From artg@nospameclipse.net Thu Apr 15 15:09:40 PDT 1999
From: please@dont.spam.me (Art Greenberg)
Newsgroups: rec.scuba.equipment
Subject: Re: DRYSUIT - What's your opinion
Date: 15 Apr 1999 17:54:01 GMT

There are at least five materials from which drysuits are made; the more common
types found in sport diving are foam neoprene, compressed or crushed neoprene,
trilaminate, nylon and vulcanized rubber.

Foam neoprene is the same stuff wetsuits are made of. Its primary advantage is
low cost. Its also fairly easy to repair in the field. The tradeoffs include
loss of insulation and buoyancy with increasing depth as the neoprene
compresses. This type are best suited for moderately cold water (I would say
above about 15C) as its difficult to layer thick insulation underneath the
suit.

Compressed or crushed neoprene does not change its (minimal) insulating
properties or buoyancy with depth. Since it has very little inherent
insulation, appropriate undergarments must be worn.  These suits tend to be
quite heavy, especially when wet, and take a long time to dry. They are
generally able to take considerable abuse. The material does have a little
"give", so a good custom fit is possible. Field repairs are moderately
difficult. These suits tend to be the most expensive.

Trilaminate is made by layering nylon on both sides of a thin sheet of rubber.
Depending upon the nylon used, this can be very puncture and tear resistant.
These suits are much lighter than neoprene, but aren't able to stretch at all,
so they tend to be cut a little large to make donning easy. They dry very
quickly. They have even less inherent insulation than compressed neoprene, and
so require an appropriate insulating undergarment. Minor punctures and small
tears are easily repaired in the field. The cost of trilaminate suits typically
falls between the compressed/crushed neoprene and foam neoprene.

Nylon suits can be had fairly inexpensively. They are made by coating a nylon
sheet with a waterproof chemical such as polyurethane. These suits are not as
durable as the others, but are very light and dry very quickly. Needs to be cut
large as the material does not stretch. There is no change in insulating
properties (essentially none) or buoyancy with depth. Minor punctures and small
tears are easily repaired in the field.

Vulcanized rubber is very tough, and is easily repaired in the field. They are
heavy and dry faster than all of the others. There is no change in insulating
properties (which are minimal) or buoyancy with depth. Cost about the same
as trilaminate.

In addition to the body materials, there is a choice of seal material, either
foam neoprene or latex. Neoprene seals have some inherent insulating properties
and so are warmer than latex, but they do not conform to the wrist or neck as
well as latex does. Some people have prominent arteries and/or tendons that
render neoprene seals undesireable. Neoprene seals also stretch with time,
while latex does not until it gets old and starts to "check", at which time it
becomes wise to replace the seal. Latex seals, especially if they're made of
thin material to conform well, are more fragile than neoprene seals. Some
manufacturers offer the option of having neoprene on top of nylon, which makes
for a very durable and very dry combination.  Typically, foam neoprene suits
are offered only with neoprene seals, and vulcanized rubber and nylon suits
only with latex seals. Compressed/crushed neoprene and trilaminate suits can be
had with either or both.

Then there's the choice of zipper style, across and behind the shoulders,
across the front of the torso horizontally, or across the front of the torso
diagonally. (There is one foam neoprene suit, the Poseidon Unisuit, with a
zipper that runs vertically up the front and around the back of the neck like
an upside down "J" - I don't know if that suit is still made). None are truly
"self donning", but those with the zipper in front are closest to that, and
require a little more material than the back-zip styles to allow easy donning.
Such suits usually have some means of gathering the extra material after
closing the zipper so it doesn't contribute to drag in the water.

There is also a choice of boots. So-called "hard" boots resemble snow boots,
and can be good for shore diving involving rocky entries. DUI makes a boot with
a hard sole and foam neoprene upper, and more recently, the "rock boot" in
which the boot attached to the suit is just a soft neoprene bootie over which a
shoe not unlike a hiking boot is donned and laced.

It is important to get a proper undergarment for those suits that require one.
Inside the suit, the humidity will be high, and in cold water that moisture
will condense on the inside surface of the suit. The undergarment should not
conduct that moisture to your skin. Stay away from cotton, as cotton will soak
through and once wet, it will stay wet, and loose whatever insulating value it
had.  IMO the undergarments sold specifically for the purpose are worth their
hideous cost.

I have dived a trilaminate suit (Andy's Undies) for several years now here in
New Jersey and in North Carolina. It adapts well to water temperatures from
about 5C to 20C by changing the undergarment. I just purchased a crushed
neoprene suit (DUI), and have yet to dive with it.  The Andy's suit is very
basic off-the-rack, back entry, latex seals, hard boots, no pockets. My new DUI
CF200X/SP is custom cut, has pockets on both thighs, neoprene over latex seals,
a diagnonal front zipper and a zipper guard - very top-of-the-line and not
cheap - but I expect it to last many, many years. My Andy's suit needed new
seals after three seasons (about average) and new boots (not expected, but I
see the new boots are much heavier duty and lack the construction flaw which
became obvious when they started to leak). I really like the Andy's suit, and
would not have gotten the DUI but for a rather unique opportunity that
presented itself.

Whatever kind of drysuit you get, you should get some instruction in its use
(either from an experienced drysuit diver whom you trust, or a drysuit class)
and practice under controlled conditions before attempting any open water dives
with it.

Good luck!

-- 

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Art Greenberg
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