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Subject: [rec.scuba] FAQ: Frequently Asked Questions about Scuba, Monthly Posting
This article was archived around: Sat, 1 Nov 1997 20:11:37 GMT
[dive flag] rec.scuba FAQ [alpha flag]
The FAQ was htmlized on 25 April 1995, by Nick Simicich.
The master for this FAQ is now the HTMLized version. The current
version of the FAQ can be fetched from
http://scifi.squawk.com/scuba.html. If you are reading a text
version of this FAQ, it was prepared by running the FAQ through _lynx
-dump http://scifi.squawk.com/scuba.html_. New email addresses for
scubasearch were added on 25 April 1995.
A question on GPS was added in July, 1995.
In October, an EPIRB question was added, and a new mail-to-news
gateway was posted. A comment about commercial postings ws added as
well. The charters of the subgroups were added in August, 1996.
Please feel free to follow-up with comments or email them to
Welcome to rec.scuba. The newsgroup is for discussion of scuba,
diving, snorkeling, dive travel, and other underwater activities.
Frequent topics are safety, equipment, and certification. We welcome
postings from new folks and old hands.
Where should you post? There have been two subgroups of rec.scuba
formed. If your post has to do with equipment, consider posting in
This group is for discussion of all topics related to scuba
diving equipment: its purchase, its use, and for the sharing of
experiences that others have had with it. Infrequent
advertisements from private individuals are acceptable but
commercial advertising is not.
If your post is more about where to go or the process of getting
there, consider posting in rec.scuba.locations:
The purpose of this group will be to exchange information
(preferably first-hand) about dive sites, dive locations
(including live-aboards), dive operations at these locations,
how to get yourself and your gear there, and where to stay/
eat/play once you do. Commercial advertisements are not
If your post fits into neither of the above two categories, but is
still scuba, snorkeling, or diving related, it should probably go into
Before posting to this group for the first time, please check the FAQ
list (this posting), and also read the newsgroup
news.announce.newusers, which contains many answers to questions about
usenet in general.
Are you a new poster? Or an old poster who frequently gets flamed?
One-to-many communication on mailing lists or newsgroups is a lot
different from the sort of communication you are used to. I strongly
recommend the reading of ftp://ds.internic.net/rfc/rfc1855.txt for
general guidelines about what and how to post.
Table of Contents:
1. Differences between certification agencies. (PADI/NAUI/YMCA/SSI
2. New Diver buying first piece of equipment.
3. Author's personal opinion on mail order.
4. rec.scuba archive sites and how to access them.
5. How to find out about dive destinations.
6. Basic discussion of thermal protection (wetsuit, drysuit,
7. Liquid breathing in the movie Abyss;.
8. Scuba magazines and periodicals.
9. Diving in contact lenses.
10. What about Spare Air or Pony Bottles?
11. What about Casio Dive watches and the depth ratings thereon?
12. I lost my C-card. What do I do?
13. I need a resort referral, cause I want to do my checkout dives
on my upcoming vacation to TinyIsland. Who do I call?
14. I think I got a shoddy course. What can I do?
15. They are cutting off my rec newsfeed. How can I get rec.scuba
16. Is there an FTP site for scuba based software?
17. Are there any good scuba URL's?
18. What about Dive Computers?
19. How about the Chipmunk Method of clearing your regulator?
20. I have a medical condition. Is it safe for me to Scuba Dive?
21. I have a great scuba related GIF/piece of software/sound
sample. What should I do with it?
22. I'm suddenly not getting my rec.scuba postings. What do I do
23. Someone just posted about missing children/a revolutionary 30
day diet plan/a multi-level-marketing scheme/then end of the
world/how to get your green card on rec.scuba. What should I do?
24. Can you use a GPS when diving?
25. Can you use an EPIRB while diving?
26. Some comments on commercial postings in rec.scuba and scuba-l.
Scuba Diving is a dangerous sport which can only be performed in
relative safety if you (a) get training (b) pay attention to that
training and apply it (c) recognize that no matter who you are and how
trained you are, there are dives which are beyond your personal
ability, dives which cannot be safely done with your equipment, and
dives that are beyond your training.
Finally, some dives are just plain more dangerous. Your certification
course should have trained you to recognize your limitations, or,
conversely, to recognize the sorts of diving you were trained to do.
Various people who post to rec.scuba discuss advanced diving. This
stuff is just a discussion. It is not meant to be a replacement for a
certification course with an instructor, and it is not meant to be an
encouragement to you to go out and engage in similar diving without
evaluating your personal skills, and/or getting the appropriate
training and equipment, as required. Specifically, Cave or Wreck or
Deep diving requires advanced equipment, training, and a careful self
Finally, it should be obvious that not everyone who posts their
opinions to the net is or can be (a) an expert or (b) correct. It is
likely that your instructor, for example, would disagree with a number
of the points of view expressed herein, and would probably disagree
with part of this FAQ.
The fact that someone who identifies themselves as an instructor posts
to rec.scuba does not create an instructional situation.
Frequently Asked Questions:
I'm planning on getting certified. I've been to several shops, and they all
offer different certifications. I've heard of PADI, NAUI, YMCA, NASDS and
SSI. Which one should I go with?
This question has frequently come up in rec.scuba. One of the
discussion threads has been summarized as whosbest.txt in the
rec.scuba archives at ames. See the explanation of Peter Yee's
archive, below, for how to access the ames archives. The short, widely
agreed answer, is that agencies all must follow a minimum standard set
by an industry organization, so they differ less than you might
expect. However, instructors differ a lot, and you should try to talk
to the instructor you will be taking the course from and determine
exactly what will be offered, and how you feel about them. Finally,
some instructors add significantly to the standard course (and may
also charge more). You should ask exactly what you are going to get
for your course fees, what else you will have to buy, and where you
have to buy it.
I'm new to diving, and I want to buy some equipment. Which piece of equipment
should be the first?
