Been to Koh Tao, should I go to PERHENTIANS?

Thus spake Stef <scuba@mostly-diving.REMOVE.co.uk> :

>morgand@cix.compulink.co.uk wrote in news:RPOdnerpRZz3wWrfRVnysw@pipex.net:
>
>
>> I dont know if there are any law's here in the UK ? Stef.......
>>
>HSE (Health and Safety Executive, for our overseas friends)
>http://www.hse.gov.uk/diving/
>have a huge say... as a government agency they can prosecute us (the
>divers) if we are acting in a professional capacity, or even suspected of
>operating in a professional capacity, and fail to meet our duty of care to
>fellow divers, snorkellers, swimmers, surfers etc.
>
>... before anybody picks on the word 'professional'...
>
>... this can affect any diver in the UK, risk management has become a way
>of life whether we like it or not.

Sorry, we tried to keep the trial lawyers from spreading, but it
sounds like they've infected the UK.

--
dillon

Linux, it's not just an OS, it's a way
of life.

And a damn fine one, at that.

In article <atehf15i0sfq292r9g12ajb02s2pre3uuh@4ax.com>,
dmpyronINVALID@austin.rr.com (Dillon Pyron) wrote:

>
> Sorry, we tried to keep the trial lawyers from spreading, but it
> sounds like they've infected the UK.

They have indeed, leaches.........

Dave Morgan @ Work in the UK
Take out the "goes diving" bit....
Trip photos on line at www.morg.co.uk

Dave Morgan <morgand@cix.compulink.co.uk> wrote:
> SPAMTRAPglawackus@hvc.rr.com (Steve) wrote:
> >
> > The "rules" on ppO2 are somewhat like the legislated speed limit, but
> > less arbitrary. Sticking to a ppO2 of 1.4 will result in most divers
> > being very safe on most dives. It's not an absolute guarantee, but it's
> > a lot better than what you get with a speed limit.
>
> So it IS a SAFE limit.......it IS safer than using PP02 1.6


Yes, 1.4 is safer than 1.6 for the same given time-exposure.

However, if you dive both of them to their "time limits", the risk is
effectively the same.

For example the maximum permissible exposure for 1.6 is IIRC 45 minutes,
and for 1.4 is IIRC 110<?> minutes.


The effective "safety" (1/risk) is the same because these MPE's were set
based on the same basic risk criteria. Simplistically, a single tank
dive on 1.4 is safer than 1.6 because its expected duration is not going
to approach (or exceed) this risk-based time limit...but for each at
their respective time limits, the risks should be around the same.


FWIW, here's some info from a very, VERY dated (1977) source that
references US Navy Tables for Pure O2 Depth-Time limits from that era:

Pure O2 on working dives:

Normal Operations:
depth (ft) time (min)
10 240
15 150
20 110
25 75

Exceptional Operations:
30 45
35 25
40 10

(Source: "The Complete Underwater Diving Manual" ISBN 0-679-50774-4
also referred to as the NOAA diving manual, 1977 edition).

[Note: all disclaimers apply - - this is exclusively for illustration
of this time/PPO2/risk variable from a historical reference source, and
not use for contemporary diving]




If we take the above source data (although very dated) and convert the
depths using pure O2 into representative PPO2 values to examine the time
limit trends, we get the following:

depth (ft) time (min) PPO2
10 240 1.30
15 150 1.45
20 110 1.61
25 75 1.76

30 45 1.91
35 25 2.06
40 10 2.21

[reminder: historical information for reference, not for diving]



Since the limit for 1.6 today is IIRC considered to be 45 minutes, but
30 years ago, the 45 minute limit was 1.9, what has changed?

Certainly not the human physiology.

More likely, the limit has changed either because our understanding of
the risks is now more complete (ie, we corrected the numbers)...

....or we've changed to a lower risk tolerance (ie, the numbers were
correct, but we changed our criteria for applying them).


In any event, what this shows is that all PPO2's have a safety limit,
and how close you approach the risk level that the said limit represents
will depend on the dive plan. And naturally, its not a step function
where the risk is zero at one minute short of the limit, and so forth.


-hh

In article
<{NOSPAM-rm_to_reply}rec-scuba2005-69FAC6.08352611082005@news.giganews.com
>, {NOSPAM-rm_to_reply}rec-scuba2005@huntzinger.com (H Huntzinger) wrote:

>
>
> In any event, what this shows is that all PPO2's have a safety limit,
> and how close you approach the risk level that the said limit
> represents will depend on the dive plan. And naturally, its not a step
> function where the risk is zero at one minute short of the limit, and
> so forth.

Yes, it starts the minute you get in the water.......
I'm indebted to you for that, thank you.

As i have said previously, i dont claim to have remembered everything that
has been said but i get the gist of what you say and my diving is all the
more safe for it.

Dave Morgan @ Work in the UK
Take out the "goes diving" bit....
Trip photos on line at www.morg.co.uk

> Lee appeared to imply that in the US there WAS/IS legislation.

I think you misunderstood me. In the US, the Dive industry is self
regulated. While there are laws for the protection of workers that include
working divers, they do not apply to recreational divers.

Lee