," whether or not you are over-weighted.
Since you have your inflator in your hand add air to slow your descent!
This seems like a panic situation and one that should be sorted out before you dive again, preferably with an instructor.
Please understand that I am not trying to be a jerk-as a new diver I know the learning curve is intense in the beginning, but these are occurrences that should not happen.
You were very lucky you were in 30 feet of water and not 100. Slow is pro...
Good Diving