There are two schools of thought on this. One is that you should
consider only purchasing your personal gear until you are sure what
type of diving you like. This school believes you should buy only
mask, fins, and snorkel, for fit and sanitary reasons. The other
school of thought is that the rental gear you can rent, especially in
tropical locations, is second rate and poorly maintained, and that
gear you purchase will be better and more reliable. Typically, people
agree that you should not buy a tank until you believe that you will
be doing a significant amount of local diving.
Where are good sources for mail order equipment? All of the local shops seem
to be very expensive.
The purpose of a FAQ is to answer commonly asked questions which have
answers that can be agreed to by the majority of the group. There are
many conflicting opinions on mail order that have little to do with
scuba, and, after long consideration, I felt that it was impossible to
write a mail order question answer that was informative, covered all
views, and which generated more light than heat. I suggest a
Subject: mail order
before bringing it up again.
It is my personal opinion that if you are asking this question in this
group that there is a very good chance that you do *not* have enough
knowledge or skill to safely purchase either life support equipment or
equipment ancillary to that, and should reconsider doing so.
Are there any archive sites for rec.scuba? If so, how do I access the
The Peter Yee Archives.
There are two rec.scuba archives. The first, and oldest, is maintained
by Peter Yee. Peter has collected travelogues, equipment reviews, and
so forth into pre-organized files. In Peter's own words:
You can also use the SCUBA archives on ames.arc.nasa.gov. Send
mail to email@example.com (or ames!archive-server)
and use a subject with a line like "send scuba index". This
will get you an index of articles in the archive. They are
sorted by subject and you will that you get pretty much what you
ask for. To get Florida info, try sending a subject of "send
scuba florida.txt keys.txt".
Advantages to Peter's archives are that they are organized by subject,
allow instant access if you have FTP, and are actually about the
subject in question rather than just randomly containing that word or
phrase. Follow this to the ames archive.
The second archive is maintained by (me) Nick Simicich. This is sort
of a minimalist archive. There are over a years worth of articles in
the backlog, and you can run an "egrep" against them and the responses
will be organized and sent back to you. To use the archive, mail to
firstname.lastname@example.org (if that bounces - a correctly operating
scubasearch might take hours) email@example.com.
You can also run a scubasearch through the web if you have a form
capable browser. To run a scubasearch through the web, click here,
which will lead you to
If submitting your search by email, place the search pattern you want
in your Subject: line. The search is CaSe InDePeNdEnT. Up to 10,000
result lines will be sent to you if you put in a general enough search
pattern. As an example, to find articles which contain the string
"dive watch", "diving watch" or close approximations, send mail to
scubasearch with "Subject: div.*watc". "div.*wat" would not be good
because that would get you "dive...water". Another bad search pattern
is "cuba" because that will select every article, because cuba is part
of scuba. Try "\<cuba\>" instead. Multiple level searches: Supposing
you want to find a posting that mentions accidents in the Cayman
islands. You could search for "accident.*Cayman|cayman.*accident", and
that would tend to find some of them, but it wouldn't find postings
where caymans was mentioned in the subject line (for example) and
"accident" was mentioned somewhere in the body. To get around this,
I've added a syntax that the shell script will use to run multiple
grep passes. You just separate the arguments to the successive grep
passes with an &. For our example above, you could code "Subject:
cayman & accident". The shell script will run grep against all of the
files with the argument "cayman" as he search string, and then run
grep again with the search string "accident" against the files that
result from the first pass. You can stack these to an arbitrary depth.
You can also get as complex as you want using this feature. For
example, you might want to do a search for articles that I didn't
write with cayman in the subject. This pattern might do it:
Subject: ^Subject:.*cayman & -v ^From:.*njs
-v can be specified on a second or subsequent grep pattern (after the
&, as shown above) and eliminates all articles that contain the grep
target. This is not a hook for general grep options. This is a special
option that changes the action of the shell script.
You can limit your searching to a particular date range by specifying
a line as follows:
Searchdates: [fromdate] [;todate]
The format of the date is pretty liberal, and can include patterns
such as "01 Jan 91" as well as "1 year ago". You can leave out the
todate, or leave out the fromdate just by starting with a semicolon.
You can get further information about egrep patterns by sending mail
to scubasearch with "Subject: help". There are more detailed
instructions regarding the date and the inverse searching in the help
file, as well.
You can get a copy of this FAQ by sending mail to scubasearch with
"Subject: FAQ". You can do a search for someone else by naming them in
a reply-to line, either in your mail header or the message body.
Advantages are that every posting is there. Disadvantages are that you
will get random stuff which happens to mention your search string if
it is not specific enough, and you might get tons of stuff you don't
want. If you do make a successful scubasearch, consider editing the
result and mailing it to Peter Yee for inclusion into the organized
rec.scuba archives so that the next person has instant access to the
Note that due to a problem on the scifi system, the entire old article
database was wiped out on 8/21/94. The accumulation will start again.
Unforunately, it was just too big to back up with my limited
What can anyone tell me about diving in [Florida, Cozumel, Belize, Bonaire,
Great Barrier Reef, etc.]?
Seriously consider doing a scubasearch or looking in the
archives at ames before asking your question. If there hasn't been any
conversation on your destination recently, then by all means ask.
I'm thinking about buying a [wetsuit/drysuit/diveskin/Darlexx skin].
What are the differences between them, and what are they good for?
Diveskins are typically made of Lycra or some other stretchy fabric.
The warmth supplied is minimal. Typically, they are used to prevent
stings from jellyfish, and to protect from accidental coral contact.
Sport divers tend to wear skins in water warmer than 80F degrees, or
under wetsuits, so that the wetsuit will slide on easier.
Next up in warmth is the Darlexx suit. This is a suit that is similar
to a diveskin, but which is made out of a fabric that slows water
flow. There have been reported problems with the Darlexx fabric
"delaminating" or coming apart. An alternative is made by Aeroskin,
and uses polypropylene and lycra. Depending on how warm blooded you
are, you might be able to wear Darlexx comfortably down to 72F. A
Darlexx suit is a wetsuit. It does not fit like a diveskin, and is not
really a substitute for a skin.
