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mouthfill technique?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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New Member
Sep 12, 2003
Can someone explain the mouthfill technique? When I first read about it, it sounds self explanitory enough. Just fill your mouth with air around 35-40 meters. However, I tried it yesterday, and at 35 meters, tried to fill my mouth with air, but my cheeks were still sucked in from negative pressure. I had to frenzel the rest of the way to 40 meters, and that was it, I was done, couldn't reverse pack any more air.

In Eric's recent post, it almost sounds like the diver stops the descent, turns horizontal, and then fills the mouth. Is this the way it is done?

Thanks in advance for any explanation.

The mouthfill technique is so hard to learn that only a few people in the world can do it effectively. If you were to 'succeed' on your first few tries, you could be pretty sure you weren't doing it properly.

Eric Fattah
BC, Canada

You're missing the point. Filling the mouth itself is very easy, you can stop if you want, and turn horizontal if you want.

The hard part is equalizing your ears with the air in your mouth, without allowing the air to escape back into your lungs.

Further, getting a nice, BIG mouthfill requires a complicated body position. A small mouthfill will still get you deep, but not nearly as deep as a big fill.

The secret in general is to decouple the epiglottis and soft palate. You must be able to keep the epiglottis closed, and relax the soft palate, whereas the reflex is to close the epiglottis and raise the soft palate, which makes equalizing impossible. Thus, the average person fills the mouth, finds the air STUCK in every sense of the word (won't go anywhere), then, in trying to DE-STICK the situation, the air escapes back into the lungs.

Eric Fattah
BC, Canada
Thanks for the explanation Eric. I also found an old post, where you drew a nifty picture of the body position most conducive to get a big mouthfill. I am going to give it a try tommorrow.

Thanks again,
Heh, I was wondering about that. I simply could not get it to work, the air allways sneaks back in to the lungs. Glad to hear that is supposed to be hard! That just means that I need to practise more. It sounds so simple...Just fill your mouth and frentzel.

No worries though, I'm still quite far from actually needing it. But it would be nice to know it when the need arises.
I can attest that Eric is right - it took me the best part of a year to be able to do it effectively. I don't get a massive fill, but don't need it really with the kind of diving that I do.

As with all 'techniques': once you have got it right a few times, it's much easier after that.

why don't you establish the depth where you do get a mouthfull of air? if 35m is too deep maybe it's working all right at 25m. it should be allowing you to get to 50m even with a not complete fill.

If you were to 'succeed' on your first few tries, you could be pretty sure you weren't doing it properly.

Probably, but just to add some hope out there, I was doing this technique automatically, prior to hearing about the technique, the first time I realized I was required to keep my epiglotis closed when reaching past residual volume. That is not to say I was doing it effectively. I was not using my tongue as a piston and therefore my cheeks were the only source of compression I was using. This did not allow a significant use of the air in the mouthfill and therefore stumped me as to what the problem was, when I could not equalize much further than normal.

For a year I did not figure out what was wrong with my technique, and then I finally read Eric's document and one of the techniques where you use the tongue to squeeze air out of a pinched nose, brought the sudden realization of what I was doing wrong with the tongue. I had taken the idea of using the tongue as a piston and was pushing the whole tongue up from the back and was not actually compressing the air. The air would move to the bottom side of my tongue. Next day I tried it the same as the technique described and life has been simple ever since.

My point is that maybe the technique requires some retraining of the body for some and for others it just requires attempting the whole combination of techniques, but if one is having trouble, I would first ensure that you have understood each step accurately and have the same picture as what is actually occuring in the body. It can actually be quite simple and easy. Maybe not for everybody, but there is hope. Avoid extended failure of this technique, by double checking the meaning and implications of the steps.


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Begin shallow


I have been practising the mouthfill since 2002 and it is really hard too learn. This season I can at least benefit from the technique EVERY dive and it has given me a capacity to equalize that is 15-20m deeper than with diafragmatic frenzel.

Three things made it simplier for me:

1. Practice at shallow water with FRC or on empty lungs, one mouthfill at the surface..

3. I make a sound ("uuuuuuuh"):D when I fill the mouth to get the right feeling, that forces me to really blow the air into the cheeks.

4. I start early to fill my mouth (~15-20m) then I equalize my mask, then I repeat the mouthfill and fill my mask and so on til I cant fill it any more ~30-35 (I'm not shure exactly). Then I close the epiglottis and the nose. This seems too give me a full mouth every dive, the bad thing is that it takes more power and concentration than filling it one time. From here I only equalize the ears (not the mask). The problem for me is that the mouthfill is often made too early or too late if I tried to do it one time when my D3 beeps.. (Thanks Alun for the tip!!!)
I fill my mask because I dont want to fill a squeezed mask with my mouth after the LAST mouthfill.
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Jim, that's an excellent thread!

I've been diving without packing lately, and now have to learn the mouthfill. I've found it very difficult as well! Now I'm practicing the passive exhale dives and filling my mouth at about 3m. So far I can only make it to around 10-11m, but sooner or later I'll get the hang of the mouthfill! It seems I should be able to fill my mouth at 5m or so and reach 15-25m... I've got aways to go yet! :)

Happy Practicing!
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