Pros & Cons of Using a Full Face Mask
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DeepSeaExplorer
Contributor
Use more gas and CO2 headaches if you don't keep the mask clear.
If you choose to use a FFM for tech diving, expect to do a lot of solo diving...
If you choose to use a FFM for tech diving, expect to do a lot of solo diving...
I switched to a Kirby-Morgan KM-48 FFM for some of the reasons described above.
1. It has a detachable lower pod, so switching to an alternate regulator is a matter of detaching the lower pod (a quick one handed process) and putting the alternate reg in your mouth. If you do technical diving with stage or deco bottles and need a FFM, this is the way to go as it avoids the need to switch to a back up mask. Switching masks while hanging on a deco line in a 2 kt current at 120' is on the "things that are less than fun" list.
2. The separate oral cavity in the mask is already suitably small to limit CO2 retention, but to facilitate flooding and dewatering the lower pod prior to and after pod removal, it also has a mouth piece. This also means in very hard working situations you can use the mouthpiece and have no more CO2 retention than with a conventional regulator.
3. The mouthpiece also means an OOG diver can also breathe off the reg on the detached pod so you can put it on a long hose, or keep it short hosed and clip a long hosed backup to your harness.
4. Additional pods are available so if you need com capability or are in extremely cold water during deco, you can add a pod(s) to your deco reg(s). Since the com equipment remains attached to the mask not the pod, no extra com eqipment is required.
5. Overall bouyancy is minimal - much less obnoxious than a non-weight kitted AGA - as the mask is fairly low volume by FFM standards.
6. Cost is not outrageous (by recreational standards) as are Kirby Morgan's band masks and helmets and is less expensive than many other recreational FFM's.
7. You can use the regulator of your choice as the mask zip ties to the reg like any other mouthpiece would. This means you pay only for the mask and do not get stuck having to use whatever second stage the compnay puts on. This saves some money upfront and makes servicing much less complicated.
8. A rebreather pod is available (but last I heard still a little hard to get) so if you go that route, the KM-48 will work where most others will not.
One potential downside is that it operates much like a conventional mask in that your nose is in the upper portion of the mask so breathing through your nose is not an option as it is with most other FFM's. This also means that defogging is the same as with a conventional mask as no gas passes over the lens. On the other hand, this "downside" also means that the KM-48 operates much like a conventional mask (including clearing your ears) so the learning curve is quite short compared to other FFM's.
Another potential downside is that the mask is not suitable for contaminated water opeations, so if you like to dive at the local nuclear power plant, heap leaching pond or sewage lagoon, this is not the mask for you.
For rec/tech use I will put mine on a short hose (the only exception I have to the "donate the long hose primary" philosophy as with an FFM you do not normally get mugged for your primary and with the KM-48 the average buddy of the day is not going to know how to detach the pod or want to take the time to do that. In a technical situation, it is not DIR, but it is more practical for an OOG buddy to breathe off a regular mouthiece on the long hose reg. And all he or she has to do is tug it loose from the harness.
In some commerical situations with a bailout bottle, I will use it with an M&J Industries gas block on the waist strap near the light cannister and use a 42" hose from the block up and around the neck in normal long hose fashion. It keeps the hose routing clean and keeps the pod under control but readily available if I remove it on the surface. Gas blocks (IMHO) need to be very easy to identify switch position by feel and some of the available blocks do not cut it in my opinion in this regard.
All of this said, I still feel that a FFM has a very specific purpose and when that purpose is not required, the FFM brings nothing to the dive and needs to stay in the dive bag while you revert to a conventional mask for that dive.
1. It has a detachable lower pod, so switching to an alternate regulator is a matter of detaching the lower pod (a quick one handed process) and putting the alternate reg in your mouth. If you do technical diving with stage or deco bottles and need a FFM, this is the way to go as it avoids the need to switch to a back up mask. Switching masks while hanging on a deco line in a 2 kt current at 120' is on the "things that are less than fun" list.