Wet suits are made of neoprene rubber. The suits serve two purposes:
They reduce water circulation over your skin, and the air impregnated
neoprene insulates you from the cold water. At the worst, a poorly
fitting wetsuit can ruin your dive by letting you get so cold that you
get hypothermic, or by being so tight that it cuts off your
circulation. If you are not well fitted by stock wet suits, you can
have one custom made. Custom made wetsuits are not that much more
expensive than stock ones, and fit much better. Wet suits come in
several thicknesses and styles. People wear different styles of wet
suits between 32F-85F. Most people find that temperatures below 45-50F
are not comfortable for longer than a few minutes in a wetsuit.
Dry suits are used by prople between 70F-28F. (For extended commercial
operations at near freezing temperatures, heated water is pumped
through a special suit or underwear set.) (Temperatures below 40
require special environmental protection for regulators, controlled
use of inflators, and (hopefully) redundant breathing systems.) You
should consider getting special training before you wear a drysuit.
Even fitting the drysuit is not quite as straightforward as fitting a
wetsuit. A drysuit is useful at a wide range of temperatures because
you can vary the amount of warmth by wearing different underwear with
The following discussion of drysuits is by firstname.lastname@example.org:
What are the different types of drysuits available and what are the pros
and cons of each type of suit?
Drysuits fall into 4 main categories: foam neoprene suits, nylon or
tri-laminate shell suits, vulcanized rubber suits, and crushed
Foam Neoprene Suits:
These suits are very similar to wetsuits in they are made out of
neoprene with the seams sealed. Even flooded, they will retain much of
their insulating ability and buoyancy. At shallow depths, they are
probably the warmest suits and will require the least amount of
undergarment thermal protection. However, like wetsuits, at depth, the
neoprene is compressed causing a reduction in both thermal protection
as well as buoyancy. Also, they take a long time to dry, and can be
very difficult to repair. Like neoprene wet suits, foam neoprene dry
suits have a useful life of somewhere around 300 dives before the suit
no longer retains sufficient thermal protection.
Nylon or Tri-laminate (Shell) Suits:
Shell suits are made out of various types of nylon. There is a wide
range in the durability and resistance to abrasions of these suits.
The advantages of these suits are that they are very light, easy to
pack, dry very quickly, and are easy to don. They do not stretch so
they must be large and baggy enough to allow freedom of movement. This
can make them higher drag while swimming. They provide no thermal
protection themselves, so appropriate undergarments must be worn. They
are easy to repair in most cases.
Vulcanized Rubber Suits:
These suits have many of the same advantages and disadvantages as the
nylon suits. They are relatively easy to don, they dry quickly, and
repairs are easy. Depending on the thickness of the rubber will
determine how durable the suits are and how resistant to abrasions.
The most durables will be very expensive and the less expensive suits
tend to need repairs often. The drag with vulcanized rubber suits
tends to be high. These suits are often best for diving in
contaminated water (with additional equipment and training of course).
Crushed Neoprene Suits:
These suits are neoprene suits which have been compressed. This means
the suits themselves do not compress at depth so they do not lose
buoyancy or insulation at various depths. The material is extremely
durable and is very resistant to abrasions. The suits are somewhat
heavier than nylon suits and take longer to dry (about 24 hours).
Repairs can be more time-consuming because you must wait for the suit
to be completely dry before doing the repair. The suits are very
flexible, so they are easy to don and are meant to be form-fitting
which reduces drag while swimming. They provide some thermal
protection so you can generally wear less undergarments than with a
shell or vulcanized suit. These suits tend to be the more expensive
types of suits along with the heavy duty vulcanized rubber suits.
Also, as of this year, crushed neoprene suits are available in women's
What type of options are available with drysuits and what are the pros and
cons of each?
There are a number of other items to consider when purchasing a
drysuit beyond the material of the suit itself.
Boots: Most drysuits today come with attached boots. This avoids the
problem of additional seals at the ankles which also make your feet
colder and another place to leak. Some suits have latex or other
sock-like boots. With these drysuits, you wear wetsuit boots over for
abrasion protection and additional thermal protection. Pros are you
can generally wear the same size fins, if your boots wear out, wetsuit
boots are much cheaper and easy to replace. Cons are they can be less
warm than attached boots worn with thermal undergarments.
Wrist and neck seals: Seals primarily are either latex or neoprene.
Latex is more flexible, is easy to don, but requires more care. Latex
seals are less durable and need to be replaced at least every 2 years.
However, latex seals are easy to repair and relatively easy to
replace. Neoprene seals are more rugged, but most people find them
harder to don and more uncomfortable to wear. Neoprene seals also tend
to leak more than latex seals, but they are warmer than latex seals.
Other items to consider: Suspenders will be very useful to keep the
crotch of the suit from sagging. They will be helpful while swimming
or walking out of the water and are especially useful when you remove
the top part of your dry suit. Since one of the most expensive parts
of a suit to repair can be the waterproof zipper, a protection zipper
is very useful. In the case of latex seals, a warm collar is a nice
option as is an attached hood.
I just saw a really great movie called the Abyss.
In it, they had a rat breathing liquid. Is that really possible? Is
there equipment like that for humans?
Yes, it is really possible. The rat was breathing liquid in the scene
you saw in the movie. No, it is not done with people (except with
premature babies to replace missing surfactants - this has been
reported on _Hard Copy_ a US TV tabloid news show, complete with
pictures of the procedures and one of the surviving children). A
widely cited study involved a single adult subject who had one lung
filled with the liquid, but who had problems with pneumonia
afterwards. It is considered highly risky. To pull an old thread on
this from rec.scuba, do a scubasearch with the subject:
The liquid is a chloroflourocarbon, like freon, but with a higher
I want to learn more about diving, and read a lot of diving magazines.
