7-12 Change A
U.S. Navy Diving ManualVolume 2
Dry Suits. The Variable Volume Dry Suit (VVDS) has proven to be effective in
keeping divers warm in near-freezing water. It is typically constructed of 1/4-inch
closed-cell neoprene with nylon backing on both sides. Boots are provided as an
integral part of the suit, but the hood and three finger gloves are usually separate.
The suit is entered by means of a water- and pressure-proof zipper. Inflation is
controlled using inlet and outlet valves which are fitted into the suit. Air is
supplied from a pressure reducer on an auxiliary cylinder or from the emergency
gas supply or the scuba bottle. About 0.2 actual cubic foot of air is required for
normal inflation. Because of this inflation, slightly more weight than would be
used with a wet suit must be carried. Normally, thermal underwear can be worn
under the suit for insulation.
Gloves. Gloves are an essential item of protective clothing. They can be made of
leather, cloth, or rubber, depending upon the degree and type of protection
required. Gloves shield the hands from cuts and chafing, and provide protection
from cold water. Some styles are designed to have insulating properties but may
limit the divers dexterity.
Wet or dry suits can be worn with hoods, gloves, boots, or hard-soled shoes
depending upon conditions. If the diver will be working under conditions where
the suit may be easily torn or punctured, the diver should be provided with addi-
tional protection such as coveralls or heavy canvas chafing gear.
Writing Slate. A rough-surfaced sheet of acrylic makes an excellent writing slate for
recording data, carrying or passing instructions, and communicating between divers. A
grease pencil or graphite pencil should be attached to the slate with a lanyard.
Signal Flare. A signal flare is used to attract attention if the diver has surfaced
away from the support crew. Any waterproof flare that can be carried and safely
ignited by a diver can be used, but the preferred type is the MK 99 MOD 3 (NSN
1370-01-177-4072; pouch is NSN 1370-01-194-0844). These are day-or-night
flares that give off a heavy orange smoke for day time and a brilliant red light at
night. Each signal lasts for approximately 45 seconds and will withstand submer-
sion up to depths of 200 fsw without adverse effects. A hexagon shaped end cap
marked SMOKE is threaded into the smoke assembly and a round shaped end cap
with eight grooves marked FLARE is threaded onto the flare assembly. Also
available are the MK 131 MOD 0 (NSN 1370-01-252-0318) and MK 132 MOD 0
(NSN 1370-01-252-0317). The MK 131 is for day time distress signaling while
the MK 132 is for night. The only difference between the MK 99 and the MK
131/132, other than the fact that the MK 99 is a combined day/night signal flare
which gives off yellow smoke and light, is that the MK 99 satisfies magnetic effect
limits of MIL-M-19595 for explosive ordinance disposal (EOD) usage. Flares
should be handled with care. For safety, each diver should carry a maximum of
two flares. All divers/combat swimmers engaged in submarine Dry Deck Shelter
operations should stow flares in hangar prior to reentering the host submarine.
Acoustic Beacons. Acoustic beacons or pingers are battery-operated devices that
emit high-frequency signals when activated. The devices may be worn by divers to
aid in keeping track of their position or attached to objects to serve as fixed points
of reference. The signals can be picked up by hand-held sonar receivers, which are
used in the passive or listening mode, at ranges of up to 1,000 yards. The hand-
held sonar enables the search diver to determine the direction of the signal source
and swim toward the pinger using the heading noted on a compass.