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IANTD UK CONFERENCE 1997
Coventry - 26/27 April : Hilton Hotel
Report on Technical Sessions
-------------------------------------
The following is a personal report on Talks, Workshops and Trade Exhibitions
seen at the IANTD UK Conference this weekend. I will try & present a synopsis
of what I heard & saw. If you disagree with any of the content or views
presented then by all means post your alternative views but please don't flame
me. I am simply recording what was seen & said and make no comment here on
any statements made by others.
I have taken a number of photographs from the conference of items such as the
AP
Valves Inspiration & Cis-Lunar Mk.5 rebreathers. I can scan these pictures in
to my computer but as yet I haven't gotten around to making up a web page for
myself. If anyone is willing to put a few of these pictures up on their own
web
page so that anyone can view them then please let me know.
SATURDAY APRIL 26TH
********************************************************************************
OPENING ADDRESS
Kevin Gurr, the Conference Organiser and present Chairman of IANTD-UK, opened
the Conference on the Saturday and welcomed all the delegates attending. The
numbers at Coventry were an increase on the 1996 Conference at Swindon, which
may be a reflection of the geographically more central location of the
conference this year or of the increasing popularity of technical diving in the
UK.
Kevin managed to plan the Conference during some miserable wet & windy English
weather & poor tides so that everyone felt well satisfied with sitting inside
for 2 days rather than going out diving.
********************************************************************************
GAVIN NEWMAN MALLORCAN CAVE DIVING
The 1st technical presentation was made by Gavin Newman, who is well known as
a
cave diver and accomplished photographer on the UK and international scene.
Gavin began his talk by describing his personal learning curve into the world
of
cave diving under the likes of Sheck Exley, Rob Palmer & Martyn Farr. As a
photographer, his skills were often in demand and led to his being frequently
invited on expeditions that otherwise may have been out of reach. The talk
reviewed the development of cave diving techniques and some impressive slides
were shown from caves in Yorkshire (UK), the Swiss Alps and China. Gavin then
focused upon more recent cave diving expeditions in Mallorca. off the coast of
Spain with fellow cave divers Steve Thomas, Phil Short and Owen Clarke (still
cave diving at the age of 70 !) . The presentation was concluded with the
first
public viewing of a superb 10 minute audio-visual slide presentation called
'Hidden Earth'.
********************************************************************************
TOM EASSOP BIKINI ATOLL
Tom Eassop gave a talk describing the diving that has recently become possible
on Bikini Atoll, the site of USA atomic bomb testing some 50 years ago. The
underwater shipwrecks diveable include the aircraft carrier 'USS Saratoga'
which was deliberately atom bombed after the end of WW2 to study the
effectiveness of atomic weapons in taking out a military navy. Diving was
conducted in excellent visibility and warm water. One slide showed a clear
shot
of the sun taken from 170 feet underwater (!). The USS Saratoga lies in a
depth
of 140' to 180' and is upright and still pretty much intact, in spite of its
sinking with an atomic bomb. Slides were shown showing the aircraft deck,
bowed
by the weight of water falling onto it immediately after the atomic explosion.
Penetration diving is possible through wide passageways some 800' long in 100'
of visibility. The main problem presenting technical divers was that of rust
dislodged by exhalation bubbles & degrading the visibility. Slides were shown
of ordnance left on deck and 5'' guns, together with an impressive shot of the
bow of the aircraft carrier taken from some distance off the front of the wreck.
In total some 7 WW2 wrecks can be dived on Bikini Atoll, comprising one
aircraft carrier, 2 battleships, 2 destroyers and 2 submarines. Diving is in
the range of 70' to 180' and is all done using air.
Tom finished his talk by showing some of the post atomic recovery of Bikini
Atoll above the water. Gamma radiation is still present but the dosage
encountered by divers on a 1 week expedition was too low to be a concern. The
coconuts growing on the island however collect an abnormal amount of radiation
and should not be eaten....nor should the sludge from around the vicinity of
the
wrecks !! :-)
********************************************************************************
RICH PYLE/BILL STONE CIS-LUNAR MK.5 WORKSHOP
Following these 2 formal talks there were 2 parallel workshops on Decompression
Software and the Cis-Lunar Mk.5 rebreather. I attended the rebreather session.
Rich Pyle gave a rundown on the functionality of the Cis-Lunar Mk.5 unit, the
first one to be seen in the UK.
He began by showing the features of the breathing loop. The patented
lightweight mouthpiece incorporates a combined closed circuit and open circuit
capability which can be changed simply by rotating a large switch on the front
of the mouthpiece. The counterlung is split, with inhalation and exhalation
lungs located on the right hand and left hand sides and is wrapped over the
shoulders of the diver. This, Rich explained, allowed the same breathing
resistance in any diver orientation and the split facility enabled the
hydrostatic water pressure to equalise the lungs on exhalation and reduce the
overall breathing resistance. The counterlungs can be adjusted by +/- 30
degrees and up/down by 4'' to facilitate the optimum breathing position for the
diver. The breathing hoses were doubly armoured to protect against any
accidental damage and incorporated water traps, one each shoulder, to divert
any
water present in the loop into the counter lung.
