SAC rates for "Everyday Joe's"

[flymolo]

BTW the reason I am gathering this info is to get a rough idea of how much bailout different divers might need on a project with a standardised dived profile that will be repeated day after day.

What SAC rate were you taught to use for your bailout calculations during your CCR training?

 

[Nick_Radov]

BTW the reason I am gathering this info is to get a rough idea of how much bailout different divers might need on a project with a standardised dived profile that will be repeated day after day.

Every diver needs to calculate their own gas plan for every dive. A project manager can double check that they have performed those calculations, but you shouldn't be doing it for them.

 

[RedSeaDiver2]

How do you want to measure the reserve, in cuft/liters or psi/bar?

Is everyone diving the exact same tanks?

This will hopefully tell me whether everyone will be able to run with the same size bailout tanks which will make our lives easier...

 

[RedSeaDiver2]

Every diver needs to calculate their own gas plan for every dive. A project manager can double check that they have performed those calculations, but you shouldn't be doing it for them.

Totally agree - this is just to give me an idea of what things are more likely and less likely - there is a loooong way to go before anyone gets in the water on this project

 

[lowviz]

So everyone will dive the same depth and runtime?

What is the rough depth and estimated runtime?

 

[inquis]

RMV is respiratory minute volume.

Dang autocorrect! Thanks.

 

[boulderjohn]

SAC rate stands for Surface Air Consumption - that rate is calculated before factoring in currents, caves and depths

Different people use the SAC and RMV differently. There is no universal definition.

 

[boulderjohn]

What people will tell you on a forum and what you see in real life is completely different.

Dive computers being what they are today, pretty much every student I have had start a tech class in the last few years comes to the class ready to tell me their SAC rate. Pretty much all of them claim better rates than I have. Now, I am not a superman for SAC, but I am surprised when new students claim to be better. Then we do the class. I have indeed had experienced diver students with better rates than mine, but most in reality turn out to be far heavier breathers than they claimed to be. I don't think they were lying, so I can't explain it.

 

[inquis]

I have indeed had experienced diver students with better rates than mine, but most in reality turn out to be far heavier breathers than they claimed to be.

I noticed my SAC increased substantially at the beginning of tech classes but then returned to normal by the end of the class. I chalk it up to finally being comfortable with the skills & material.

 

[sea_ledford]

BTW the reason I am gathering this info is to get a rough idea of how much bailout different divers might need on a project with a standardised dived profile that will be repeated day after day.

When I am doing large scale planning, like you are currently, I use 0.7 cuft/min. That is a little high for the average diver that will be conducting the types of dive you'll be doing, but it also makes it a little more conservative. Chances are if a diver is bailing out, they aren't going to be at their normal 0.5 or below RMV, so 0.7 takes that into consideration.

What it DOESN'T take into consideration is any sort of significant CO2 hit. If your study area is small enough, you might consider staging a good chunk of emergency gas on the bottom, on the line, and at a deco station. You can't carry enough for a big hit, it would have to be staged.

Also, depending on how much physical work you will be doing at depth, you might want to get hold of some people that do actual work at the depths you are talking about on CCR for advise. There aren't very many of them. Diving to 65M and swinging a hammer at 65M are not the same thing.