My local newsstand only carries Skin Diver Magazine, which I hear a
lot of derogatory comments about on the net. What other
Magazines/periodicals are there, how do I subscribe, and what is the
orientation of these magazines?
There are many, many magazines and journals. I've created a file
called scubamag.txt, which I have placed in the archive at
ames. This file, too long to place here, reviews many of the
magazines which are around. At this point, many of the comments in
this file are obsolete.
Can I dive in contact lenses (contacts)? Is it safe? Will I go blind?
The safety of contacts revolves around several issues:
Will nitrogen absorption affect the contacts?
It is possible that non-gas-permeable contacts will get bubbles
under them. For this reason, if you do wear contacts, they
should be gas permeable or soft, or they should have holes
drilled in them.
What is the likelihood of losing a contact under water?
If you get water in your mask, and you open your eyes, you
might lose a contact. It might stay in your mask, in which case
you can possibly recover it. If you will be dangerous to
yourself without contacts, (not able to see well enough to find
the boat, and not used to dealing with things by sound) then
this could be serious. You also have to consider the
possibility that your mask will come off underwater, and that
you will have to open your eyes to find it and replace it, and
that your contacts might come off during this process. Losing
contacts in the water has happened to a number of people.
What about the possibility of infection?
You are always at increased risk of eye infection when you wear
contacts. There is some possibility that there are bacteria in
the water that will increase the risk of eye infection. Quick
treatment in the case of contact related infection is
important, and you are not likely to get that treatment on, for
example, a liveaboard.
At least one study has indicated that there is an increased
possibility of Acanthamoeba infection when swimming with
contact lenses. Other practitioners, who do prescribe soft
contacts for swimmers, claim that there is no proof that the
contacts were the proximate cause of the infections, but give
no arguments as to why they feel that there is no correlation.
Are there any special considerations regarding soft contact lenses?
Yes. Dr. Soni, Associate professor of Optometry at Indiana
University has participated in a study which showed that 100%
of soft contact lenses used in pool swimming were contaminated,
when cultured. Normally, soft contact lenses are made up of a
certain percentage of water. They absorb this water from your
tears, and the amount of water they absorb is at least
partially dependent on the salt content of your tears. When you
swim with contact lenses, and you open your eyes, the lens
readjust to the water content of the liquid you are swimming
in. This causes them to stick to your corneas. It is claimed
that it takes 1/2 hour after swimming for the lenses to
equilibriate to tears, and that removal of the lenses before
they equilibriate can damage the cornea, creating a "clear
passage into the cornea for the bacteria from the contaminated
lenses, which will cause infection." Even practitioners who
strongly believe in swimming with contact lenses feel that
disclaimers should be given when prescribing the lenses for
this purpose. The lenses are not approved by the US FDA for
swimming, but this may be just because no tests have been done.
Some of the above information was extracted from an article
from Eyecare Business magazine, the June '91 issue.
Now, many people wear contacts in the ocean without problems, whereas
others prefer prescription masks. If you have simple myopia, there are
several brands of masks with snap in lenses that can be made up
quickly in your dive shop. If you have a more complex prescription,
there are optometrists who can glue lenses into your mask. Many people
seem to really like these.
Whatever you do, please avoid asking this question in rec.scuba. It is
a very frequently asked question. Do a scubasearch on "contacts" or
"prescription", and you will get many thousands of lines of opinion.
People should follow up to this question by email if it is asked again
[IMHO], unless they have new study information or something to quote
that is substantive. (If it is substantive enough, I'll put it in as
part of the FAQ answer.)
I'm thinking of getting a redundant breathing system,
in case I have a hose failure or run out of air, and can't find my
buddy. I've heard about something called "Spare Air", and also "Pony
Bottles". Should I buy one? Or is there something better?
First off, carrying a redundant breathing system is a good idea. There
are a couple of important questions.
1. What are the types of redundant systems, and how much do they
2. How much air do you need to be safe in case of a problem?
3. How likely are you to carry your redundant system with you
when you dive and vacation?
Types of redundant systems.
What sorts of redundant systems are there? First, by "redundant
system" I'm referring to a system that will continue to work no matter
how catastrophic the failure of your main system. Thus, I won't
consider a Y valve a redundant system because of the fact that a burst
disk could rupture or an O-ring could fail and exhaust your entire air
supply, or, that because of an error or a bad gauge, you could exhaust
your entire air supply. The three most frequently used redundant
1. the bailout bottle,
2. the pony bottle and
3. the independent twin tank.
Some British BCs have a small air bottle attached to the BC. With
proper training and practice, it is possible to use this air for
breathing. But since this isn't a straightforward regulator system, we
won't discuss it here either.
The bailout bottle is available in sizes as small as 1.2 cu ft, and as
large as 3 cu ft. The best known brand is "Spare Air". The bottle has
a regulator that must (for older models) be switched on before use.
Bailout bottles can cost between $200-$300. The ones sold at a
discount by mail order houses are typically smaller bottles of older
The pony bottle is a smaller spare tank that is actually a small
standard scuba bottle, and attaches to a standard regulator. Many
people use an inexpensive regulator on their pony bottles. You also
need some sort of mounting system. Pony bottles can cost between
$250-$350 depending on the regulator selected, the size of the pony,
and the care you take while shopping. You can get a 13 cubic foot pony
(in 2000 PSI and 3000 PSI models), a 17 cubic foot pony, a 30 cubic
foot pony, a 40 cubic foot pony, and some other sizes.
The independent twin tank is a second tank which is the same size as
your first tank, and which has its own regulator. Since the two tanks
fit into a single double tank bracket, they may look like a set of
doubles, but, in fact, they are two separate tanks. The independent
twin tank is a good option for certain specialty diving, like wreck
penetrations or extreme deep diving, but I won't discuss it further
here. Costs vary widely depending on how much the mounting costs, the
type of tank, and so forth.
