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[rec.scuba] FAQ: Frequently Asked Questions about Scuba, Monthly Posting

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                    [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] If you are reading a text
   version of this FAQ, it was prepared by running the FAQ through _lynx
   -dump 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
   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:
   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
   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 [4] for
   general guidelines about what and how to post.
   Table of Contents:
    1. [5]Differences between certification agencies. (PADI/NAUI/YMCA/SSI
    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,
    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
   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  Send
      mail to (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

   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.
   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 (if that bounces - a correctly operating
   scubasearch might take hours)
   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
   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
   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 [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
    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 [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
    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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