http://www.oceantechnologysystems.com/mk48.shtml
This is the same mask that you may have seen Cousteau's team wear on the recent PBS underwater series (though his team's are blue, and mine is black).
I'm wearing it in the avatar picture. Here's another image:
This mask system is unique -- it is a full face mask, but unlike other FFMs, it is possible to use this mask with DIR-style procedures.
The mask is essentially divided into two compartments; a standard 'low profile' mask compartment for your eyes & nose, and the "Pod" compartment for your regulator. The Pod is detachable, and when removed, your eyes & nose remain free of water. The secondary regulator can be held in the mouth with a standard-shaped mouthpiece, or you can let it sit just in front of your mouth, allowing you to breathe and speak normally.
I have attached my normal G250 second stage regulator to the Pod. The attachment required nothing other than the mouthpiece extender supplied by KM, and a zip-tie. I use the same bolt-snap I placed on my long-hose when diving with a normal mask, and clip & unclip the pod without any problems.
In the event of an OOA emergency, I would remove the Pod and donate the hose to my buddy. Removal of the Pod can be done with the right hand alone, and the motion to unclip the Pod and present the regulator is little different than the process used with a standard second stage.
Once opened, the mask has more than enough room to easily insert the backup regulator, and I have been able to grab the reg with just my mouth and perform a no-hands switch (potentially handy in certain kinds of emergencies).
Because the regulator is attached with a simple zip tie, which I keep only moderately tight, the second stage will separate from the mouthpiece & the Pod in the event that a diver were to yank it out of my mouth without doing an OOA drill. Also, the Pod is designed to "fail open" - a hard, rapid jerk on the Pod causes it to fall away from the mask. Worst case scenario, an OOA diver gets a reg without a mouthpiece, which is surprising, but far from lethal.
When I first began diving the mask I had a lot of problems with flooding the Pod portion. I finally figured out that unlike my Neptune II NIRA FFM, the Mk48 has a manual purge valve which must be depressed to allow water to drain from the Pod while submerged. Once I understood the correct procedure, a little practice with the tilt of my head and the placement of my hand to activate the purge cleared up that problem, and I now am able to dump the water quickly & easily.
I also found that I had problems with the fit of the mask, with the upper portion feeling "tight" around my eyebrows. I had originally been donning the mask with its webbing unclipped, then clipping the webbing, then tightening the straps. I think that the difficulty of doing this while standing in the surf surge, and often holding my fins was causing me to mis-align the straps and mis-tighten the webbing. Recently I found a much better method. I open the webbing to its maximum extension, clip it shut, then don the mask. Once it is on, I tighten the straps and achieve a perfect fit. No more problems. I have also practiced this maneuver while submerged with success, so I consider the problem resolved.
So why dive the mask in the first place?
Primarily, I like it for the improvement in communication. My dive team members are great divers, and 90% of the time we have good team & situational awareness. But we're diving for fun, and every once and a while someone goes walkabout, or gets confused as to the plan, or just needs to be told what the heck the team is looking at. Hand signals can deal with some of these issues, but I sure like the ability to just clearly say what I want to say and be understood.
Example: Two weekends ago, Sounder joined our dive team of myself and DiverC at Redondo. After our descent to the thick line, Sounder's main light failed. I tried to re-strike it, with no success. Pre-dive, both Sounder and I had talked about how we prefer to abort dives when compromised by equipment failures.
On this particular dive, we had great viz, and lots of ambient light, and Sounder had his backup light equipped and ready to deploy. I felt that there was no significant danger and that the dive had not been compromised, but Sounder was the diver with the problem, and I felt the decision was up to him. Under other circumstances, we may have had a confusing time trying to discuss our options and make a go/no-go decision. But since I was wearing the Mk48, I just asked him (showing him the hand signs thumb-up and thumb-down to be clear) "do you want to abort, or continue?" He responded thumb-down "go", and we exchanged "oks", and continued the dive.
Another example: Our team of myself, DiverC, and BubbleMkr were diving on the Maury Island site. We were looking for the rock pile, which we have been on before but have failed to find on several subsequent attempts. We descended to 70fsw, and commenced our search. At a certain point, I decided that we needed to reverse direction and go up-slope. Again, this change in plan could have been handled with hand signals, but it was so much easier to just tell the team what I wanted to do, and why, and get their "oks". No confusion, and good communication.
Note: I'm not using an underwater communications device -- I'm just speaking normally into the air-filled Pod. My team reports that I can be heard clearly and distinctly up to several feet away.
Long term, I see several other benefits to the mask. I could outfit it with a true underwater comms system if I wished. I think underwater comms could come in handy in a variety of situations, from training, to doing surveys, to "work" at depth, etc.
When I am ready to move into multi-gas deco diving, I see the mask as an added safety factor when using high O2 mixtures. In the event (unlikely as it may be) of an OxTox, the Mk48 will keep my breathing passage free of water, and may be the difference between life & death.
I also find that the mask keeps my face warmer than a traditional half-mask. A significant amount of heat is lost through the head & face, and the air in the Pod acts as a kind of insulator to help reduce that heat exchange with the cold water. It is hard to quantify, but I feel much warmer diving with the FFM than without it.
On 3 occasions I have had my normal half-mask kicked off my face by my dive team. That's just no fun, even though I'm proficient in the necessary skills to replace it quickly and without much other disruption. Twice since I started wearing the Mk48 I have taken a fin to the face, and in both occasions, the mask remained in place, rock solid. I have high confidence that it will do so under a wide range of potential snags, blows, and inadvertent fin kicks.
In the past I have used a Neptune II NIRA FFM, and found that one of the disadvantages of the mask was the large air pocket it creates, which had a substantial effect on my buoyancy, and required me to carry several extra pounds of weight to counteract. The Mk48 keeps this air pocket to a minimum, and I have not noticed any need to change weighting on my rig between normal half-mask diving and Mk48 diving.
There is a local Kirby Morgan dealer in Seattle, who provided me with a replacement long mouthpiece after I acquired my mask. I was very happy with their service & responsiveness.
http://www.divecommercial.com/
I'd be happy to answer any questions the club might have about the mask and my experience diving it.
