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Andrew Poole (left) using a dual, scooter-mounted rebreather (with a second rebreather for emergency use on his back) and Mike Bruic (towed by a Fatman Scooter and trailing a backup Thinman Scooter) enter the Wakulla Spring cave [photo ©1998 US Deep Caving Team, Inc.]. |
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Unfortunately, Andrew and
Mike's dive was cut short by a water leak in the
scooter-mounted rebreather. Back on the surface the rig was
taken apart. Bill Stone (smirking in the photo) and Jim
Schlesinger found the source of the leak--a brand new check
valve. This extra bit of hardware is needed in the vehicle
mounted rebreather to account for pressure changes that take
place in the final ascent of a mission. Before entering the
PTC (personnel transfer capsule) the vehicle-mounted MK5 and
the back-mounted MK5 must be doffed. To simplify this
maneuver, underwater pluggable breathing hoses (see below)
were developed for the project. When these are disconnected
(see bottom photo) there is no breathing bag (counterlung)
attached to the rebreather mounted on the vehicle. Ascending
directly to the surface without venting the excess pressure
inside the rebreather would lead to a rupture of the
housing. The overpressure vent eliminates that problem. The
rig will go back in the water tomorrow with a more reliable
venting system [photo ©1998 Barbara Anne am
Ende].
