Hey Hoover ~ Did you ruin someone's dive?

[wedivebc]

Gas managment is something totally different from calculating SAC-rates. Gas managment is dive planning. And yes, that's very important.

Calculating SAC rates for different workloads is... guesstimating based on... are you ready?... ready??... EXPERIENCE!

You can apply any which formula you want, you'll still need past dive data to work with.

So, a new diver will have to guess, based on the few dives he or she has already done. Don't expect a very accurate estimate though. Which is why a new diver should restrict himself to dives well within the NDL and with the option of a direct ascent until said diver has enough data to work with.

My experience has been that most folks breath pretty consistantly from dive to dive based on a given workload. You can gather the baseline data within 1 dive if you take good readings and apply them to your diving. What you are calling balderdash is actually very useful data and you may want to try it before you knock it.

 

[kalvyn]

We just did some dives this weekend with a newbie, on a 4 person team. It was part of the plan - newbie drains can, we escort newbie to the boat, watch their safe ascent to the step, and the three of us continue diving for another 25 - 30 minutes. Worked fine.

This is exactly what we did this week in Provo... my father-in-law isn't just a hoover, he's a HOOVER. We dove as a foursome (me, his wife, my wife and him) and we just dumped him off at the anchor line, continuing our dives. I tried to work with him this week to get his SAC down, but he's not too big on the listening thing, I'm afraid. He did improve, though... he got a couple 40 minute dives by the end of the trip.

Lastly, I'll echo what a lot of folks have said already: I was that hoover not too long ago (and I still am in relation to Uncle Pug!), so it's my duty to give back what was so freely given to me when I sucked (literally).

Jimmie

 

[FatCat]

My experience has been that most folks breath pretty consistantly from dive to dive based on a given workload. You can gather the baseline data within 1 dive if you take good readings and apply them to your diving. What you are calling balderdash is actually very useful data and you may want to try it before you knock it.

Between my fourth and my twenty-fifth dive, my gas consumption went from 150 bar for a 35 min dive to -15 metres to 120 bar for a 50 minute dive to -30 metres. Now, years later, I can do the same 50 minute dive on 80 bar.

I have found that most beginning divers go through a comparable process.

Math based SAC: I've tried it, I found it lacking for newbies and I give newbies helpful tips for future reference.

Everyone: please stop trying to apply abstracts meant for the more experienced to specific circumstances for new divers.

 

[wedivebc]

Between my fourth and my twenty-fifth dive, my gas consumption went from 150 bar for a 35 min dive to -15 metres to 120 bar for a 50 minute dive to -30 metres. Now, years later, I can do the same 50 minute dive on 80 bar.

I have found that most beginning divers go through a comparable process.

Math based SAC: I've tried it, I found it lacking for newbies and I give newbies helpful tips for future reference.

Everyone: please stop trying to apply abstracts meant for the more experienced to specific circumstances for new divers.

Who said this thread was directed at newbies? Do you think the guy who started it is a newbie?
I teach open water students about sac rate and I don't see what's abstract about it.

 

[OE2X]

Pug doesn't do that - he'll stay wet from a leaky drysuit, cold and miserable for an entire 60 minute dive so he doesn't cut his buddy's dive short. He lays it on pretty thick after the dive, though - even to the point of embellishing with uncontrollable shivering, blue lips and wet undergarments

Not only will he do that on the first dive, but then, he will still do a second dive all wet and cold. Pretty good buddy!

 

[FatCat]

Who said this thread was directed at newbies? Do you think the guy who started it is a newbie?

Most airhogs are newbies.

I teach open water students about sac rate and I don't see what's abstract about it.

I teach open water students that their air consumption will vary according to the environment they will dive in. I show them the basic math and then I show them how I do it.

Mostly, after a year or so, I ask them about math based SAC. Usually we have a good laugh about it, and then we move on to serious gas planning, based on real experience and adapted to the dive.

 

[Lead_carrier]

If I was the hoover then I'd feel no more obligated to pay for my buddy's dive than I would expect them to pay for mine if they had an equipment malfunction and need to do an unplanned air shared ascent.

 

[diverbrian]

SAC means nothing. My air consumption at depth has no fixed relation to my SAC. SAC calculations are always off by at least 30 bar.

I do have a very good idea of how much air I will consume given a certain dive profile. This however, is something you can only learn through experience and by monitoring the history of your air consumption.

By the way, SAC is not the useful number number as it measures pressure from the tank/min relative to surface use of gas.

What we want to look at is RMV which is the volume of gas breathed relative to the surface use.

To illustratate the point, a SAC rate would 40 PSI/min. An RMV would be .5 cu. ft./min. The RMV can be used to adapt to larger/smaller tanks a little more easily.

And a thumb is a thumb. My buddy or I could get cold easily (I know I have those extra thick drysuit undies for a reason.) which may lead to me calling a dive with plenty of gas left. My dive buddy may have equipment malfunctions or not be able able to clear ears. All of these, by current standards put me back on the boat. I seldom solo dive off of a boat and when I do, it was discussed topside before we submerged. Besides, my normal recreational buddy hates to hear about me diving solo. She was trying to make me promise to give it up and not just for Lent.

 

[Lawman]

And I'll be glad to pay you for the portion of the dive you missed.
You can use the money to have my foot removed from your butt.

 

[diverbrian]

And I'll be glad to pay you for the portion of the dive you missed.
You can use the money to have my foot removed from your butt.

Actually, you had my old recreational dive buddy on the last Toby trip where I met you. He said that you did great on the last day that you were there.