Article in March 2006 issue of Scuba Diving

Theoretically all dive have almost all dives have a degree of nitroigen
supersaturation. With any degree of supersaturation there is always a
risk of bubble nucleation. The dive tables are based on what chance
there is of a large bubble nucleation. Being on safe time does not mean
no bend. However in safe time means the risk of nucleation of a bubble
and the size of the bubble are PROBABLY within an acceptable limit.
One of the biggest risks to bubble nucleation is a fall or bump after
getting out of the water. Think of the bang on the side of a bottle of
coke.
The effect of a bend depends where the bubble forms. In muscle tissue
leave it any decompression risks the bubble moving to a more sensitive
area. Better to be live with a small numb dead spot of muscle than a
cerebal bend.
Bob M

Theoretically all dive have almost all dives have a degree of nitroigen
supersaturation. With any degree of supersaturation there is always a
risk of bubble nucleation. The dive tables are based on what chance
there is of a large bubble nucleation. Being on safe time does not mean
no bend. However in safe time means the risk of nucleation of a bubble
and the size of the bubble are PROBABLY within an acceptable limit.
One of the biggest risks to bubble nucleation is a fall or bump after
getting out of the water. Think of the bang on the side of a bottle of
coke.
The effect of a bend depends where the bubble forms. In muscle tissue
leave it any decompression risks the bubble moving to a more sensitive
area. Better to be live with a small numb dead spot of muscle than a
cerebal bend.
Bob M

On 30 Apr 2006 13:36:39 -0700, "Bob M" <molab@ww.co.nz> wrote:

>One of the biggest risks to bubble nucleation is a fall or bump after
>getting out of the water. Think of the bang on the side of a bottle of
>coke.

Shit! I never thought of that.
Not much chance of avoiding that on a thirty or more mile return to
port in rough water.

On 30 Apr 2006 13:36:39 -0700, "Bob M" <molab@ww.co.nz> wrote:

>One of the biggest risks to bubble nucleation is a fall or bump after
>getting out of the water. Think of the bang on the side of a bottle of
>coke.

Shit! I never thought of that.
Not much chance of avoiding that on a thirty or more mile return to
port in rough water.

On 30 Apr 2006 13:36:39 -0700, "Bob M" <molab@ww.co.nz> wrote:

>One of the biggest risks to bubble nucleation is a fall or bump after
>getting out of the water. Think of the bang on the side of a bottle of
>coke.

Shit! I never thought of that.
Not much chance of avoiding that on a thirty or more mile return to
port in rough water.

sytech@yahoo.com wrote:
> The point the author makes is that "the trickiest part of your dive
> might come after the safety stop".

In theory yes - as the biggest pressure gradient occurs in the
shallowest few meters.

That being said, I dont think too many people are getting bent coming
up a bit too fast from 5m to the surface.. not on a single tank rec
dive, anyway. So calling it the "trickiest part of the dive" is, IMO,
overstating it - atleast by implication.

Vandit

sytech@yahoo.com wrote:
> The point the author makes is that "the trickiest part of your dive
> might come after the safety stop".

In theory yes - as the biggest pressure gradient occurs in the
shallowest few meters.

That being said, I dont think too many people are getting bent coming
up a bit too fast from 5m to the surface.. not on a single tank rec
dive, anyway. So calling it the "trickiest part of the dive" is, IMO,
overstating it - atleast by implication.

Vandit

sytech@yahoo.com wrote:
> The point the author makes is that "the trickiest part of your dive
> might come after the safety stop".

In theory yes - as the biggest pressure gradient occurs in the
shallowest few meters.

That being said, I dont think too many people are getting bent coming
up a bit too fast from 5m to the surface.. not on a single tank rec
dive, anyway. So calling it the "trickiest part of the dive" is, IMO,
overstating it - atleast by implication.

Vandit

mike gray wrote:
> When you ascend from, say, 99 fsw to 66 fsw the pressure change
> is from about 59 psi to about 44 psi, a one-quarter reduction
> which will result in a 25% expansion of the air in yer lungs.
>
> But when you ascend from, say, 33 fsw to the surface the
> pressure change is from about 29.4 psi to about 14.7 psi and the
> halving of pressure will double the volume of air in yer lungs
> in the same 33 feet of ascent.

Good grief... isnt life so much easier with "1 bar every 10m", as
opposed to "14.7psi every 33 ft"?

Am sending an OW student down your way to Splashdown, btw. If someone
is there, asking for you to learn more about DIR, blame me for that :)

V.

mike gray wrote:
> When you ascend from, say, 99 fsw to 66 fsw the pressure change
> is from about 59 psi to about 44 psi, a one-quarter reduction
> which will result in a 25% expansion of the air in yer lungs.
>
> But when you ascend from, say, 33 fsw to the surface the
> pressure change is from about 29.4 psi to about 14.7 psi and the
> halving of pressure will double the volume of air in yer lungs
> in the same 33 feet of ascent.

Good grief... isnt life so much easier with "1 bar every 10m", as
opposed to "14.7psi every 33 ft"?

Am sending an OW student down your way to Splashdown, btw. If someone
is there, asking for you to learn more about DIR, blame me for that :)

V.