unlimited dives shallower than 30 ft. min S.I.

[Spoon]

Hello Spoon:

You can make numerous dives of the type you mention, i.e., less than 30 fsw. There are many commercial divers who search for sea life, e.g., clams and such, who perform dives such as this every day.

Dr Deco :doctor:

thanks doc! thats all i needed to hear

 

[Spoon]

IN A DRY SUIT?

wetsuit.

 

[chip104]

More modern research suggests this is not always safe and the "unlimited" diving depth should probably be 15ft, meaning that a 1.5:1 pressure change is always safe.

You're gonna have to back that up with references.

 

[Dr Deco]

Hello chip104 and readers:

When SATURATION dives are made to shallow depths, the results of bubble detection and DCS are different. This is not the same as recreational scuba diving, however. The references to the long, shallow exposures are given below with the abstractes of the papers.

Dr Deco :doctor:



References :book3:

[1] Eckenhoff RG, Osborne SF, Parker JW, Bondi KR. Direct ascent from shallow air saturation exposures. Undersea Biomed Res. 1986 Sep;13(3):305-16.

Thirty-four healthy human subjects were exposed to shallow air saturation for 48
h [25.5 fsw, and 29.5 fsw] and then decompressed to 1 ATA (0 fsw) in about 2 min. Symptoms included fatigue, limb and joint pain, headache, myalgias, and pruritus. No subject of 19 was diagnosed as having decompression sickness (DCS) after the shallower exposure, but 4 of 15 were diagnosed and treated for DCS subsequent to the deeper exposure. Almost all subjects in both groups had Doppler-detectable venous gas emboli (VGE) lasting up to 12 h post decompression. This study indicates that hyperbaric air
exposures of this magnitude are not as benign as previously thought. {Abridged for this SCUBA BOARD forum}


[2] Eckenhoff RG, Olstad CS, Carrod G. Human dose-response relationship for decompression and endogenous bubble formation. J Appl Physiol. 1990 Sep;69(3):914-8.

The dose-response relationship for decompression magnitude and venous gas emboli
(VGE) formation in humans was examined. Pressure exposures of 12, 16, and 20.5 FSW were conducted in an underwater habitat for 48 h. The 111 human male volunteer subjects then ascended directly to the surface in less than 5 min and were monitored for VGE with a Doppler ultrasound device regular intervals for a 24-h period. No signs or symptoms consistent with decompression sickness occurred. However, a large incidence of VGE detection was noted. We conclude that the reduction in pressure necessary to produce bubbles in humans is much less than was previously thought; 50% of humans can be expected to generate endogenous bubbles after decompression from a steady-state pressure exposure of only 11 FSW. This may have significant implications for
decompression schedule formulation and for altitude exposures that are currently
considered benign. These results also imply that endogenous bubbles arise from
preexisting gas collections. {Abridged for this SCUBA BOARD forum}

 

[BarryNL]

You're gonna have to back that up with references.

Well, I basically quoted that from "Deep Diving" by Bret Gilliam

http://www.amazon.com/gp/product/09...4?v=glance&n=283155&n=507846&s=books&v=glance

 

[Dr Deco]

Bret Gilliam assuredly used the above-quoted works as his source.

 

[Diver0001]

Well, I basically quoted that from "Deep Diving" by Bret Gilliam

http://www.amazon.com/gp/product/09...4?v=glance&n=283155&n=507846&s=books&v=glance

And it should be noted for the record that much of what Bret Gilliam (aka Dread Gilligan) says shouldn't be quoted at all....He's done and said a lot of really off the wall things by todays standards....

@Jamdiver... those BASC tables are for air, right? Looks like it but it's best to be sure.

R..

 

[chip104]

Thanks for feeding my curiousity Barry and Doc!

 

[Jamdiver]

And it should be noted for the record that much of what Bret Gilliam (aka Dread Gilligan) says shouldn't be quoted at all....He's done and said a lot of really off the wall things by todays standards....

@Jamdiver... those BASC tables are for air, right? Looks like it but it's best to be sure.

R..

Yes it is, sorry I should have been clear about that.
Level 1 tables, i.e. Sea level to I believe a few hundred meters?

 

[chip104]

Hi Dr. Deco, just another question in relation to Spoon's.

For unlimited shallow diving, will poor air quality in the tank lead to increased VGE detection? Will it make you more suceptible to DCS?

Thanks for any insight!