On Thu, 11 Jan 2001 23:43:33 +1100, David Strike <[log in to unmask]>
wrote:
>On Thursday, January 11, 2001 11:34 PM, Mike wrote:
>
>(snip)
>> > Just use the ever popular, tried & tested 'hoist assisted inverted
>recovery
>> > procedure', not sure if this is a DAPI speciality module or not :-)
>> Uh.... what's a DAPI? ;-)
>
>I'm as intrigued as you are! :-)
>
>And on this high note, I'm away to my pit for some kip! :-)
>
>Strike
DAPI = Defrocked Association of Professional Instructors.
Its membership consists of those who have fallen off NAPI. Strike, I
am surprised that you're not familiar with NAPI or the NAPI Tables! :-)
NAPI
National Association of Professional Instructors
(c) Guido Zsilavecz
17 November 1994
The NAPI Safe Diving Principles:
Part 4: Drinking and Diving
Introduction
Lets face it: divers drink. Fish become bigger, depths deeper,
dives longer and sharks closer after a few drinks. The problem is
that diving after a heavy night of story telling is frowned upon
by most diving agencies. They have rules such as "12 hours flask
to mask", and others. Yet surely these rules are over simplified
and generalized? After all, one glass of wine and a crate of beer
are two different things, yet in each case one has to wait 12
hours before diving! Surely there must be a more scientific
approach to drinking and diving? NAPI decided to use the
scientific approach and investigated.
The Breaking Down of Alcohol
Investigations have shown that alcohol and nitrogen behave
similarly, in that both are removed over time from the tissues. As
is well known, going diving increases nitrogen levels rapidly, yet
it takes some time at the surface for the nitrogen to be
eliminated. Similarly, alcohol levels are increased rapidly by
drinking, and it also takes time for the alcohol levels to drop
once one stops drinking. Alcohol has the advantage over nitrogen
in that it is only broken down in one tissue; the liver. From
careful observations NAPI established that this break-down occurs
exponentially. If we take 12 hours as being the time needed to
clear the body of alcohol (as implied in the "12 hours flask to
mask" rule), and if it takes 6 time cycles for a tissue behaving
exponentially to clear, it becomes obvious that alcohol has a half
time of 2 hours.
Maximum Allowable Alcohol Levels
If most countries allow us to operate heavy machinery (that is,
drive cars) with a maximum of 0.08% alcohol in the blood, then
NAPI believes that 0.08% should be the limit for diving too. Thus,
it is not necessary to clear the body completely of alcohol, but
only enough to ensure that we do not exceed the legal level. With
these facts it is now possible to create a table for Alcohol
Breakdown.
The Alcohol Breakdown or Drinking Table
First, a few definitions: the tables use a common beer with 5%
alcohol as its unit. This corresponds to a glass of wine, or a tot
of spirits. We shall term this unit ALC, or Alcohol Loading
Content. Drinking between 2 and 3 ALC's is equivalent to about
0.08% alcohol. For simplicity, we shall assume that the diver may
safely drink up to 2 ALC's before reaching the legal limit, but if
more is drunk one has to wait for the alcohol to break down, that
is, wait until the equivalent of 2 ALC's remains. This waiting
time, as well as the time between drinks, is called SIT, or
Sobering-up Interval Time. After each SIT you still have a certain
amount of RAV in you. RAV (spoken "rave", of course), or Residual
ALC Value, is the remaining alcohol which has not been broken down
yet.
Now lets look at the tables.
Table 1 shows the SIT to clear, that is, reach the legal limit,
relative to your current ALC value. Always round ALC's up, for
added safety. There is no SIT required up to 2 ALC's.
Table 2 shows the RAV left in you after a certain SIT, starting
with a certain ALC level.
Remember to always go to the next higher level if on a boundary!