2. The separate oral cavity in the mask is already suitably small to limit CO2 retention, but to facilitate flooding and dewatering the lower pod prior to and after pod removal, it also has a mouth piece. This also means in very hard working situations you can use the mouthpiece and have no more CO2 retention than with a conventional regulator.
3. The mouthpiece also means an OOG diver can also breathe off the reg on the detached pod so you can put it on a long hose, or keep it short hosed and clip a long hosed backup to your harness.
4. Additional pods are available so if you need com capability or are in extremely cold water during deco, you can add a pod(s) to your deco reg(s). Since the com equipment remains attached to the mask not the pod, no extra com eqipment is required.
5. Overall bouyancy is minimal - much less obnoxious than a non-weight kitted AGA - as the mask is fairly low volume by FFM standards.
6. Cost is not outrageous (by recreational standards) as are Kirby Morgan's band masks and helmets and is less expensive than many other recreational FFM's.
7. You can use the regulator of your choice as the mask zip ties to the reg like any other mouthpiece would. This means you pay only for the mask and do not get stuck having to use whatever second stage the compnay puts on. This saves some money upfront and makes servicing much less complicated.
8. A rebreather pod is available (but last I heard still a little hard to get) so if you go that route, the KM-48 will work where most others will not.
One potential downside is that it operates much like a conventional mask in that your nose is in the upper portion of the mask so breathing through your nose is not an option as it is with most other FFM's. This also means that defogging is the same as with a conventional mask as no gas passes over the lens. On the other hand, this "downside" also means that the KM-48 operates much like a conventional mask (including clearing your ears) so the learning curve is quite short compared to other FFM's.
Another potential downside is that the mask is not suitable for contaminated water opeations, so if you like to dive at the local nuclear power plant, heap leaching pond or sewage lagoon, this is not the mask for you.
For rec/tech use I will put mine on a short hose (the only exception I have to the "donate the long hose primary" philosophy as with an FFM you do not normally get mugged for your primary and with the KM-48 the average buddy of the day is not going to know how to detach the pod or want to take the time to do that. In a technical situation, it is not DIR, but it is more practical for an OOG buddy to breathe off a regular mouthiece on the long hose reg. And all he or she has to do is tug it loose from the harness.
In some commerical situations with a bailout bottle, I will use it with an M&J Industries gas block on the waist strap near the light cannister and use a 42" hose from the block up and around the neck in normal long hose fashion. It keeps the hose routing clean and keeps the pod under control but readily available if I remove it on the surface. Gas blocks (IMHO) need to be very easy to identify switch position by feel and some of the available blocks do not cut it in my opinion in this regard.
All of this said, I still feel that a FFM has a very specific purpose and when that purpose is not required, the FFM brings nothing to the dive and needs to stay in the dive bag while you revert to a conventional mask for that dive.
Actually when you get accustomed to using a good full face mask, such as an AGA, you'll find that you don't use more gas. CO2 washout is excellent and not an issue. Some masks, this isn't the case, I don't use a ScubaPro FFM, but, I've heard of complaints of hypercapnia especially on deep dives where high PPCO2 becomes an issue.
jim T.
Guest
How usefull and dependable are the removable regulator pod types of FFMs? They don't seem to be in use as much as switch blocks or removal of FFM and substituting a spare half mask? It would seem to be the best/compromise answer but maybe not?
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DA, Have any pics of the Kirby Morgan?
- Messages
- 13,507
- Reaction score
- 10,175
- Location
- Port Orchard, Washington State
- # of dives
- 1000 - 2499
Threads merged.
This is the link to the OTS site.
http://www.oceantechnologysystems.com/mk48.shtml
The M-48 is made by Kirby Morgan but is also I think marketed by JMC Scuba through Oceanic.
In terms of reliability, I have never had a problem with the pod system or the mask. It has worked well with G250, X650 and R295 second stages.
http://www.oceantechnologysystems.com/mk48.shtml
The M-48 is made by Kirby Morgan but is also I think marketed by JMC Scuba through Oceanic.
In terms of reliability, I have never had a problem with the pod system or the mask. It has worked well with G250, X650 and R295 second stages.
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