Evaluation of lock-out submarine “Deep Diver” for in situ biological work in boreal waters
Helgol~inder wiss. Meeresunters.
Evaluation of lock-out submarine "Deep Diver" for in situ biological work in boreal waters
R . A. CooPER ~ 1
D . J. SCAm~ATT 0 1
0 FisheriesResearch Board of Canada; St. Andrews, N,B. , Canada
1 1 National Marine FisheriesService; Boothbay Harbor , Maine , USA
EXTRAIT: Valeur du sousmarin ~l plong6e humide ,Deep Diver~ pour les recherches in situ dans les eaux bor6ales. Dans le cadre d'un programme ~ long terme, subventionn6 par le "Manned Undersea Science and Technology Office" (MUS&T) de la N O A A en rue de d6velopper les possibilit6s de travail sousmarin, six savants et techniciens de la biologie marine furent entra~n6s, ~ partir du submersible ~Deep Diver~, fi des plong6es humides utilisant des m~langes resplratoires d'air, h61ium et oxyg~ne. Un programme de plong~e satur6e ~ 45-76 m~tres, utitisant comme habitacle des plongeurs une chambre de d6compression maintenue ~t une pression correspondant ~ 45 mitres de hauteur d'eau, n'eut qu'un succ~s partM, en raison du froid p6nible auquel furent somis tes plongeurs dans une eau ~ 3,5° C et de d6fectuosit6s apparues dans l'6quipement sousmarin. Un programme alternatif utilisa la plong~e rapide, humide et non satur6e, ta d6compression commen~ant dans le sousmarin et s'achevant dans la &ambre de d6compression; il permit d'accomplir ~t peu pros tout le programme scientifique pr6vu. Au cours de 18 l~long6es rut atteinte la profondeur maximum de 87,5 m~tres. Les plongeurs prirent des photographies, r6colt~rent des 6chantillons de roches et de s6diments en vue d'analyser les contaminations par des agents polluants. I1 rut d6montr6 qu'un submersible, coupl~ avec la chambre de d6compression adapt6e, constitue un 6quipement susceptible d'aboutir ~t des observations in situ du fond sousmarin et que des plongeurs de ~ormation scientifique peuvent ~tre rapidement entra~n6s ~teffecteur sans danger des plong6es humides et ~tutiliser des techniques de plong6e hautement sp6cialis6es. scientists. There are a number of areas where, b y reasons of climate or the nature of the
I N T R O D U C T I O N
The use of diving as a tool in marine biological and fisheries science is now too
well k n o w n to require documentation. So too are depth and time limits within which
surface-oriented divers must work. A number of w e l l - k n o w n habitat programs have
effectively resolved the time constraint, at least for shallow water, and have allowed
long-term experiments and observations to be carried out b y a large number of marine
program, placement of a h a b i t a t is not an a p p r o p r i a t e method of putting divers on the
sea bed. Either the study area is too large, too exposed, the weather too unreliable, or
the p r o g r a m requires mobility. The solution is to bring the h a b i t a t a b o a r d ship allowing
for continual pressurization (storage) of the dive team with periodic transport to the
work site by diving bell, or submarine. This gives a high degree of surface control and
safety. It does not permit instantaneous sorties by any diver at any time, and if storage
and sortie depth are different, there may be restrictions on dive time. It does offer a
wider range for exploration than is available to a diver restricted to the immediate
vicinity of a habitat, by reason of the mobility of the surface support ship.
To our knowledge this is the first attempt at using a submersible with mating
deck decompression chamber (DDC) for a saturation diving program for scientific
purposes. This paper describes the equipment and methods used in the program, and
the modifications that proved necessary in the light of experience.
