Snorkels for freediving

[rcohn]

Missing reference from previous post, Kinsler and Frey, Fundamentals of Acoustics, J. Wiley and Sons 1962 page 77.

The change in stiffness due to snorkel curvature really should not matter in diving, but here is information the changes in bending with a curved beam anyway, from Roark and Young, Formulas for Stress and Strain, 5th ed., McGraw Hill, 1975. Chapter 8 "Curved Beams" page 209.

When a curved beam is bent in the plane of initial curvature, plane sections remain plane, but because of the different lengths of fibers on the inner and outer sides of the beam, the distribution of stress and strain is not linear; the neutral axis therefore does not pass through the centroid of the section and Eqs. 1 and 2 of Art. 7.1 do not apply. The error involved in their use is slight as long as the radius of curvature is more than about ten times the depth of the beam, but it becomes large for sharp curvatures.

Ralph

 

[Toeter]

I think that in the small/big bore discussion the problem of rebreathing your air is not that important, I think.

The air I rebreath is only a small portion of air I take in.
When I am snorkeling I vent about 3 to 4 liters of air each time.
I have 3 snorkels 'in the house' and they have a air content of 150 to 175 ml (all big bore).
So each time a take a breath I am rebreathing 175 ml of air (max).
In this air there is still 16% O2, so enough for me to breath, I only need 4%.
I think the content of a small bore will be around a 100 ml(?), so the difference is not that big.

Does this make sence or am I barking up the wrong tree here ?


My main concern is the resistance I feel when I'm breathing.
I tried a couple last week and for me was the shotgun the winner, so I choose that one.

Respect !

 

[Toeter]

Today I realized I was barking up the wrong tree.

The supplie of O2 isn't the problem, but the level of CO2......:banging:

On every exhale you produce 4% CO2, that's not good to keep on rebreathing this.

But I understand that if your snorkel has a air content around the 150 ml that this causes no problems.