Scubapro classic bc

[tight rope walker]

halemano, I'm having a hard time wrapping myself around something you said about the air 2. I've never done a scooter dive but it sounds like fun. Given the location of the diaphram in the air 2, basically in a vertical attitude the diaphram being on the bottom, unlike a conventional diaphram where the diaphram in a verticle attitude would be in the front, I' m having a hard time imagining that unit freeflowing, especiality as the water is flowing over it horizontilaly. Also in my case I've had mine de-tuned to prevent this from happening.

 

[Splash-X]

I've never had my AIR2 freeflow when swimming against strong currents (similar to the effect of a scooter crusing).

The most common issue with the AIR2 is improper cleaning/post dive maintance which leaves salt, sand or other particles in the AIR2 which causes a free flow when you turn it on and go to take a breath to test it on the surface. I've see this happen on several occasions and 90% of the time it is on the surface prior to the dive.

 

[MauiScubaSteve]

halemano, I'm having a hard time wrapping myself around something you said about the air 2. I've never done a scooter dive but it sounds like fun. Given the location of the diaphram in the air 2, basically in a vertical attitude the diaphram being on the bottom, unlike a conventional diaphram where the diaphram in a verticle attitude would be in the front, I' m having a hard time imagining that unit freeflowing, especiality as the water is flowing over it horizontilaly. Also in my case I've had mine de-tuned to prevent this from happening.

I've never had my AIR2 freeflow when swimming against strong currents (similar to the effect of a scooter crusing).

With the scooters I have used/guided (4 employers - Apollo/Dacor - hundreds of dives including DPV Specialty) if you are advanced enough to "superman" the water speed across the reg is similar to diving in +2 knot current, but my past employers have had the trigger lock disabled so customers can not lock the trigger (I know a work around). The older models do not have auto disengage cords and if you let go it will go way faster than 2.5 knots until it runs into the bottom (lost/broken).

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The above photo's show the "superman" position; the handle on the bottom has the trigger so you have to reach down there to disengage the trigger. The photo below shows the "intended" operation, and an Air2 or similar hangs right at the cowling of the props. IMHO it does not matter if it is either in front or behind the blades as the water speed in that vicinity is way in excess of 2.5 knots and massive free flow is common. Combine that with the "noise" of scootering and a wireless integrated computer, which does not communicate when the electric scooter motor is running, and you have a "perfect storm."

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[tight rope walker]

Once again, in a horizontal attitude, the air 2 hangs against your bc with the diaphram failing towards your feet. In this attitude the water would not hit the face of the diaphram. And as your pictures show in the superman position, you are basically in a horizontal attitude, infact all the divers wether in superman or not, are in a horizontal attitute in the water column. Once again if you are moving forward and the flow of water is moving past you, and the diaphram is basically pointing towards your feet on the air 2, I donot believe it is the flow of water that is making the air 2 leak. Maybe it is something else. But if that were the case a simple adjustment would remedy that problem. I think another simple solution would be, if there is enough hose, to stick the air 2 inside the vest, to shield it from the water flow. This might be another question for tech services....HA HA HA!

 

[Splash-X]

Good information halemano.

I think what is happening is the force of the water being pushed from the blades is creating some sort of "suction" accross the mouth of the AIR2 which would simulate breathing. I could be totaly wrong but thats my best guess.

 

[tight rope walker]

That's a very good point splash. For a while I thought that maybe the prop wash hit the diver in the chest than bounced back and hit the diaphram. Once again I believe a simple adjustment would correct this problem.

 

[MauiScubaSteve]

Good information halemano.

I think what is happening is the force of the water being pushed from the blades is creating some sort of "suction" accross the mouth of the AIR2 which would simulate breathing. I could be totaly wrong but thats my best guess.

You are correct, just as turning a second stage towards the surface causes free flow (pressure differential). Whatever anyone else wants to think, I have seen the mouthpiece "caught" on the front of the cowling and blowing furiously through the prop, as well as mouthpiece dangling behind in the prop wash and similarly blowing furiously, on nearly every Air2 user I've ever scooter guided.

The relaxed scooter body position is more inclined than horizontal, but either way the Air2 or similar is not also horizontal; it is hanging down away from the chest. You can flex more muscles and orient your body to be parallel to the scooter, just above the plane of the scooter, but with more muscles flexed and possibly more frontal drag, the benefits of scooters are significantly negated, and again the Air2 "dangles."

 

[tight rope walker]

If that is the case, and I donot doubt you, wouldn't your main reg freeflow also,as the flow of water hits the diaphram head on?

 

[MauiScubaSteve]

That's a very good point splash. For a while I thought that maybe the prop wash hit the diver in the chest than bounced back and hit the diaphram. Once again I believe a simple adjustment would correct this problem.

If you crank the Air2 down to where it will not free flow in these conditions it will be really hard to get a breath off it; it is not just a simple adjustment IMHO. I am not able to use my Oceanic Zeta on a scooter dive because it is a "high" flow second and not adjustable on the fly, whereas my Delta 4 and EOS can be cranked down on the fly. If the Air2 had that kind of manual adjustment knob, which turns the flow down to "not enough to breath", you might have a solution, until an OOA buddy grabs your primary and you had forgotten to turn it back up.

 

[MauiScubaSteve]

If that is the case, and I donot doubt you, wouldn't your main reg freeflow also,as the flow of water hits the diaphram head on?

Your mouth on the mouthpiece and the act of breathing in and out helps to negate this pressure differential, but a "loosely" tuned second does sometimes free flow and if you turn your head to the side to check on your buddy many "properly" adjusted seconds do indeed free flow some also.