Why the choice of oral inflate SMBs?

[Tortuga68]

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?

/sigh

Read my post #37. There's a difference between exhaling/blowing bubbles, and inflating an SMB which leaves you with little to no air left in your lungs. You Lynne are the one who said earlier that switching regs to use your primary to purge inflate an SMB was "task loading" and my point, again, is that removing your reg from your mouth to oral inflate is no less task loading, and also that it creates a potential situation where a student is out of breath with no reg in their mouth which, again, is something that was stressed during my GUE-F course as a situation that should not occur i.e. during the valve shutdown drill you are instructed to only close one valve and then reopen it to avoid potential loss of breathing gas.

i imagine during your fundamentals, Gideon had you use all kinds of smbs

No. We did SMB deployment in the water a total of 1 time, with a 1.1m Halcyon oral inflate SMB. It's in my class report.


I don't know if you guys are deliberately misunderstanding what I say or if you just don't read my posts before replying. Either way, you've worn me down and I give up.

 

[LiteHedded]

I get what you're saying dude. You think exhaling a whole breathe into an smb for a second creates a potentially dangerous scenario and I simply disagree.

Let go of the bag and put a reg in your mouth. You will have AT LEAST two of them not counting your buddy

 

[kdupreez]

+1 on what Lynne and others said..

When I teach GUE Fundamentals classes, I require a orally inflatable, small enough to fit in your pocket type of SMB.

We (GUE) believe in you dive like you train and you train like you dive.. And here in the PNW, 99% of the diving done is done with 1.1m (3.3ft) smb's

When teaching and performorming an oral inflation of an smb, they key is not to blow every last little bit of gas in your lungs into the SMB.. remember, even at 33ft (10m) that SMB gas volume will double on the way up, so you really dont need a lot in the small SMB's at all.. maybe half of a normal breath..

All you are doing is displacing some of the gas in your lungs into the SMB, so you have NO change in bouyancy.. you also have VERY fine control over how much gas goes into the SMB.

You have the reg in your right hand and the SMB+Spool in the left hand.. if you feel like taking a breath, pop the reg back in, purge with the button and breathe.. you ALWAYS have control over the primary reg and SMB+Spool in that fashion.. put the reg back in your mouth, extend the spool and smb away from you, put the smb in your right hand and release...

so, we teach this small orally inflatable style for use during fundies when people initially learn the skill.. In my experience, the bigger bags and purge-to-inflate style are a pain in the ass for students to manage..

I have 4 of these halcyon 1.1m SMB's in my dive bag and without fail, so far every student in my fundamentals classes who did NOT have one of these, fudged their SMB deployments, used one of my spares and bought one right after class..

Purging regulators into bags from your long hose is not a good idea.. holding regs upside down and pressing the purge button is in my experience almost a guaranteed freeflow or semi freeflow. You dont have much control over fine lift management when using these.. And you cant "displace" the gas from your lungs into a bag.. you now have additional extra buoyancy you have to manage too..

Everytime so far when students tried that to prove a point with the bigger purge-to-inflate bags, they either ended up with the bag on the surface or they lost the bag due to over inflation..

Trying to purge a reg into a SMB while holding the SMB and spool with one hand and then trying to switch regs back with a now quite buoyant SMB and full hands is quite entertaining clster F@#$ to watch..

That said, lift bags are used with purge or no-lock power inflator nipples, I have quite a few of them and have used them with off-board gas.. orally inflating 100lb of lift at 150ft is also quite entertaining.. (I have video of that on a Tec2 class)

Anyhow. do what you like and what makes sense to you. But in my experience teaching GUE classes, the 1.1m Halcyon SMB's are worth their weight in gold..