O R G A N I Z A T I O N
This program was the first major fidd operation of the New England
Man-InThe-Sea-Program (NEMITS) of the National Marine Fisheries Service (NMFS)
Northeast Fisheries Research Center based at Boothbay Harbor, Maine
(USA)Primary financial support of this program is from the Manned Undersea Science and
Technology Office, National Oceanic and Atmospheric Administration (NOAA),
Guest scientists from the Fisheries Research Board of Canada (3 diver/scientists),
the Environmentai Protection Agency, Kingston, Rhode Island (4 surface support
scientists), and the Maine Department of Sea and Shore Fisheries (1 surface support
scientist) were major participants in this 3-week program. NEMITS personnel totaled
8 : 4 diver/scientists, 2 surface support and 2 boat skippers. Perry Oceanographics,
Inc., Riviera Beach, Florida, the prime contractor, supplied a total of 11 people
ranging from project supervisor to medical diving officer, submarine pilot, diving officer,
vessel skipper, cook and line handlers. A total of 27 persons were involved full time or
part time in the execution of this program.
The submersible used was the two compartment, Perry-Link "Deep Diver", the
first to be designed specifically for lo&-out work. Pilot and observer occupy the
forward compartment, and the a~er compartment has space for 2 divers. "Deep Diver"
was carried in a special frame on the stern of the 38 m oil-rig service boat "State
Wave" and laun&ed and retrieved by a stern mounted A-frame gantry and win&
A double lo& decompression chamber with a transfer tunnel bolted to the after
end was mounted on de& rails and could be winched aR so that the transfer tunnel
aligned with and could be bolted to the entrance trunk of the submersible. This
allowed transfer of divers under pressure. A pressure hatch between chamber and tunnel
allowed independent use of the submarine when the chamber was occupied. The main
chamber lo& was 1.5 m i.d. × 2.5 m long.
All piping, valves and gauges were outside the chamber putting control entirely in
the hands of the on-de& operators. Gas supply consisted of L.P. compressed air from a
de& mounted compressor, giving 5660 1 at 13.6 atm, and helium, oxygen, and helium/
oxygen mixture from storage tanks, all independently controlled. Oxygen and L.P.
air could be supplied to breathing masks inside the chamber. The masks were fitted with
outboard exhausts to prevent contamination of chamber atmosphere. Other fittings
inside the chamber included a hot-water heater with water-turbine driven fan, COs
scrubber with sealed 24 v.d.c, motor and magnetic fan drive, a fire hose, a Be&man O.2
analyzer and a thermometer. Floor and wails to half height were lined with
noncombustible woven synthetic fibre mattresses and the outside was fully insulated with
about 3 cm of neoprene foam. Food, clothing and a portable to~let were locked in and
out as required.
A smaller decompression chamber (1.2 X 2.4 m) was also mounted on de& and
was available for diving emergencies if the main &amber was in use.
Support vessels (6.4 and 11.6 m) for standby diver, attendant and radio operator
were provided by NMFS.
Divers' equipment, suits, regulators, helmets, etc., were provided by the scientific
party. For lo&-out dives, Aquasport Poseidon Unisuits were used with nylon fur pile
underwear, augmented on deep dives by one or more suits of thermal underwear.
Initially, all divers used Kirby Morgan Band masks (model 8) with Helle hard wire
communications to the submarine. Later these were abandoned in favor of
conventional single hose regulators and face masks. Divers' breathing gas was supplied by
umbilical hoses from storage bottles on the submarine. Hoses, when not in use, were
coiled on racks inside the divers' compartment. Weight belts and shoulder harnesses
carried twin 280 1 bottles of breathing gas fitted with a single hose regulator for
emergency use. Divers also wore conventional fins, knives, gloves and ancillary equipment.
The standby diver wore a Unisuit and for deep dives, a KMB-8 mask supplied via
umbilical hose with breathing gas from cylinders on deck, and with hard wire
communication to the surface. In shallow water the standby diver used conventional
Underwater photography was by Nikonos camera with close-up lens and
electronic flash. On deep dives the camera was carried open in the divers' compartment
and assembled after pressurization to prevent distortion, flooding, or malfunction.
Sampling was done by hand, or with stainless steel scrapers and forceps into plastic
bottles, or canvas bags. Collecting nets and other equipment, sediment core tubes, and
underwater hand lamps were carried in a rack bolted to the port side of the submarine.
