Free SSI Science of Diving Specialty

[BlueTrin]

Well sure. I'm not saying that they may have been faulty, just that they may have been overly simplified in early implementations.

I guess someone could check how the data points were obtained for the current models and see if they tried to model the effect of whipsaw profiles ?

 

[dmaziuk]

I'm sure it does for off-gassing, but it's questionable of what they do in sawtooth profiles. The tables use Haldane's models too, but that doesn't make them suitable for sawtoothing.

No.

The way it works, on/off-gassing rate of a "tissue compartment" is based on time. Whether it's "on" or "off" is based on delta-pressure "inside" and "outside" the tissue.

"Fast" compartments will off-gas when you go shallow and on-gas when you go back down. "Slow" compartments will not have time to off-gas (significantly) during the shallow phase and overall will (may) keep on-gassing.

The overall picture depends on the number and half-times of the compartments: Haldane had 5, Buhlmann has 16, etc., and like an integral, adding infinitely more infinitely thinner "compartments" will get you infinitely closer to the exact answer.

But you don't need the exact answer. You only need to get out of the water not bent. The models are good enough for that, have been since Haldane.

 

[BlueTrin]

I asked SSI by Facebook messenger what is the source of this statement.

Will update if I get an answer

 

[saxman242]

No.

The way it works, on/off-gassing rate of a "tissue compartment" is based on time. Whether it's "on" or "off" is based on delta-pressure "inside" and "outside" the tissue.

"Fast" compartments will off-gas when you go shallow and on-gas when you go back down. "Slow" compartments will not have time to off-gas (significantly) during the shallow phase and overall will (may) keep on-gassing.

The overall picture depends on the number and half-times of the compartments: Haldane had 5, Buhlmann has 16, etc., and like an integral, adding infinitely more infinitely thinner "compartments" will get you infinitely closer to the exact answer.

But you don't need the exact answer. You only need to get out of the water not bent. The models are good enough for that, have been since Haldane.

I'm not disagreeing with you there. My question is more along the lines of how, particularly in early computers, that was implemented. I suspect the reality is we won't ever know exactly what was done.

 

[dmaziuk]

I'm not disagreeing with you there. My question is more along the lines of how, particularly in early computers, that was implemented. I suspect the reality is we won't ever know exactly what was done.

It doesn't matter: early or not, the base model assumes symmetrical off- and on-gassing. If you're on a perfectly symmetrical sawtooth profile, your calculated loading is the same as a straight-line at average depth.

It's the later models, specifically bubble models, that care about those things.

 

[dmaziuk]

I guess someone could check how the data points were obtained for the current models and see if they tried to model the effect of whipsaw profiles ?

Be careful with what you ask for.

https://www.history.com/news/staged-decompression-bends-diving-goats

 

[Steve_C]

These are not complicated dynamical systems. Any good computer can run them in close to real time no matter what your dive profile is. The parameters may have taken a while to get from statistical studies and experiments but once they are decided on it is straightforward to run the model.

 

[Ben_3]

For the free class do I have to sign up through an SSI shop or can I just sign up online?

 

[Sloeber]

For the free class do I have to sign up through an SSI shop or can I just sign up online?

Click this link - https://cozumelscuba.com/sod/

Complete the form and I'll get you registered for the class and send you instructions.

 

[Sloeber]

My class has been unlocked and I'm registered now with SSI. Can't find where to click on "My Training" in the tool bar. Maybe it's not there yet because it's not April 12 yet?
Also, are the SSI tables provided in the course (I have none)?

Click Programs & Cards > Programs > Science of Diving on a desktop machine.

Or on mobile click Programs & Cards > Courses > Science and Diving

Tables are located at Programs & Cards > Tables on your mobile device.