How much air do you need to be safe?
The following chart was produced by Dave Waller, and presents a
picture that I feel is conservative. You should probably assume that,
in an emergency, you will be breathing at one of the higher breathing
rates. It also assumes a 60 fpm ascent rate, which is considered too
fast by many computer models and some training agencies. Therefore,
these numbers should be considered minimums, and any deviation from
these conditions would be likely to cause these numbers to increase.
Total consumption (ft^3) # Total consumption (ft^3)
without 15_ft Safety Stop  # with 15_ft Safety Stop [1,2]
Consumption rate (ft^3/min) # Consumption rate (ft^3/min)
Depth | 0.5 | 1.0 | 1.5 | 2.0 # 0.5 | 1.0 | 1.5 | 2.0
60 | 1.66 | 3.32 | 4.98 | 6.64 # 2.75 | 5.50 | 8.25 | 11.00
80 | 2.33 | 4.66 | 6.99 | 9.32 # 3.42 | 6.84 | 10.27 | 13.69
100 | 3.10 | 6.21 | 9.31 | 12.41 # 4.19 | 8.39 | 12.58 | 16.78
130 | 4.45 | 8.90 | 13.36 | 17.81 # 5.54 | 11.08 | 16.63 | 22.17
150 | 5.48 | 10.95 | 16.43 | 21.91 # 6.57 | 13.13 | 19.70 | 26.27
200 | 8.48 | 16.96 | 25.45 | 33.93 # 9.57 | 19.14 | 28.72 | 38.29
 Total consumption includes 30 seconds at indicated depth, and
a 60_ft/min ascent rate.
 Assuming a 1/2 consumption rate during a 15_ft safety stop
for 3 minutes.
The numbers beyond sport diving depths are here only for reference,
and not to encourage you to dive those depths. Redundant air only
reduces one of the dangers you would face in diving to those depths.
The largest Spare Air holds just under 3 cubic feet. The smallest
available pony bottle holds 13 cubic feet. You can look at the chart,
estimate your surface consumption rate, try to estimate what it would
be in an emergency, and see where you fit in.
It is almost certain that if you were diving deep, you'd want more air
than the chart shows, as you might need to make a longer decompression
While some people have tested bailout bottle ascents from as deep as
100 fsw, it should be emphasized that these tests were not performed
under stressful conditions. Typically, they are already neutrally
buoyant, ready to ascend, and are consuming less air than they would
in an emergency. Referring to the above chart, you can see that this
would be possible for a diver who had a consumption rate of 1/2 cubic
foot per minute, and who left immediately upon switching to their
bailout bottle rather than taking time to get settled.
How likely are you to carry your pony?
People who prefer bailout bottles to pony bottles say that a pony
bottle is too cumbersome to transport and wear and in fact is not
carried, making it a useless boat decoration. Pony bottle proponents
who carry their pony bottles with them when they travel say that they
don't have a problem carrying them, and many wear them all of the time
when they dive. They disagree that it is too hard/painful/time
consuming to dive with a pony bottle.
Opponents of bailout bottles believe that bailout bottles are useless
diver decorations, mainly because the bailout bottles do not contain
enough air for an emergency. They argue that from the time you switch
to the bailout bottle, you have only enough air to ascend directly to
the surface. You have no time to solve problems and little or no air
to make yourself positively buoyant. A final argument is that a
bailout bottle might actually give you a false sense of security, and
make you less safe than you might be without one.
Perhaps the final judgment should be made using the above chart, and
the depth to which you plan to dive. If $$/cubic foot is a
consideration for you, then you would probably prefer a pony bottle to
a bailout bottle. Many people do all of their diving between 15-40
feet, and never dive deeper than 60 feet. These people would probably
find the largest bailout bottle useful. If you go deeper, or if you
might go deeper someday, consider a pony bottle of the appropriate
There have been rare occasions (one reported, at the Hong Kong airport
only) where people have been told that they simply can't bring their
scuba bottles on their flight, valves on or off, and have had to
abandon them at the airport. This would probably equally apply to
bailout bottles and pony bottles. You should plan on draining your
bottles of any type completely before flying to comply with airport
regulations, and you may have to remove the valves to prove to the
airline's satisfaction that the bottles are completely drained. It is
a violation of US FAA regulations to transport a bottle on an airliner
pressurized to more that 41 PSIA. Airlines may have more stringent
My Casio dive watch flooded.
It was rated to 50M and I was only at 15M. What gives?
The Casio dive watches are supposedly rated in static pressure, not
dynamic pressure. The act of swimming, moving your wrist, bumping the
watch, using the controls, etc., causes large amounts of dynamic
pressure, which can flood your watch.
Casio used to rate their watches by activity. 100M watches were rated
for snorkeling, and only 200M watches were rated for scuba diving. 50M
watches were for showering.
Net experience seems to indicate that your 50M watch is quite likely
to flood if you use it for diving, your 100M watch is somewhat likely
to flood, although some people have used 100M watches for diving
successfully, and your 200M watch is probably not going to flood. A
few people have used 50M watches for diving, but pushing the buttons
at depth, accidentally or on purpose, may flood the watch.
Given that a Casio G-Shock is only about $50 at a discount store, and
that a regular 200M Casio is likely to be around $40, many people seem
to think that skimping further than that (since that is about the cost
of a dive) is false economy, since, if your watch was your only timing
device, you'd have to abort if it flooded.
There are people who believe that this means that some watches are
rated in "marketing meters" and others are rated in "real meters".
Regardless of that, 200M Casios seem to work for scuba and others are
If you are interested in information on the Citizen Hyper Aqualand,
and you are not happy with the software you got with your watch, you
might try the following URL:
ftp://ftp.netcom.com/pub/ca/cader/scuba which contains information and
utilities to dump the Citizen Hyper Aqualand.
I've lost my C-card. What do I do?
