Full-face masks

[ferretchen]

I've heard all kinds of sales talk about why full-face masks are better. I believe that they are better when using communications, but I've never seen anyone mention safety.

It seems to me that any diver becoming unconscious underwater will drown with a normal mask, but with a full-face mask the diver has at least a chance to recover or get rescued. Given the number of fatality reports I've read where the diver has lost consciousness (cardiac event, stroke, oxygen toxicity, etc.) and then drowned, full-face masks seem like a good idea. If the regulator is attached to your face, and you can breathe through either nose or mouth whether conscious or not, doesn't this make you more safe?

Thoughts?

 

[DA Aquamaster]

Yes and no.

It's true that a diver with a full face mask is not going to spit out the mouthpiece and drown in the event he or she convulses or becomes unconcious.

But the other side of the equation is that using a FFM requires more training in the event you have an equipment failure. For example switching to an alternate air source in most cases requires removing your mask and donning a backup mask. It adds a level of complication to the other wise fairly straight forward procedure of using your buddy's octo.

There are other ways to access alternate air sources but they have donwsides.

Multiple regs on multiple ports on the mask add more hoses and create a very non standard configuration. A gas block can allow you to access two separate cylinders or first stages, but again it requires very thorough training to ensure you know what you are doing and it does not protect against a second stage failure.

Most FFM's are designed for commercial, public safety diving and/or surface supplied gas operations and are far less than ideal for recreational use, especially if they are set up for positive pressure operation where gas consumption can be substantially higher.


The Kirby Morgan KM-48 and its various clones are designed to incorporate a detachable pod that can be removed to access another second stage on a deco botte, pony bottle or buddy's alternate air source without requiring you to remove the mask. Its a better choice for recreational diving.

 

[mntdiver]

Ferretchen,

You've pretty much nailed it. Analyze many accident reports and you see a fairly common thread: "found on the bottom, apparently unconscious with regulator out of mouth". Think of arguments against seatbelts (stuck in a burning car, wrinkle my cloths), helmets (limit my field of view, mess up my hair) or other safety equipment and you'll see similarities. If, for whatever reason a diver might go unconscious underwater, with a full face mask, at least you'll have some opportunity for survival. With a bite mouthpiece, there are two threads on here where we can pretty much address the incident. "Passings" and "Accidents and Incidents".

Do they take additional training, practice and planning? You betcha, that's the nature of diving. I ran out of air once in 1979, haven't done it since, yet, I still plan on it. Add communications and I would say that a properly equipped and trained full face mask diver will be one of the safest divers in the water. This brings up another common thread in many diving related accidents: "Divers became separated". Once this happens, you have zero communications. Hand signals no longer work. What do you do now? Look for a minute or two and then meet on the surface... Right...

If you don't dive a full face mask, research what's available and talk to people that use them, not just sales people. Maybe I should say, especially not sales people.

 

[Otter]

...snip...set up for positive pressure operation where gas consumption can be substantially higher....

How does positive pressure operation cause higher gas consumption. Does it constantly leak around the face?