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Archive-name: scuba-faq
[dive flag] rec.scuba FAQ [alpha flag]
The FAQ was htmlized on 25 April 1995, by [1]Nick Simicich.
The master for this FAQ is now the HTMLized version. The current
version of the FAQ can be fetched from
[2]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
[3]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
njs@scifi.squawk.com.
_________________________________________________________________
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
rec.scuba.equipment:
CHARTER: rec.scuba.equipment
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:
CHARTER: 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
appropriate.
If your post fits into neither of the above two categories, but is
still scuba, snorkeling, or diving related, it should probably go into
rec.scuba.
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 [4]ftp://ds.internic.net/rfc/rfc1855.txt for
general guidelines about what and how to post.
_________________________________________________________________
Table of Contents:
1. [5]Differences between certification agencies. (PADI/NAUI/YMCA/SSI
etc.)
2. [6]New Diver buying first piece of equipment.
3. [7]Author's personal opinion on mail order.
4. [8]rec.scuba archive sites and how to access them.
5. [9]How to find out about dive destinations.
6. [10]Basic discussion of thermal protection (wetsuit, drysuit,
darlexx).
7. [11]Liquid breathing in the movie Abyss;.
8. [12]Scuba magazines and periodicals.
9. [13]Diving in contact lenses.
10. [14]What about Spare Air or Pony Bottles?
11. [15]What about Casio Dive watches and the depth ratings thereon?
12. [16]I lost my C-card. What do I do?
13. [17]I need a resort referral, cause I want to do my checkout dives
on my upcoming vacation to TinyIsland. Who do I call?
14. [18]I think I got a shoddy course. What can I do?
15. [19]They are cutting off my rec newsfeed. How can I get rec.scuba
by email?
16. [20]Is there an FTP site for scuba based software?
17. [21]Are there any good scuba URL's?
18. [22]What about Dive Computers?
19. [23]How about the Chipmunk Method of clearing your regulator?
20. [24]I have a medical condition. Is it safe for me to Scuba Dive?
21. [25]I have a great scuba related GIF/piece of software/sound
sample. What should I do with it?
22. [26]I'm suddenly not getting my rec.scuba postings. What do I do
about testing?
23. [27]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. [28]Can you use a GPS when diving?
25. [29]Can you use an EPIRB while diving?
26. [30]Some comments on commercial postings in rec.scuba and scuba-l.
General Disclaimer:
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
examination.
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
[31]scubasearch with:
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
rec.scuba archives?
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 archive-server@ames.arc.nasa.gov (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".
-Peter Yee
yee@ames.arc.nasa.gov
ames!yee
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 [32]this to the ames archive.
Scubasearch
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
scubasearch@scifi.squawk.com (if that bounces - a correctly operating
scubasearch might take hours) scubasearch@scifi.emi.net.
You can also run a scubasearch through the web if you have a form
capable browser. To run a scubasearch through the web, click [33]here,
which will lead you to
http://scifi.squawk.com/cgi-bin/scubasearch-cgi.
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 "\" 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
information.
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
resources.
_________________________________________________________________
What can anyone tell me about diving in [Florida, Cozumel, Belize, Bonaire,
Great Barrier Reef, etc.]?
Seriously consider doing a [34]scubasearch or looking in [35]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 suit.
The following discussion of drysuits is by mdm@yeehah.merk.com:
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
neoprene.
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
sizes.
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 [36]scubasearch with the subject:
^subject:.*liquid scuba
The liquid is a chloroflourocarbon, like freon, but with a higher
boiling point.
_________________________________________________________________
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 [37]scubamag.txt, which I have placed in the archive at
[38]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 [39]types of redundant systems, and how much do they
cost?
2. [40]How much air do you need to be safe in case of a problem?
3. [41]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
systems are
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
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