Hey Hoover ~ Did you ruin someone's dive?

[lamont]

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.

I've got 70 dives now. I started doing "math-based SAC" back around dive #25. It immediately made me way more comfortable on deeper dives, so i stopped checking my gauges every 3 mins. I try to make it part of my dive plan to figure out what my SAC (in psi/min) will be at depth, at what time I expect to hit my turn pressure or how many psi I expect to have left at the NDL, and if I'm diving with new people or new profiles, and particularly if I expect they may hit rock bottom before I do, I try to come up with the same number for them. It makes for dramatically less guesswork and less stress at depth.

 

[STOGEY]

When I am diving with someone, before we begin the dive. I usually tell the persons assigned to be my buddy. That if we run low on air, that we can inform the other person that I am low on air and that if the other person wants to accompanay the other person they can. But if they don't want to, well we'll see each other when we get to the top or the boat. No big deal.

Now some dive ops/boats say that when the first one hits the reserve mark lets say 1000psi, evreyone is supposed to begin their ascent. If you think that I'm going to jeopardize my safety just to extend your dive,You'er the one with the problem.

Some dms/instructors do give people the option of staying on the dive while the others start their ascent.

So Uncle Pug lighten up.

 

[MXGratefulDiver]

So Uncle Pug lighten up.

LOL ... if he gets any lighter we'll have to call him Mr. Helium ...

... Bob (Grateful Diver)

 

[Dive-aholic]

OK, a few comments. UP described some Hooverish behavior, but didn't give any empirical evidence of exactly how high a SAC or RMV needs to be to be a fully qualified Hoover.

So, here's my proposal for a strict definition.

A Hoover will suck a AL80 to less than 1000PSI in under 15 minutes at 66fsw.

Mathematically, that means they used 2/3rds of 77cf or about 51.3cf which equates to SAC rate of 1.14 if my figures are right.

What do you guys think?

Would that be in calm water or a strong current or somewhere in between? Also, is it tropical 85 degree water in a 2/3 wetsuit or 40 degree water wearing a drysuit with 400g undies or somewhere in between? Also...

 

[grazie42]

My tmx instructor told me that 15 ltrs/min was a pretty normal AC...what that means in cft/min would give me a headache to try to figure out...maybe someone bi-lingual can help out? anyways to me that means that a SAC of about 20 ltrs/min would be "hooverish"...around 1cft/min? maybe? That would be pretty close to what android came up with...

 

[Lawman]

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.

Yeah, since I got these twin 250s I get at least 30 minutes @ 50'.

 

[TCDiver1]

About 0.035 CF per Liter so at 15 liters per min you would be at about 0.53 CF per minute. A pretty good SAC IMO.

Ps:
You gotta watch out for Lawman and his twin 250's. Its quite a site to see.

 

[Uncle Pug]

This didn't happend to me... but it has happened to others.

This is for those of you (noble souls) who would never turn down a hoover as a buddy and are more than willing to sacrifice your dive.. because after all... you were a tadpole at one time yourself...ect...

Here is your scenario ~ answer honestly:

You aren't rich but through hard work and saving you've finally realized your dream and are on a dive trip to Fiji. You have no buddy along (the reason dosen't matter.) The day comes when you finally get to dive in the fabled Beqa Lagoon. The boat is a mix of buddy pairs and singles with several Fijian DMs diving as well.

1) Do you offer to dive with the newly certified and obviously nervous fidgety guy who already has his reg in his mouth while sitting there on the boat? Remember... you are a noble soul... you were once a tadpole.

As it happens nobility doesn't come into play... the DM *assigns* you to the fidget. It is as you surmised... he is not only a tadpole but a shop vac. He sucks his air down in what must be record time. You've barely gotten to the bomies and the soft corals beckon... but your *buddy* is showing the DM his gauge and you know what that means.

2) Do you inwardly wish that the DM would just take *your buddy* and allow you to continue your dive since you still have 2/3 of your air left?

3) How do you feel when the DM gives you the <pairupwithyourbuddyandascend> signal?

4) How do you feel back on the boat as you sit out what would have been 45 minutes of your dive while the *shop vac* exults to the skipper how great the dive was completely ignoring you?

Hmmm?

 

[OE2X]

I would pick number 2 and 4. Then on the next dive I would find another buddy.

 

[Uncle Pug]

Those aren't choices to pick... those are questions to answer... how do you feel? Answer all of them.