Why the choice of oral inflate SMBs?

[TSandM]

The instructors I spoke to require oral inflation for Fundamentals, and acknowledged that there might be occasions when other methods of inflation would be appropriate. Lift bags were a specific example.

Not speaking for the GUE instructional staff, I would think that, if I were shooting a large bag where the volume required would be significant, even at depth, I might want to fill it by purging because you can get a lot more air in very quickly than you can with oral inflation (at least if you have lungs the size of mine, where it might require several full breaths to get enough into the bag) and you can stop the filling and release the bag faster than you could if you were using an LP hose.

I've never shot a bag that size; I don't do much offshore diving and prefer to avoid really rough water when I do, so the small bags have always been sufficient for my purposes.

 

[LiteHedded]

The instructors I spoke to require oral inflation for Fundamentals, and acknowledged that there might be occasions when other methods of inflation would be appropriate. Lift bags were a specific example.

Not speaking for the GUE instructional staff, I would think that, if I were shooting a large bag where the volume required would be significant, even at depth, I might want to fill it by purging because you can get a lot more air in very quickly than you can with oral inflation (at least if you have lungs the size of mine, where it might require several full breaths to get enough into the bag) and you can stop the filling and release the bag faster than you could if you were using an LP hose.

I've never shot a bag that size; I don't do much offshore diving and prefer to avoid really rough water when I do, so the small bags have always been sufficient for my purposes.

that's along the lines of what I was thinking. sure certain bags (or when we fill a habitat) call for it but i dont think that's what they're addressing in classes. makes more sense

 

[Tortuga68]

If you're inflating high capacity lift bags for raising stuff, habitats or anything else that resembles a kiddie jumping castle, you're going to take dedicated bottle(s) to purge and not use your backgas. This has nothing to do with the OP.

---------- Post added April 4th, 2014 at 11:59 PM ----------

The reg removal is not the dangerous part, its getting the deployed reg tangled in the straps of the bag. Hence the reason (in part) for the non-locking LP hose inflators on the halcyon bags.

For beginners the small SMBs are fine, orally inflated typically works best since its one less hose thing in your hands (spool, and smb alone, no hose or reg needed)

The non-locking fitting is irrelevant if you are oral inflating. Also they now come with the option of a push-down screw fitting which I don't get at all.

Taking your primary out of your mouth in order to exhale your lungful of breath into an oral inflate SMB creates other potential issues, I am a little surprised at that given the emphasis during GUE FUndamentals on maintaining your air supply (e.g. during valve shutdown drills). I don't see any advantage compared to teaching reg-exhaled gas inflation to minimum required volume.

 

[LiteHedded]

If you're inflating high capacity lift bags for raising stuff, habitats or anything else that resembles a kiddie jumping castle, you're going to take dedicated bottle(s) to purge and not use your backgas. This has nothing to do with the OP.

---------- Post added April 4th, 2014 at 11:59 PM ----------



The non-locking fitting is irrelevant if you are oral inflating. Also they now come with the option of a push-down screw fitting which I don't get at all.

Taking your primary out of your mouth in order to exhale your lungful of breath into an oral inflate SMB creates other potential issues, I am a little surprised at that given the emphasis during GUE FUndamentals on maintaining your air supply (e.g. during valve shutdown drills). I don't see any advantage compared to teaching reg-exhaled gas inflation to minimum required volume.

reg removal and replace is one of the first things they teach in fundamentals. by the time the class is over i imagine you've taken the reg out of your mouth about a million times

 

[Tortuga68]

I'm so glad you're not prone to exageration

reg removal and replace is one of the first things they teach in fundamentals

No ****, it's also taught during OW. R&R doesn't require you to vent your lungs in between though.

 

[LiteHedded]

I'm so glad you're not prone to exageration



No ****, it's also taught during OW. R&R doesn't require you to vent your lungs in between though.

if you have an open ended or semi closed bag you can use reg exhaust to blow it if you dont want to remove the regulator from your mouth.
and your open water class does teach you to vent your lungs in between. what the problem is?

 

[Tortuga68]

if you have an open ended or semi closed bag you can use reg exhaust to blow it if you dont want to remove the regulator from your mouth. and your open water class does teach you to vent your lungs in between. what the problem is?

The problem is you don't appear to have read the thread. Nobody is talking about venting in the context you're referring to, aka OW 'blowing bubbles' - I'm talking about exhaling the total volume of your lungs to inflate an SMB; and I think it's already clearly established that we're talking about a closed circuit SMB since the title of the thread is "oral inflate SMBs". If you have a method to deploy an "oral inflate" SMB without taking your primary reg out of your mouth I'd love to hear it.

 

[TSandM]

Regulator remove and replace, and regulator exchange, are Fundamentals skills. If the student has a problem with taking the reg out of his mouth long enough to exhale into a bag, he needs work on being comfortable without a reg in his mouth. And what's the problem with exhaling? That's what you WANT somebody to do with their reg out of their mouth, right?

 

[LiteHedded]

I get what you're saying. i imagine during your fundamentals, Gideon had you use all kinds of smbs (depending on what was available). since you passed the class, I imagine you were able to complete this skill without too much trouble.
remaining stable while filling an oral inflate smb is a pretty trivial task. I'm sure you'd agree.

any issues I've raised in this thread are completely unrelated to these tasks. if a diver cannot comfortably complete these tasks (oral inflate SMB, reg exhaust into an open/semi-closed bag etc.) while maintaining their stability in the water, they need a lot of work before moving on to more challenging diving. in later classes you'll be expected to complete these tasks with a whole host of other things going on and it will need to be second-nature.

 

[MXGratefulDiver]

I think there's a mixing of terms here that have people talking across each other. "Oral inflate" means different things, depending on the type of bag you're talking about.

For the small bags, taking your reg out of your mouth and blowing air into a tube that inflates the bag is a no-brainer. It's simple, it gets the job done, and it doesn't change your buoyancy at all while you're doing it. That's how everyone I know inflates the little 1-meter SMB's.

For larger bags, it depends on the bag. I own a semi-closed ... which means there's a flap at the bottom of the bag with a one-way valve. You can hold your reg under the bag, hit the purge button for a couple seconds, and let it fly. Or you can hold the bag over your head and allow your exhaust bubbles to enter the flap, inflating the bag as you exhale ... you don't even need to take your reg out of your mouth to do that. I prefer the first option over the second because (a) it takes less time to inflate the bag that way, (b) I can see what I'm doing, and (c) exhaling into a bag that size usually requires more than one breath, which is going to change your buoyancy before you can let the bag fly.

... Bob (Grateful Diver)