Um, how long has it been since you have done any diving? And how much
diving did you do when you were current? If it has been a long time,
maybe you should consider taking a new certification course. Your old
certification card may still be good, but equipment changes all of the
time, diving practices and techniques change all of the time, and
unless you've been keeping up, you may find yourself either at a loss,
or not diving as safely as you might without current training.
Now, the first step in replacing your C-card to consult your
instructor, or the dive shop you were taught through. They should have
a copy of your records. If you can't contact them, calling the
certification agency might well be your best bet. Here are some
certification agency numbers.
Scuba Schools International (SSI)
+1 (303) 482-0883
The Italian arm of SSI can be contacted through:
SCUBA SCHOOLS INTERNATIONAL ITALIA
Via Bergami 4
40133 BOLOGNA - ITALY
tel. +39 51 383082 - fax +39 51 383554
National Association of Underwater Instructors (NAUI)
(800) 553-NAUI (USA) or +1 (714) 621-5801
NAUI Canada: Call NAUI in California.
Email: email@example.com or firstname.lastname@example.org
Handicapped Scuba Association (HSA)
+1 (714) 498-6128
Professional Association of Diving Instructors (PADI)
USA (714) 540-7234
National Young Men's Christian Association SCUBA Program (YMCA)
American Nitrox Divers Inc. (ANDI)
International Diving Educators Association (IDEA)
National Association of Scuba Diving Schools (NASDS)
The phone number for NASDS is
800 735-3483 [(800) 735-DIVE]
Professional Diving Instructors Corp. (PDIC)
(717) 342-9434, Fax (516) 546-6010
The address of CMAS is:
Viale Tisiano 74
"Contact by Phone is known to be Erratic"
I'm going to somesmallisland, and I'm looking for a shop that will complete a
referral from (NAUI/PADI/SSI/etc). Can someone suggest one?
It depends. If you're looking for a referral, try talking to your
instructor, or to your dive shop. Alternatively, a dive travel agent
might be able to help you get into a good place, and arrange your
checkout dives for you as well. Finally, do a scubasearch for your
area, and then maybe ask on rec.scuba.
Also, the certification agencies maintain referral lists. See the
answer to question 12, and call them. They may be able to refer you to
an instructor or a facility that can complete your referral.
Um, I got certified, and I'm reading the stuff on rec.scuba, and I think that
I got a shoddy course from my instructor. What should I do?
Call your agency (see agency list above) and get the address to
write to complain to them. The general rule is that they will
investigate (especially if they get several complaints) only based on
complaints in writing, and that they will not contact you to tell you
the results of any action that they take. They will investigate one
complaint, if it is really blatant.
They are cutting off my rec.scuba newsfeed.
What can I do to still get rec.scuba?
There are two ways to get scuba related mail. Both involve the bitnet
listserv system, and both are run from Brown University. The LISTSERV
administrator there is Catherine Yang, but these things are designed
to be administered automatically. The two lists are scuba-d, which
holds the scuba digests that are constructed from the postings to
rec.scuba, and scuba-l which is a completely independent scuba related
discussion list. There are some scuba-d archives available at
You never send subscribe or unsubscribe requests to the address of the
list. In fact, if you do, they will be relayed to all of the people
who get stuff from the list (and probably ignored). To sign onto or
sign off from a listserv list, you send mail to userid LISTSERV. For
example, to sign on to scuba-d so that you still get the rec.scuba
postings, send mail to LISTSERV@BROWNVM.BROWN.EDU, with the text:
SUB scuba-d your name
You must replace the string 'your name' with your own name. To
subscribe to scuba-l, send the same message, but replace scuba-d with
To find out more about how to use the listserv system, send mail to
LISTSERV with a text line that says 'HELP'. For your convenience, the
response to a HELP command is reproduced below.
If you don't have the ability to post news to rec.scuba locally, you
can mail your postings to email@example.com. (This is not
a general mail-to-news gateway, it works only for a few groups in
which I have a personal interest.) This is how someone with e-mail
only access could post to rec.scuba after reading the newsgroup via
the scuba-d mailing list. To post to rec.scuba.equipment, mail your
postings to firstname.lastname@example.org and to post to
rec.scuba.locations, mail your postings to
The process that produces scuba-d purposely tries to delay postings
until it gets a complete thread. In particular, it will use the
References: fields and commonality of Subject: contents to try to
build a time ordered thread. It selects threads to put into a
particular digest by looking at the age of the oldest posting in a
thread. When a thread is selected for output, the entire thread is
output. Thus, postings may not come out in an order that seems
'logical', especially if people follow-up to unrelated postings. There
is a logic to it, however. A side effect of this is that the headers
come out in a different order than the postings do, in any particular
digest. All postings do eventually come out of the other end of the
pipe. Under normal circumstances, as many as four digests may be
posted per day.
Revised LISTSERV version 1.7c -- most commonly used commands
Info <topic|?> Get detailed information files
List <Detail|Short|Global> Get a description of all lists
SUBscribe listname <full_name> Subscribe to a list
SIGNOFF listname Sign off from a list
SIGNOFF * (NETWIDE - from all lists on all servers
REView listname <options> Review a list
STats listname <options> Review list statistics
Query listname Query personal distribution options
SET listname options Set personal distribution options
INDex <filelist_name> Obtain a list of LISTSERV files
GET filename filetype Obtain a file from LISTSERV
REGister full_name|OFF Tell LISTSERV about your name
There are more commands (AFD, FUI, PW, etc). Send an INFO REFCARD
for a complete reference card, or INFO ? for a list of available
Peter DiCamillo / ListMaint <CMSMAINT@BROWNVM>
Is there an FTP site for Scuba based software?
Jonathan: email@example.com says:
I am hosting a diving software archive here at halcyon - if you want
to put me in the FAQ as a site for scuba related software, feel free
to do so. Its small now, but I am building it as I find more stuff. as
of now, it is only PC based stuff, but I am looking for Mac/Unix/Amiga
as well. contact me for more information if you need it.