T r a i n i n g
Six divers in three teams of two were selected for training. Team 1 was
comprised of Dr. R. A. CoOV~R (team leader) and Mr. C. D. NEWELt, team 2 was Dr. D. J.
SCaRRATT (team leader) and Mr. R. A. CLIFFORDand team 3, Mr. K. J. PeccI (team
leader) and Mr. A. A. WILSON. Two had made a lo&-out dive from a submersible
before (Coov~R and SCa~RATT), and four had had experience in saturation diving
(CooPER, CLIFFORD,NEWELLand PECCI).
All six divers were thoroughly instructed in lock-out routines by the professional
submarine crew and, in addition to the support personnel, were trained in operation of
the deck decompression chambers, compressors, and ancillary equipment.
Each team made two lock-out training dives in depths of 20 m or less which gave
adequate time for thorough learning without incurring decompression penalties. Two
teams were scheduled to make the deeper dives, the third team was a backup should
any of the principal divers be unable to continue. Standby divers were selected on
rotation from the teams not scheduled to ride the submarine.
There were two significant incidents during training. Team 1 allowed a pencil to
foul the seal of the inner hatch on completion of the dive. This caused air loss and a
premature decrease in pressure in the divers' compartment as the submarine surfaced.
By opening the main gas supply the divers were able to maintain pressure greater than
their first decompression stop while the pilot re-submerged and the fault was rectified.
Team 2 had the experience of having an under-ballasted submarine surface as they
were locking out at a depth of 18 m. Both divers held onto the sub as it ascended and
re-entered once the pilot had control. No attempt was made to re-enter while the sub
was rising in case the sudden addition of weight caused re-submergence with possible
flooding of the divers' compartment or pinning divers underneath.
Thereafter all ballast and trim tanks were completely flooded before
pressurization began, and divers left the submarine at the end of the test.
All personnel were trained in submarine launch and recovery routines and most
filled the surface swimmer role of hooking up andreleasing lifting cables and steading
lines at least once. All were trained in decompression chamber operation and were
assigned tasks in rotation under the direction of the professional crew.
D i v i n g
r o u t i n e
Divers dressed either in the diving locker aboard "State Wave" or in the DDC
and entered the submarine fully dressed except for fins, masks, gloves, and weights,
which were stored in the divers' compartment of the submarine.
Following launch, the submarine maneuvered to the dive site while divers put on
fins, weights, emergency gas supply bottles, etc. When the dive site had been selected
and the submarine was firmly on the bottom, the intercompartmental hatch was closed
and dogged, and the lower hatch ("A" hatch) undogged. Ballast and trim tanks were
flooded and divers put on gloves, masks, fitted umbilicals and prepared for exit. When
all was ready, blow down (pressurization) was commenced by the diver in the forward
seat who regulated gas flow to give a pressurization rate of ca. 30 m/minute. Unisuit
inflation was from bottles of compressed air carried in the divers' compartment. Once
internal pressure equalled outside water pressure " A " hatch fell open. The forward
diver stepped into the trunk and onto the ocean bed approximately 1 m below the
gaswater interface in the trunk. Attempting to lift the submarine gave a c h e & that
the submersible was firmly on the bottom. The forward diver then exited, carrying his
hose bundle and tested that the submersible was properly ballasted. When both divers
were satisfied, they began their work routine and continued until finished or their
bottom time had expired. In areas of very low visibility, such as on flocculent mud,
only one diver was •out at a time. The after diver re-entered first (thus allowing the
dive supervisor in the forward compartment clear view of both divers as they
negotiated the entrance trunk), coiled and stowed the hose bundles and assisted the forward
diver to re-enter. When both divers were inside, both A and B hatches were closed and
the divers' compartment pressurized an additional 1 m to effect and che& on a good
seal. Thereafter ballast and trim tanks were blown and the submarine surfaced. Rate
of depressurization of the divers' compartment and decompression stops were
controlled by the dive supervisor in the forward compartment. H e also advised the surface
crew what pressure to have the D D C to effect transfer.
