Let's say that you were doing a dive in Madison Blue (no scooters). Would you double stage it, and go to 1/3's on backgas, or would you only stage the 80's and not touch the backgas?
Assuming that you are staging 80's, and diving 1/2+200, you would use approx 70cf of gas. Now a set of 120's run at thirds would give you 80cf of gas, without the drag of the stages.
I guess my question is, on a double stage dive if you're not going to touch your backgas, would it not be more efficient to dive the doubles to 1/3's instead of staging?
Thanks
You get these nonsensical results in theory only. This is partially in answer to the question below too.
First, a double stage in Madison isn't a very good idea. That puts you with two stages going through crossover or one through rocky horror. So, I would single to Rocky Horror, dive the stage to halves and then use about 1/4 of total gas if it was a squared away team that could quickly exit that cave in a gas share.
You need extra gas on scooters and stages usually = scooters. So, two stages and full back tanks that don't get touched on a scooter dive which allows you to cover much greater distance and allows your SAC rate to stay much lower than swimming makes perfect sense to me.
There is nothing wrong with having too much gas. Now, a simple swim dive where the objective can be reached on back tanks to thirds. Probably wouldn't bother with stages in the first place because you cover much more distance without them swimming.