It can be reached through the web at :
(changed on 18 July 1996:)
Are there any good scuba URLS?
Time for a shameless plug. The author's URL is
http://scifi.squawk.com/njs.html and there are some good links
there. Stop by and light up the world!
Also, the NOAA web site address is:
E-mail contact is firstname.lastname@example.org
Here are more interesting scuba URLs:
* http://darkwing.uoregon.edu/~stimac/scuba.html - a list of
other scuba urls.
* http://search.yahoo.com/. In this case, a search specifically
about scuba related web pages will be done automatically when this
link is selected.
* http://www.his.com/~tom/dc-scuba.html The dc-scuba web site.
* http://www.naui.org/ The NAUI home page.
What about dive computers?
Kevin Grover, grover@CS.UNLV.EDU, tells me:
About the blurb on dive computers. The information is no longer
preliminary. It is now in version 2.0 and is called "Internet Dive
Computer Review" (IDCR for short).
Also, it is a multipart HTML document with a main file of:
If you could update the rec.scuba FAQ it would be great. (BTW the
above document also includes addresses, phone numbers, fax numbers,
email/ftp/www addresses for manufacturers).
(Currently there is no FTP file, I'm working on putting something
I heard someone mention the chewing or chipmunk method of clearing your
I wasn't taught it. What does this refer to?
There are actually several methods of clearing regulators. It almost
seems that regulators want to be clear. The two that most folks are
taught are exhaling and pushing the purge button. You can also seal
around the reg mouthpiece with your lips and either use your tongue as
a piston, or use a chewing motion. As your mouth volume decreases,
water will be forced out through the reg exhaust, and as your mouth
volume increases, air will be drawn in through the demand valve. In
3-5 quick cycles, your reg will be clear.
This is handy if you've exhaled all of the way, and your hands are
full, such as when you are doing a buddy breathing exercise. Try it
sometimes, preferably in shallow water the first time.
I have a medical condition. Is it safe for me to scuba dive?
Scuba diving is a physically demanding sport, which requires a healthy
heart, well able to tolerate exercise, and healthy lungs.
Additionally, any illness which might incapacitate you, such as with a
siezure, or with unconsciousness, such as uncontrolled fainting. There
are many medical conditions which are considered disqualifying for
scuba diving. The Diver's Alert Network (phone +1.919.684.2948) will
provide over-the-phone advice about medicine, medications, diving, and
their interaction, as well as assisting you in finding the appropriate
chamber or a local doctor who is familiar with diving medicine and so
forth, and is a worthwhile organization to join.
Some medical conditions which are generally considered disqualifying
(although there are exceptions for well controlled conditions, in some
cases, consult your doctor) are asthma, diabetes, epilepsy or any
other siezure disorder, history of spontaneous (or, from some sources,
any) pneumothorax, emphesema, heart illness which inhibits your
ability to exercise to a certain level, and others.
There is some experimental evidence that diving while pregnant could
be dangerous for the fetus, so it is contraindicated. This is a
compressed air issue, so shallow, reasonable snorkeling should be
fine, if your doctor says you can tolerate exercise and swimming.
I have a great scuba related GIF/piece of software/sound sample. What
should I do with it?
Please bear with me for a second. By convention, the net is divided
into areas. There is an area for written discussion, an area for
posting gifs, an area for posting binaries, and an area for posting
sound samples. The total volume of postings in the net is very high.
It is so high that many sites are picking and choosing the posting
areas (rec, alt.binaries, etc.) that they want very carefully. One
area that many sites have cut is binary postings. Many news
administrators consider binary postings to be marginally useful, in
comparison to their size. So they don't carry them.
I suspect that many news administrators also consider rec.scuba to be
of marginal utility. If rec.scuba becomes loaded with binaries, it
will be considered a binary group, and will be dropped by those sites.
Finally, many folks pay by the byte for their connections. If they get
rec.scuba, they have signed up for discussion, not for binaries.
Please respect their wishes.
If you have a binary you wish to make available, contact Peter Yee
or Jonathan <email@example.com> and let them know. If you want to post
it, post it to the right alt.sources or alt.binaries group, and post a
reference to it here in rec.scuba.
My rec.scuba stopped!
For some reason, I'm not getting rec.scuba/scuba-l/scuba-d. What
should I do?
Well, there are many things you can do. You can contact your news
administrator, who should know what to do about contacting your
upstream sites. If you are on a pay service, contact your help desk.
What you should *not* do is cluelessly post a test to rec.scuba. This
is incredibly rude, as well as useless. What will probably happen with
your test is that whatever is holding up your newsfeed will hold up
your test posting, and no one will see it until the logjam is broken.
Then it will be distributed, at just about the same time you start
seeing postings again. Alternatively, it will be distributed
immediately, because the blockage is one way, and people will respond
to it, but it will all be useless, because you won't have seen the
responses. You will be wasting your time, and everyone else's, as well
as network bandwidth.
Occasionally, a news administrator will have a specific problem with
propagation of rec.scuba, and will have to post a test. Those postings
are few and far between. If they ask for a response, respond via
email. Generally, news administrators can use a group such as
misc.test for testing.
The above also applies to scuba-l. It is clueless, rude, and a waste
of time for the average individual user to post tests in public
newsgroups or mailing lists, and it is equally clueless, although less
rude, to respond to them in public newsgroups. Contact the your news
administrator if you think you are having trouble with news. Contact
your postmaster if you think you are having trouble with email.
Contact the mailing list maintainer if you think you are having
trouble with a mailing list (typically at the listname-request
address, or, for scuba-l and scuba-d, at firstname.lastname@example.org,
for automated help).
It is a good idea to restrain yourself and not respond to these
postings in public. In fact, it is a good idea not to respond at all.
There are automatic responders listening to misc.test, just waiting to
eagerly and automatically respond to your posting.
Someone just posted about...
missing children/a revolutionary 30 day diet plan/a
multi-level-marketing scheme/then end of the world/how to get your
green card on rec.scuba. What should I do?