Rich then moved on to a description of the CO2 scrubber unit, the O2 sensors
and
the diluent injectors. The 3 sensors were located just after exhaled gas
leaves the scrubber unit and had a sponge absorber below them which would
collect any moisture which made it past the water traps (e.g. from condensation
of the diver's exhaled gas). Each sensor had a diluent injector pointed
directly at it. This arrangement was designed so that each injection of
diluent
would act to dry off any moisture which was lying on a sensor and which might
compromise its accuracy. The scrubber unit itself was surrounded by a 100%
water resistant membrane that could withstand a hydrostatic water pressure of
10
metres. It would be technically possible Rich explained to replace a scrubber
unit underwater during a shallow deco stop without any water contaminating the
scrubber material inside the unit. The water in the connectors can then be
flushed
out of the system, as with any sort of flooding event. This water resistant
capability meant that Lithium Hydroxide, which reacts violently on contact with
water could be used as a scrubber material. Rich then went on to show how the
3
O2 sensors could be easily removed from the top of the scrubber unit for
inspection. drying or replacement.
The next part of the rebreather to be described was the gas switching block.
Two switches allow both the oxygen and the diluent to be switched between the 3
litre and 2 litre cylinders housed within the rebreather and any off-board
cylinders located either externally on the sides of the rebreather or
side-mounted on the diver. The gas block can also be used to isolate any
on-board or off-board cylinder and can be used for manual injection of either
oxygen or diluent into the breathing loop. On the font of the gas switching
block was a special 'multi-function switch'. A two-handed pull and 45 degree
turn enabled the oxygen feed to the injector solenoid to be isolated in the
event that it ever failed in a jammed open condition. Turning the same switch
to a 90 degree position allowed 100% oxygen to be supplied to the open circuit
bailout regulator, built into the mouthpiece.
The automatic diluent injection module was then displayed. This would feed
diluent into the breathing loop when the counterlung deflated. However it
could
also be immobilised to prevent accidental diluent injection during a deco stop
on 100% oxygen.
Finally Rich described the electronics of the rebreather. 3 independent
processors, each with their own battery supply were networked together and
continually checked each other for correct functioning. Each processor senses
up to 4 cylinder contents pressures (2 in-board & 2 off-board), 2 depth sensors
and 3 ppO2 sensors. In addition the was a secondary unit (with its own
battery)
which senses and displays the 3 ppO2 sensors. This unit is located on the back
of the primary display unit. The primary display unit (with its own
independent
battery...that makes 5 batteries in total !) shows depth and decompression
information together with 3 ppO2 values, O2 CNS and OTU build-up and various
system info data. The primary unit can be used to change the ppO2 set point
during the dive, to change the display font size, to program 5 different
breathing mixtures, to enable full open circuit bailout trimix decompression
calculations, to alter contrast & backlighting of the display and to access a
whole series of menu options.
In addition to the primary display unit, 3 LED's were positioned in front of
the
diver's mask to provide a head up display (HUD) that the rebreather is
functioning correctly. The LED's could change colour from green to yellow & to
red & could be constant or flashing. They are used to indicate that
decompression, oxygen and system parameters are all OK. They are all very
bright but their intensity can be adjusted to suit the diver. An audio alarm
is
also used to give warning of a ppO2 problem.
So far, 30 units have been purchased & built and will be delivered to their
owners by June 1st, this year. In addition a further 35 units have been
ordered
so far & their expected delivery date is later this September.
The Mk.5 sells for $15,000 US. Training courses will initially only be held in
the USA and are an additional expense.
********************************************************************************
BILL STONE CIS-LUNAR CAVE DIVING EXPEDITIONS
Following the Workshop sessions, a formal talk was presented by Bill Stone
describing past cave diving expeditions using Cis-Lunar rebreathers. Bill
outlined some early cave diving trips in Mexico in the 1970s using open circuit
breathing equipment. A series of wet and dry expeditions were carried out with
increasing depth & penetration. In 1981 these culminated in 3 to 4 day trips
underground and resulted in some 2.5 km of penetration and 300m of depth. It
was
felt however by Bill Stone that the logical limit of safe open circuit diving
capability was being reached and that the development of a closed circuit
facility was the way forward.
Since 1987 to date there has been a continual development by Bill of
rebreathers, beginning with the original 'Mk.1' and culminating in the 'Mk.5',
now commercially available. The Mk.1 was used in the Wakulla 1 expedition and
showed that a 24 hour redundant capability was possible. The prototype unit
was
however impractically large, heavy & cumbersome and was replaced by improved
Mk.2 & Mk.3 units.
By 1993 the Mk.4 rebreather had been developed with a 6 hour capability and was
used in Jackson Blue Spring to penetrate some 1.3 km into the cave.
In 1994 Bill returned to Mexico with an expedition using 9 Mk.4 rebreathers.
During a period of 3 months trips living underground of up to 3 1/2 weeks were
spent pushing a series of sumps. The talk showed quite hard living conditions
but over 1 mile of new (dry) cave was explored. During the 3 months a cave
depth of 1475m and penetration of 6.5 km was reached. Unfortunately one of the
expedition members, Ian Rollands, died during the expedition from a medical
condition which was believed to be unrelated to either equipment failure or the
cave conditions.
Bill plans to return again to Mexico for the 1999 San Augustine Expedition.
Regards, Steve M.
**************************************************************************
* * *
* Dr. S. G. Millard, * E-Mail : ec96@li*.ac*.uk* *
* Senior Lecturer, * *
* Department of Civil Engineering * Tel : 0151 794 5224 (UK) *
* University of Liverpool, * 44 151 794 5224 *
* PO Box 147, * (International) *
* Liverpool L69 3BX, * *
* UK. * Fax : 0151 794 5218 (UK) *
* * 44 151 794 5218 *
* * (International) *
* * *
**************************************************************************
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