2nd stage exhaust

[DA Aquamaster]

I don't know what type of reg you use, but could you perhaps simply take the exhaust tee off and zip tie a piece of tubing in its place, routing it to the back of your head like a snorkel?

This works well with older metal cased regs where the rubber tee pressed on over a cup shaped metal mount. It is not often an option with plastic cased second stages where the T is molded in or screwed on. And you still have the problem of how to secure the end of the hose behind your head.

The bubble interference problem is ironically greatly exacerbated today by the simultaneous increased popularity of smaller second stages (with commensurately smaller exhaust tees) and the increase in popularity and sales of smaller low volume masks.

Low volume masks make sense for freedivers as they have less volume to equalize on descent and consequently leave more air available in the diver's lungs for metabolic purposes. But there are really few if any advantages for scuba divers who relatively speaking have an unlimited volume of air available for clearing purposes. Rebreather divers arguably could benefit from smaller masks as any gas used for clearing a mask is sacrificed from the loop whihc impacts efficiency of the rebreather. But at the same time, like free divers, bubble interference is not a problem for rebreather divers.)

Smaller second stages while very popular, in my opinion, offer no advantage to a diver at all and unfortunately bring with them a couple of compromises, one of them being smaller exhaust Tees and more bubble interference. When you combine a small second stage with a low volume mask, you are going to have to accept a greater degree of bubble interference. (something the people pushing small second stages and masks never actually mention)

In the past, large masks were quite common and, for example, the Scubapro Tri-View and Tri-Vent masks used a lip on the underside of the mask designed to catch and deflect bubbles to the side. Nobody ever complained about bubble interfence with one of them as it did not occur unless you were looking straight up or were inverted.

What the Madison Avenue advertising types decide and then try to convince other people is cool and marketable more often than not does not represent progress when it comes to scuba equipment. With scuba equipment each piece has a specific function to perform and form must follow function, not the other way around.

 

[Creed]

This works well with older metal cased regs where the rubber tee pressed on over a cup shaped metal mount. It is not often an option with plastic cased second stages where the T is molded in or screwed on. And you still have the problem of how to secure the end of the hose behind your head.

I was envisioning essentially a snorkel attached to the 2nd stage. It would run up the side of the head, through a little loop attached to the mask strap, just like a snorkel.

 

[scubatoys]

I was envisioning essentially a snorkel attached to the 2nd stage. It would run up the side of the head, through a little loop attached to the mask strap, just like a snorkel.

I'm pretty sure you will find the WOB on the exhaust cycle of breathing would increase dramatically. How hard is it to clear a snorkel vs. exhale on a reg? How far you have to move the air is part of the reason.

 

[DA Aquamaster]

Larry's nailed that one on the head.

You would also be creating a situation where the remaning water in the "snorkel" will have water with a lot more head pressure to force its way around the exhaust valve. So the reg would breathe pretty wet in addition to having a high exhalation effort.

If you look at double hose reg exhaust hoses, you will note that they keep the exit at about the same level as the entrance and in addition they use a duckbill valve to keep water out of the exhaust end of the hose in addition to the mushroom exhaust check valve at the mouthpiece end of the hose.

If you ever use a doubel hose reg you will notice that the valves and lenght of the hose creates a very high exhalation effort compared to a single hose regulator.

 

[ranger979]

Low volume masks make sense for freedivers as they have less volume to equalize on descent and consequently leave more air available in the diver's lungs for metabolic purposes. But there are really few if any advantages for scuba divers who relatively speaking have an unlimited volume of air available for clearing purposes.

This is getting off track slightly, but isn't the one of the reasons for a low volume mask so mask is closer to your face and therefore you have an increased field of vision?

 

[pants!]

If the 'snorkel' that goes up from the exhaust tube did not bend downward and was sufficiently wide, there would be no increase in WOB. However, it would certainly be a huge pain in the butt to deal with and you would only be able to easily exhale when in a normal position... on your back would make it almost impossible.

 

[WarmWaterDiver]

Scubapro sells a Bubble Deflector for their small second stages, but I had to order mine from the UK. It's worked well. No USA Scubapro dealer I contacted even knew of the accessory, much less how to order one.

http://www.scubapro.co.uk/products.asp?P=470

 

[Creed]

I'm pretty sure you will find the WOB on the exhaust cycle of breathing would increase dramatically. How hard is it to clear a snorkel vs. exhale on a reg? How far you have to move the air is part of the reason.

Didn't think about that. I can envision a way around that, but now it becomes less of a simple solution to drbill's problem. I guess the simpler answer is buy a new Mistral or invest in vintage gear.

 

[spectrum]

My wife and I dive Sherwood Blizzards with the wide "walrus" exhaust Tee. If it were not for the sound of the bubbles I wouldn't know they were coming out.

Pete

 

[partridge]

I have to disagree on the "WOB using a long exhaust hose" argument. You are not trying to blow the air through the hose. I think I can have a 20 foot hose and have no problem. If the hose is filled with water then the air will rise on its own right? I can attach a small float to the top of the hose and it will keep it away from me. If I have any problems I just rip the hose off my exhaust. All hypothetical, of course, for all those who will jump on a safety issue.