When the submarine had been retrieved and was secured on de&, the outer hatch
to the divers' compartment was opened, the DDC was winched aft and the transfer
tunnel bolted to the submarine. When the transfer tunnel was pressurized the inner
hatch to the divers' compartment was opened and the divers dropped through the open
hatch and entered the chamber where decompression was completed.
Diving in a saturation mode differed only in that divers lived in the DDC
between dives at a depth equivalent to 46 m breathing a 6 % Oe, 94 % He mixture, and
transfers to and from the submarine were made at that pressure. Other than that,
routines were comparable.
S c i e n t i f i c
Divers' tasks consisted of locking out at predetermined stations at 7.6 m depth
intervals between 30 m and 76.2 m. Once in the water, they were m take photographs
and qualitative samples of the substrate and all common benthic species. They were to
collect the epifauna from 929 cm2 (1 f~) areas selected at random and collect these in
numbered containers, and take in situ records of environmental parameters
(temperature, pH, O~ concentration and salinity) measured on a specially designed unit
with remote sensors, mounted on the submarine. If any time remained, a search was
made for lobsters.
All specimens collected were taken by the Environmental Protection Agency for
analysis. The principal aim was the establishment of baselines for the occurrence of
heavy metals, pesticides and industrial contaminants. Quantitative samples were for
calibration of samples taken remotely by grabs from surface vessels.
Sampling by hand was easily accomplished by all divers, and many unusual,
interesting and potentially valuable photographs were taken and observations made. For
example, there is now some evidence that shrimp, PandaIus boreaIis, burrow in soft
mud. A number were seen in shallow depressions in the mud surface in depths greater
than 60 m. One small shrimp appeared to emerge from the mud about 8 cm from a
core tube that was being inserted, and a large one was dug out of the mud by hand
while a burrow was being investigated.
A number of dry mode dives, with observers rather than swimmers in the a f e r
compartment, were made principally in a search for shrimp by personnel of the Maine
Department of Sea and Shore Fisheries, but also by Boothbay Harbor personnel
searching for lobster burrows in mud areas.
Teams 1 and 2 made a total of 5 training dives on air to depths of 70 feet (21 m)
and 11 working dives on air or HeO2 to depths of 87.5 m. Team 3 made 2 training
dives on air to 70 feet (21 m). Two other lock-out dives were made by the Boothbay
Harbor staff accompanied by MUS&T and National Geographic Society divers. Two
dives were aborted before lock-out due to problems on the surface support boat or
aboard "State Wave". These were: fouling of a support boat anchor and failure of a
main winch bearing. Dives were made on all substrates ranging from mud, gravel,
boulders to hard bedrock.
S a t u r a t i o n
d i v i n g p r o b l e m s
d i v i n g s o l u t i o n
a n d t h e " b o u n c e "
The original proposal was that a f e r completing training, two teams would spend
approximately 5 days each at 46 m depth equivalent, from which they would make
diving excursions as deep as 76 m and remain there up to one hour without requiring
decompression stops when returning to storage depth. This schedule was not
maintained partly due to problems in handling the submarine in rough water, and delays
due to equipment failure. The principal reason for la& of success in saturation diving
was failure to fully anticipate and prepare for the rapid heat loss that divers
experienced in the helium atmosphere of the submarine. Conditions in the DDC were
comfortable at 27-28 ° C. During dressing, divers would perspire heavily and
undergarments frequently became saturated. The divers' compartment of the submarine was
unheated and divers began to chill as soon as the submarine was launched. Selection of
a dive site frequently took 30 minutes (sometimes more) by which time divers were
thoroughly chilled. Heat toss was further accelerated once the divers were in the water,
which was about 3.5 ° C, breathing 85 % He, 15 % O~ mixture and the longest time
spent out was 18 minutes. Subsequently, there were problems in retrieving the
submarine due to rising seas and delay in transfer due to misalignment of submarine and
transfer tunnel. Divers became dangerously chilled and were unable to meet the
required work load. Thus the saturation experiment ran for 2 days instead of 5, only
one dive was made per day instead of 2, and decompression still took 42 hours. The
DDC was fully manned, 24 hours a day for the better part of 4 days for a total
bottom time of less than 2 man hours. This was unacceptably costly.