Table 1: Time To Clear
ALC Level
| 0->2 | 2->3 | 3->4 | 4->5 | 5->6 | 6->7 | 7->8 | 8->9 | 9->10|
|------+------+------+------+------+------+------+------+------|
| 0:00 | 1:10 | 2:00 | 2:38 | 3:10 | 3:36 | 4:00 | 4:20 | 4:38 |
SIT to Legally Clear in hours:minutes
Table 2: RAV levels
\SIT| A | B | C | D | E | F | G |
\ | 0 -> | 30 -> | 1 -> | 2 -> | 4 -> | 8 -> | > 12 |
ALC\| 30min | 60min | 2 hrs | 4 hrs | 8 hrs | 12 hrs | hrs |
----+-------+-------+-------+-------+-------+--------+-------|
1 | 0.8 | 0.7 | 0.5 | 0.3 | 0.1 | 0.0 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
2 | 1.7 | 1.4 | 1.0 | 0.5 | 0.1 | 0.0 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
3 | 2.5 | 2.1 | 1.5 | 0.8 | 0.2 | 0.0 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
4 | 3.4 | 2.8 | 2.0 | 1.0 | 0.3 | 0.1 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
5 | 4.2 | 3.5 | 2.5 | 1.3 | 0.3 | 0.1 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
6 | 5.0 | 4.2 | 3.0 | 1.5 | 0.4 | 0.1 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
7 | 5.9 | 5.0 | 3.5 | 1.8 | 0.4 | 0.1 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
8 | 6.7 | 5.7 | 4.0 | 2.0 | 0.5 | 0.1 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
9 | 7.6 | 6.4 | 4.5 | 2.3 | 0.6 | 0.1 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
10 | 8.4 | 7.1 | 5.0 | 2.5 | 0.6 | 0.2 | 0.0 |
----+-------+-------+-------+-------+-------+--------+-------|
How to use the Tables: a few examples
Example 1:
You drink 1 beer, 24 minutes later you drink a glass of wine, and
61 minutes later you drink a double whisky. What are your ALC and
RAV values after each stage, and what, if any, is your mandatory
SIT?
1 beer = 1 ALC, 1 glass of wine = 1 ALC, double whiskey = 2 ALC's.
You drink the beer. What is your RAV after 24 minutes? In table 2,
look up the ALC value (1) and the SIT value (column A). Your RAV
is 0.8 ALC.
You drink the wine. Your new ALC is now 1 + 0.8 = 1.8 ALC. You SIT
for 61 minutes. Round 1.8 ALC to 2, and 61 minutes puts you in
column C, still in table 2. Your new RAV is 1.0 ALC.
You down your double whiskey, so your new ALC is 1.0 + 2.0 = 3.0
ALC's. Remember to round up to the higher value if on a boundary,
so use 4 ALC's. Look up this value in table 1 and you will see
that you need to SIT 2 hours exactly before you can dive again.
Example 2:
You decide to change your strategy and drink first the double
whiskey, then the glass of wine, then the beer. Redo the
calculations.
Drink whiskey = 2 ALC's, 24 minutes SIT -> RAV = 1.7 ALC's.
Drink wine = 1 ALC, new ALC is 1 + 1.7 = 2.7 ALC's. Use 3 ALC's,
61 minutes SIT -> RAV = 1.5 ALC's.
Drink beer = 1 ALC, new ALC is 1 + 1.5 = 2.5 ALC's.
Looking up in table 1, rounding up to 3, this gives you 1 hour and
10 minutes of mandatory SIT before the next dive.
This example shows an important fact about drinking: drink your
heaviest drinks first, and never reverse profile!
Acute Alcohol Sickness
As alcohol tolerance varies from person to person, it may be
necessary to introduce fudge factors. If you are underweight,
underfed, sick, tired or overdived, add 1/4 ALC to each drink for
each of these factors.
Failing to comply may lead to Acute Alcohol Sickness. There are
two manifestations of Acute Alcohol Sickness, type I and type II,
which are unfortunately not mutually exclusive.
Type I manifests itself as vomiting, type II is commonly known as
the "hang over". If you suffer from either, it is recommended to
have a 12 hour SIT before continuing diving.
Remember that Saturation Drinking may also lead to Acute Alcohol
Sickness, even with the introduction of fudge factors.
For more information on the history of Drinking Tables, and Acute
Alcohol Sickness, read "Deeper into Drinking."
Conclusion
With the NAPI Drinking Tables you can now drink with confidence,
and plan your drinking evening in detail. A quick glimpse at the
tables will give you all the information about your current
alcohol level, and how long you have to wait around before the
next dive!
Remember: Plan your drink, drink your plan!
PS: Good News!
NAPI will shortly introduce the Drinking Computer! This simple
device will show you your current ALC level, your remaining ALC
level before you exceed the limit, and if you exceed the limit,
your time to SIT. You just have to remember to tap the single
button before each drink, pressing it as many times as there are
ALC's in your drink. Be even safer, use the Drinking Computer!
Disclaimer:
As usual, if you believe any of this, please contact NAPI, we have
a course just for you!
Seriously, this is the best rubbish I've written so far, yet it
sounds so good, so believable! Again, the tables are not complete
fiction, but actually calculated.
Cheers
Guido
--
The above was posted in Scuba-L in 1994 and reproduced from da
Feeesh's BHD <tm>
-- Bob.
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