Equalization: Deep vs. Shallow

[sambolino44]

I just read a discussion of an apparent reverse squeeze on the ascent from a deep dive. No mention of how deep this particular dive was, but for this discussion, let's use the term "deep dive" to mean deeper than 80 and less than 130 fsw.

I've seen several discussions of equalization that refer to how deep the dive was.

Now, the way I understand equalization it would seem that to a certain extent any discussion of how deep the dive was is irrelevant. My reason for this is that our bodies can only withstand a very small difference in pressure before we suffer pain and damage. So we must equalize after only a small difference in depth, like 5 or at the most 10 feet. OK, maybe we can get all the way to 20 feet without permanent damage, but I can't get anywhere near that deep without having to equalize.

The point is, once you've equalized to the ambient pressure at whatever depth, the whole deal starts all over again.

Now, if someone had a catastrophic injury at 130 ft, say they bumped their head and caused swelling that completely closed their eustachian tubes, I guess you could say that would be worse than the same injury happening at 10 ft. You might be able to get back to the surface in that condition from 10 ft, but no way from 130 ft without some kind of major blow-out. But this example is not typical of the kind of discussion I've seen concerning equalizing and deep dives.

I guess the point I'm trying to make is that some people don't seem to understand that, as long as your ability to clear doesn't change over the course of the dive, there's not much difference between a deep dive and a shallow dive, as far as equalization goes. And that's because we can't get very far from whatever depth we equalized at before we have to equalize again.

This all seemed to make perfect sense before I put it in writing, now I'm wondering if I'm getting my point across. I'd like to hear what others have to say about this subject.

[TSandM]

The difference is that, on a 30 foot dive, you might equalize your ears three or four times. On a 120 foot dive, you might have to do it a dozen times. If you're a little late on equalizing once, it's no big deal. But if you are late a dozen times, by the end of the dive, you'll have significant edema of the structures of the middle ear.

[sambolino44]

So, I guess I was thinking about it in terms of how far off from "equalized" you get, but you are pointing out that how many times you get away from being equalized is also a factor.

[Walter]

Originally Posted by sambolino44

So we must equalize after only a small difference in depth, like 5 or at the most 10 feet. OK, maybe we can get all the way to 20 feet without permanent damage, but I can't get anywhere near that deep without having to equalize.

It's not the distance, it's not even the amount of pressure change, it's the % of pressure change. For example, the pressure change for a 5 ft change of depth (fsw) will always be 2.23 PSI. That is significant when moving from the surface to 5 ft or from 14.7 to 16.93 PSI. That's a change of 13%, but when moving from 95 to 100 ft, while it's still a change of 2.23 PSI, it's a change from 57.02 PSI to 59.25 PSI or a change of 3%, not likely you'll even notice.

You can't dive to 20 ft without equalizing because there's a pressure change of 38%, however a change from 100 to 120 ft is similar to the change from the surface to 5 ft, approximately 13%.

Originally Posted by sambolino44

The point is, once you've equalized to the ambient pressure at whatever depth, the whole deal starts all over again.

Only if you stop at that depth for awhile then continue your descent. If you continue to descend, your equalization process should be continuous, not stop and start.

Originally Posted by sambolino44

I guess the point I'm trying to make is that some people don't seem to understand that, as long as your ability to clear doesn't change over the course of the dive, there's not much difference between a deep dive and a shallow dive, as far as equalization goes.

We don't understand that point because it's simply not true. The deeper we are, the easier it becomes to equalize. The % change for every foot we descend descreases the deeper we go, so the change becomes more gradual as we get deeper.

Originally Posted by TSandM

The difference is that, on a 30 foot dive, you might equalize your ears three or four times. On a 120 foot dive, you might have to do it a dozen times. If you're a little late on equalizing once, it's no big deal. But if you are late a dozen times, by the end of the dive, you'll have significant edema of the structures of the middle ear.

Exactly why the process should be continuous and not stop and go. When I equalize continuously on my descent, my ears are golden, when I screw up and stop and go, I severly limit my number of descents and my rate of descent.

[DA Aquamaster]

If you can't clear and feel pain it is obvious and divers address the issue.

What is more insidious is when you a diver can only partially clear and then feels no pain but just some mild pressure in the ears or a slight but not yet painful squeeze in the sinuses. Over the lenght of time you are on the bottom substantial swelling can occur and a reverse block is a real possibility. I think the failure to equalize for small changes over long periods of time on the bottom causes more issues with reverse blocks than failing to clear during large changes on descent.

Equalize early, (starting on the surface) equalize often (every few feet when shallow) and equalize on the bottom even if you don't think you need too.

[sambolino44]

Walter, I agree with everything you said, but you are actually reinforcing the point I was struggling to make. It seems to me that when most people discuss equalizing on deep dives, they feel that the deeper you go, the more... I don't know how to express it.

I just brought the subject up because it seemed to me that there are a lot of people who feel exactly the opposite as Walter.

Now to your point of continuous equalization, I've tried (a few times) other methods of equalization, but the only way that consistently works for me is the Valsalva. I have to inhale, so that can't be completely continuous. I'd really like to be able to equalize without having to use my hands, but I just haven't spent enough time working on it.

You just brought up another subject I'm curious about: how fast to descend.

I do try to equalize early and often, and even when it seems unnecessary. But that's not the point of this thread. I was trying to see what other people think about equalizing on deep vs. shallow dives.

Thanks, everyone, for your responses.

[HawaiiFinnFish]

Aloha!

I work with a SCUBA company but I go freediving by myself while the tourists are in the water with their SCUBA equipment. I didn't equalize properly the second time at around 55 feet (yes, I know I should have equalized more often but I was way too fast). My ears hurt a lot now and I'm having trouble equalizing at around 25-30 feet. In order to let things heal, should I stop freediving and just snorkel on the surface for a while or is there something I can do to accelerate the healing process. I haven't talked to an otolaryngologist but a fellow diver recommended I stay away from freediving 1-2 months.

Aloha & Mahalo,
Marcus