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Freediving Mask Volume Tests

by Giovanni Cirillo

Finally after manufacturing the final version of the Mask Volume Reducer I did some measuring to verify the volumetric performance improvement that such tool provides as well as measuring the volume of my masks.

What is the actual internal volume of a given mask is somehow debatable. An absolute value cannot be given as the actual mask volume greatly depends on the conformation of the wearer face. For marketing reasons masks are designed to fit all type of faces thus the lowest volume will be achieved by somebody with a big nose, bulging eyes and round and flabby face. This being will be able to "fill" the mask with his ugly face thus reducing the air space in the mask to a minimum.

Given that to equalize 100 ml of mask air volume (about 2/3 of an average mask volume) at a depth of 60 m requires 500 ml (0.5 liters) of surface lung volume or about 10% of the average human being total lung capacity, it can be said that the physical attributes of the ultimate freediver start with the face conformation and appearance. The uglier the better!

The removable Mask Volume Reducer I manufactured has a volume of 95 ml which reduces my Falco down to 60 ml without reducing the field of vision. A 62% volumetric performance improvement.

Going back to the mask measurements here are the values as applicable to my face (very skinny, deep eye sockets, big nose).

Technisub Sphera140 ml
Technisub Falco155 ml
Seac Extreme155 ml

The measurement tests were done in the following "rustic" yet precise manner. I invite anybody that has a scale that has an accuracy of 5 grams or less to measure their mask and let me know the results. In alternative a quality measuring cup with a span of about 0-250 ml or cubic centimeters can be used. The idea is to fill the mask with water and measure the quantity either in either grams (1gr of fresh water equals 1ml=1cc) or directly in volume with a measuring cup. Fill the kitchen sink with warm water, drop the mask to the bottom, flip it underwater to remove entrapped air under the seal lip, dip your head in the water and put the mask on while holding the head underwater. Raise your head, let the excess water drip and then swing your head over a light weight plastic container located on the scale. Carefully remove the mask over the container making sure not to spill any of the content outside the container.

The amount of water collected will be your volume, repeat the test a few times and average out the results. The result can be somehow lowered by say 5 ml to account for some water that enters the nostrils and should not count as mask volume as such. For the ones that seek precision, I suggest doing the test in the bath tub submerging the head while keeping it upright so that water cannot enter the nostrils.

Considering the recent competition rules changes regarding the freedom of using any type of mask or apparatus, we should see noticeable depth improvements in the future. Especially for those that go deeper than 40m, 150 ml of mask it's a lot to equalize!

Dive safe


Reader's Comments:

Please leave your comments or suggestions below!
 What material was used for this purpose? I was thinking that silicone caulking could work... just mould it in a plastic bag or something similar.

What was used for your "volume reducer"?

Much thanks,
 hi giovanni this is arjun from india,bangalore i've been swimming for 5 years now im interested to learn freediving,please guide me.
 Hi, your measuring will get more precise if you just put all the water into one bowl, and do the measuring after everything is inside. I have exactly 900ml after 5 measurements, so I have 900/5 = 180ml volume.
 Great suggestion, Martin
 I am interested in a mask volume reducer from Giovanni Cirillo for my Falco mask. How can I contact him?

 I think a while back he was selling all of his mask-reducing materials. Check your email.


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