What back-up tables?

[The Iceni]

Dr Deco once bubbled...
Dear Readers:

PFO and DCS

Regarding the PFO question, it is good to recognize that several conditions are necessary for a PFO to result in DCS.

• a HEMODYNAMICALLY significant shunt (see attachment)
• many venous-return gas bubbles,
• some type of Valsalva-like maneuver,
• adequate “rebound flow” (position dependent)

Dr Deco :doctor:

Ha! I think this may explain why these incident rates vary so much.

Even with a haemodynamically significant shunt it would seem DCI can be avoided with.

1 Good ascent (decompression) practices.

2 No Valsalva manoeuvres during the ascent and post dive.

3 Position is irrelevant when submerged (no gravitational effects). Not to be confused with chamber decompression.

I still feel the investigation will be very useful to prove this in recreational divers.

 

[ColdH2Odvr]

Nikjb,

If you’re getting into deco on your computer, stop. It’s time for more training.

 

[Alban]

Excuse me from bring back up the points about a spare mask ( which I do agree with ) but many of the accidents involving masks can be avoided , I have clipped the straps on my mask so it will not become loose or undone also I wear it under the hood so there is no danger of loosing it , obviously it is still wise to carry a spare.

Yours Alban

 

[nickjb]

I did a few mask-off, mid-water exercises. I could maintain position if I had a good reference point (Buddy, large object) but I couldn't read my depth or contents guage. A spare mask seems like a must buy.
.

 

[padiscubapro]

Alban once bubbled...
Excuse me from bring back up the points about a spare mask ( which I do agree with ) but many of the accidents involving masks can be avoided , I have clipped the straps on my mask so it will not become loose or undone also I wear it under the hood so there is no danger of loosing it , obviously it is still wise to carry a spare.

Yours Alban

You still don't account for a mask failure.. Its unlikely but I HAVE seen masks damaged by other careless divers..

Will you mask stay on if the strap is broken??..

say you don't lose the mask, but you break the strap, and you are in a strong current which mandates you stay in contact with an ascent line, you now have to manage

a) keeping mask in place (you are in a current)
b) contact with line or if you shoot a bank, you wll have to do this which isn't easy one handed then keep contact.. try reeling in a bank with 1 hand... it can be done but... do you want to do it?
c) buoyancy
d) gas switches (turning on, stowing or freeing and shutting regs)
e) depth and time

If you have to keep the mask in place you effectively lose on hand.. how are you going to do the others???

a second mask sound like a worthwile investment to me....

 

[Alban]

Dear Padiscubapro
I may not have explained myself fully
I was not suggesting these were alternatives to carrying a spare mask I did say " Excuse me from bring back up the points about a spare mask ( which I do agree with ) "

A lot of divers wear their mask outside of their hood . It can easily be knocked or pushed off the head this can easily be avoided by wearing it under the hood . I have seen straps come undone this also can be avoided . The strap may break as you suggest I agree it may but this is most likely to happen when putting the mask on or off. The mask could spring a leak ,if it happened on the ascent and was manageable I would continue until an extended stop to switch masks.

I looked at the problems from a proactive view to see if any of the scenarios could be avoided in my opinion some can but not all as I said "obviously it is still wise to carry a spare."

Apologies for my quoting I haven't got the hang of that yet

Yours Alban

 

[O-ring]

I don't see a problem with this unless your mask strap (I use a thick neoprene one) causes your hood to leak and causes thermal protection to be compromised. I have never tried wearing mine under the hood, but I bet if I did under my DUI hood my head would freeze from the water coming in where the velcro straps would now be holding the area of the hood that seals to my face wide open.

If yours doesn't cause this, I don't see a problem...as for me, I ordered a spare mask because I don't think wearing my mask under my hood works for me.

 

[padiscubapro]

O-ring once bubbled...
I don't see a problem with this unless your mask strap (I use a thick neoprene one) causes your hood to leak and causes thermal protection to be compromised. I have never tried wearing mine under the hood, but I bet if I did under my DUI hood my head would freeze from the water coming in where the velcro straps would now be holding the area of the hood that seals to my face wide open.

If yours doesn't cause this, I don't see a problem...as for me, I ordered a spare mask because I don't think wearing my mask under my hood works for me.

Oring
In the NY area many divers wear the strap under the hood, it does help prevent knock offs... This works for un attached hoods where a little h20 doesnt make a bit of differe
nce, but f you are using an attched hood where its part of your drysuit seal, that wouldn't be a good thing....

Alban I wasn't attacking you, Just trying to bring up more points for thought.. The problem is too many divers get in over their head (no pun intended) and start doing dives they are untrained for and don't ever think of the consequences..
Locally this year we had 1 near death (the diver was technically dead), the person did not have the training or experience for the dive he was doing (he was solo diving).. He was found entangled, unconscious and no reg in mouth by one of the other divers on the boat.. He was brought to the surface, revived, evacuated by helicopter and needed several chamber treatments. This was a 17 year old diver who ended up having damage to his brain.. he has made almost a full recovery, but will never be able to dive again.
Technical diving properly executed is probably (overall) safer than your simple recreational dive becuase you plan for everything(or at least try to)..
The mask is a simple item, yet most people overlook its importance in the scope of things..

 

[O-ring]

PSP,
Makes sense to me, just pointing out that in some cases that might suck depending on your exposure suit setup. My hood came with an MCS, but it looked pretty kludgy and I didn't want to try to install it (see pic).

 

[Alban]

:argue:

All agreed then , sorry to hear of the boy and something that could have been avoided , I was on a boat earlier this year when a girl was lifted off ( 5 hours in the chamber ) again diving beyond her limitations there were a number of errors but one thing was her computer had put her into deco and she didn't know what the "New " numbers where on the screen !

yours Alban