Update
on the Science Lung II
by
Dr. Patrick Colin
Since earlier in the project, there hasn't been any
direct mention of how my "homemade" rebreather,
the "Science Lung II" has been doing. I have
now done 6 deep dives with the Science Lung II, or SL2,
with great success. Except for one "shallow
dive" to 220 feet, the other dives have been made to
300-330 feet with bottom times of 10-15 minutes. With
decompression, total dive time is 2-2.5 hours. The
longest dive so far for me has been 180 minutes, of which
the last 30 minutes I just stayed down on oxygen to get
more time on the scrubber.
The SL2 is a closed-circuit mixed gas rebreather with
electronic control of oxygen partial pressure. The SL2
was designed for use in studies of reef fish reproductive
activity in relatively shallow water, the design
parameters were for a fully mixed-gas capable electronic
unit with 3-4 hour duration on scrubber, oxygen and
electrics. While my research needs were primarily for
relatively shallow-water use (less than 100 feet), the
unit was also designed to be capable, using appropriate
inert gases, to as much as 400 feet. The SL2 has no
integrated decompression computer, so decompression has
to be determined by tables, using depth and time
information.
The SL2 has been a long-term interest for me, but I
went through a long period of having no research mission
for a mixed-gas rebreather. I was originally inspired by
the work of Walter Starck and his associates in the late
1960's and early 1970's. I completed my first mixed-gas
rebreather (the Science Lung I) in 1978, but did not use
it extensively due to unreliable oxygen sensors. In 1989
I renewed my interest in rebreathers and using the
lessons learned from my original unit, designed the SL2
to specifically meet my needs. The unit is constructed
primarily of molded fiberglass and PVC plastic with a
chest-mounted counter lung. The complete unit ready to
dive weighs 47 lbs and is streamlined, neutrally buoyant
and statically neutral in sea water. It is not intended
for commercial development or production; strictly for my
own scientific research. The realities of liability and
diver-induced errors make anything beyond that out of the
question. For these reasons, no details regarding the
unit will be available. With about 20 hours of deep mixed
gas and decompression on it now, I feel the unit is
reliable (but not yet to be trusted-that is far in the
future) and in the right hands can be a tool to do things
that would otherwise be impossible.
I have been able to collect quite a number of
interesting invertebrates at depth during this project
and in combination with those stalwart invertebrate
grabbers, John Earle and Rich Pyle, we have found quite a
number of new invertebrate taxa. Unfortunately with most
invertebrate groups (as opposed to fishes) it is hard to
say instantly that some specimen is a new species or
whatever. But I have been able to take quite a few high
quality 35 mm slides of organisms at depth using the SL2
and a few of these will be shown here in low resolution
form.
|
