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WINTER 2014
CLOSED CIRCUIT:
Tech diving requires manually
operated rebreathers. Some rebreathers are always
manual (mCCRs); others automatically control
functions (eCCRs) but allow manual operation in
contingency situations.
• One or more open-circuit bailout bottles. These
contain enough bailout gas to allow the diver to
safely reach the surface, but they’re used only if
the CCR fails. The deeper or more distant the
dive, the more bailout required.
• Off-board gas supply (additional rebreather gas
stored externally to the unit)
• Most CCRs have unit-specific BCDs and
harnesses.
Other gear used in tech diving includes drysuits,
which are worn in all but the warmest water due
to dive duration, and tech computers, which are
designed to calculate trimix decompression and
accommodate multiple gases for open- and closed-
circuit diving. Tech divers always have two (one or
both may be built into an eCCR). Cave and wreck
penetration require reels for running a line to the
exit. Reels may also be used to send up markers.
BECOMING A TECH DIVER
Tech diving commonly requires multiple
qualifications. For example, cave diving to 400 feet
using a CCR requires qualifying in CCR diving, the
particular CCR used, cave CCR diving, at least three
levels of deep CCR diving and drysuit diving. The
certifying organizations have different levels, but
here’s an overview:
Prerequisite: Tech divers begin as recreational
divers with at least some training beyond entry-level,
including basic enriched air nitrox.
OPEN-CIRCUIT DEEP
• First level — Backmount or sidemount with one
or two deco cylinders for air/enriched air nitrox
decompression diving to the 130-foot range
• Second level — Trimix and multiple deco gases to the
200-foot range
• Third level — Hypoxic trimix (not breathable at the
surface) and deco gases to the 300-foot range
CLOSED-CIRCUIT DEEP
• First level —Using a tech CCR with a bailout for
primarily no-decompression diving to the 130-foot range
• Second level — Using a tech CCR with trimix and two
bailout cylinders to the 200-foot range
• Third level — Using a tech CCR with hypoxic
trimix and three or more bailout cylinders to the
300-foot range
• Fourth level — Exploratory CCR below the 300-foot
range (very few divers qualify to this level)
Note: CCR training is unit-specific; divers qualify on each
type of CCR. You don’t have to be an open-circuit tech
diver before becoming a CCR tech diver.
CAVE DIVING
• Cavern — Using standard recreational equipment in
the cavern zone (within 130 feet of and within sight of
light from the surface)
• Level one — Using full or partial cave gear beyond the
cavern zone but within the range of a single cylinder
• Level two — Using full cave gear and diving within the
range of double cylinders
• Level three — Using stage cylinders to extend range
Note: Most divers learn to cave dive with open-circuit
and then become CCR cave divers after independently
qualifying for both cave and CCR.
KARL SHREEVES/COURTESY PADI
STEPHEN FRINK