This is called "spamming". More and more frequently, these days,
people are putting this sort of stuff on the net in the hopes of
making some money. Generally, the best thing to do is ignore it.
However, if you feel that you must take some action, then mail to
their postmaster. Include the entire message, including all of the
headers, such as path, etc., to allow the postmaster to more
accurately determine if it originated at their site, or was forged. Do
be careful in your wording, however: Some of these postings are forged
in the hope of causing a site to be flooded with hate mail.
For my site, scifi.squawk.com, my postmaster address would be
email@example.com (me) or firstname.lastname@example.org.
Can you use a GPS while diving?
GPS stands for Global Positioning System. It is a system that was
launched by the US Government to use in military applications.
Additionally, For more information, see
http://www.utexas.edu/depts/grg/gcraft/notes/gps/gps.html, or do a
yahoo search on the word GPS.
An ordinary hand held GPS, with a directly attached antenna, will not
work under water. The frequencies and signal strength of GPS are such
that they will not penetrate more than a very thin layer of water.
GPS accuracy is usually only a couple of hundred feet. It is affected
by a number of factors including intentional fuzzing of the signals
used by civilian units called Selective Availability or SA (since
precise positioning is considered to be information that has military
value), variations in the speed of light as signals pass through the
atmosphere, and other similar sorts of things.
There are a couple of useful things that you can do with GPS regarding
1. You can use it to position the boat near the dive site. You may
not be able to actually drop an anchor after doing GPS
2. You can use it to log your dives if it will hold enough waypoints
and has some capability to enter alphabetics.
3. You can play with it during the boring trip to the dive site.
4. There is a military GPS unit that has a floating antenna. It is
designed to be used for combat swims.
5. You could keep it in a waterproof case and use it and your hand
held marine radio to report your position to the Coast Guard after
you drift away from your boat.
Can you use an EPIRB while diving?
An EPIRB is an emergency radio beacon used in lifeboats and by downed
airplanes to attract attention. They are used by divers who are
worried that they might lose their boat because of current, or because
of drift diving. Commercial divers who work in high current use them.
Marine EPIRBs are designed to be used on lifeboats. They must resist
immersion, and splashes, and must work when wet. Generally, they do
not have to resist deep immersion.
Transmission of an EPIRB signal is equivalent to the transmission of
an SOS. The EPIRB signal will not be received if the antenna is
immersed. If the Minnow had an EPIRB, Gilligan would have been
rescued. :-) (US TV Joke.)
The most apparently waterproof is the Litton Micro B. It fits into a
BC pocket with the antenna folded over, and is hermetically sealed.
The batteries must be replaced by the factory, after seven years. It
is rated to 30 feet by the factory, but like the 50 meter watches,
mine still works properly after deep immersion, and uses a magnetic
through-the-case switch, so keep it away from magnets. It is
positively buoyant (it floats).
Every year, some divers are lost during lobster season here in Palm
Beach county. They get blown away from their boats by current, or they
separate from the other groups in their drift and the boats lose sight
of their flag, and they don't get picked up, sometimes for days, if at
all. A working EPIRB would get the Coast Guard on the scene, even if
they couldn't be reported.
It should be pointed out that your EPIRB requires an FCC license in
the US and the license you already might own may have to be amended to
include the EPIRB if you don't already have one. A single ground
station and a satellite can triangulate your transmission to within 10
If you are not in the US, you should check with your local coastal
marine authorities to see what licensing is required and if the local
authorities will respond to the signal.
Some comments on commercial postings in rec.scuba and scuba-l.
There has long been great controversy over commercial postings on
Usenet and in the scuba-l mailing list. Commercial postings clearly
generate more heat than light. Some people clearly appreciate
commercial postings, while other folks are completely alieniated by
them. Since the purpose of a FAQ is to reduce the heat in the
newsgroup, I feel that I should present a compromise that I feel that
most people are willing to live with, without generating heat.
Generally, I think that the following is considered reasonable:
1. Set up a world wide web site. Since people visit your world wide
web site because they want to, you can advertise as much as you
want, on _your web site._
2. Make postings that are relevant and valuable in the scuba-l
mailing list or rec.scuba.
3. Contribute generally to the discussion, not only to items which
relate to your line of business.
4. Allocate one line in your .signature file to announce what you do
and your web site's url. Appropriate examples would be:
+ See our dive travel specials at http://www.divetravel.com
+ http://www.tankblast.com - Special prices on tank
+ Special deals on fin straps at
5. Hold your whole .signature to four 80 column lines, or less. You
will see people with huge block signatures from time to time. Be a
good net citizen and avoid that practice. Avoid framing your
signature, ascii graphics, and other irritating practices. Your
goal is to get prople to visit your site and see your advertising
and you will do that by being as unirritating as possible while
impressing people with your general knowledge of scuba.
6. If someone asks a question about your product, consider answering
them in e-mail. If you feel that you should answer in the open,
post a a short factual answer and a reference to a URL rather than
a sales pitch.
If people believe that you are making irrelevant postings just to push
your URL into their line of sight, they will be just as irritated at
you as if you posted outright advertising.
On the other hand, if you avoid irritating people, they will want to
do business with you. That is what you want, and I believe that the
redustion in the total heat will be what the folks in rec.scuba and
Finally, consider posting your announcement to the scuba-commerce
mailing list. You'll find an audience that has signed up to see your
commercial announcement, on a list where chit-chat is frowned upon.
See the scuba commerce web page for instructions on how to
subscribe, or mail to email@example.com to
subscribe and for posting instructions. This is a closed list. You
must be subscribed before you can post.
[back]Back to squawk.com home page
That which does not kill us, makes us stronger.
That which does kill us makes us smell stronger, after a few days, anyway.
Nick Simicich mailto:firstname.lastname@example.org or (last choice) mailto:email@example.com
http://scifi.squawk.com/njs.html -- Stop by and Light Up The World!