The problem dearly lay in the failure to ant!cipate and prepare for the heat loss
sustained by divers breathing HeO~ in 3.5 ° water. It had been assumed that Unisuits
and thermal underwear would be adequate, tt is now clear that auxiliary suit heating,
either by hot water suits or electrically heated underwear is mandatory and should
probably be augmented by heating the divers' breathing gas.
In the absence of auxiliary suit heating, the original plan for both teams to make
saturation dives was abandoned and a program of "bounce" diving adopted. This
would allow divers to dress on de& and remain in a one atmosphere, air environment
until the submarine was sitting hard on the bottom and the blowdown commenced.
There would be no helium in. the suit insulation and the divers would maintain thermal
stability right until the time they entered the water. The dive would then be nearing
completion before the divers began to feel cold.
This system worked perfectly. The constraint now was in balancing diving time
against decompression, especially at depths exceeding 60 m, so that two dives could be
made per day. With careful planning and task assignment, it was found that the work
schedule could be accomplished within 30 minutes, ascent could begin within 40
minutes of blow down. Total decompression time never exceeded 3a/4 hours. Thus two deep
dives, one by each team, could be completed in a day. Working days were still long,
but there was no need for 24-hour chamber watches. The divers were comfortable
throughout the period they were in the submarine, and total bottom time and work
effectiveness were at least doubled. Adoption of this system allowed much of the
scientific program to be completed. Even though some scheduled dive sites were not
occupied due to the limitations of the submarine handling system, dives were made in
comparable depths in other, sheltered locations where the sea was not so rough.
A number of minor delays and frustrations were due to problems with the
submarine or its handling system. For example, significant leakage in 9 of the submarine
view ports (attributed to the change from Florida to Maine temperatures) caused the
loss of 2 days diving while ports were reseated and tested. Similarly, the failure of a
winch bearing caused a loss of 2 working days. Some minor discomforts such as the
absence of an effective shelter for the DDC were the result of a Florida based
company not being aware of the climate of the Gulf of Maine in spring, and others
stemmed from the use of hitherto untried systems. None affected the safety of the divers.
The principal factors responsible for failure of the program to meet all its stated
objectives were: (1) The inadequacy of the submarine handling systems in moderate
seas. This resulted in several stations not being occupied as planned, and on occasion
caused prolonged periods of discomfort to submarine crew. (2) The failure to
anticipate and prepare for massive heat loss by saturated divers breathing HeOe caused
abandonment of the saturation diving program and its substitution by the "bounce"
dive program. This represents a setba& to the long-range plans for saturation diving
but has a&ieved an accomplishment in that the te&niques of "bounce" diving, via
lo&out submarines, for research purposes to depths approaching 100 m are now
explored and proved valid.
There is no doubt that many questions of significance in fisheries can only be
answered by direct observation on the sea floor. Some of these in deeper water can
therefore only be answered by the adoption of deep-diving techniques of the type
described herein, where divers are able to perform tasks which could not be
accomplished by remote methods from inside the submarine, They include the examination of
deep-sea spawning beds. Studies of offshore lobsters and deep-water crab populations,
trap loss and "ghost" fishing by lost but undamaged traps in offshore lobster and crab
fisheries, the effect of trawling on bottom ecology, and others. The opportunities in
pure science are infinitely wider and include questions in many branches of marine
zoology, geology, and oceanography limited only by the imagination of the
investigators concerned and their financial resources.
The program demonstrated convincingly that, given adequate equipment, diver
scientists can be trained effectively in deep diving techniques and thereaRer use these
skills in fisheries or biologically oriented research.
1. Six scientists and technicians were trained in lock-out diving from the submersible
2. A planned program of saturation diving on predetermined sites in depths between
150 and 250 feet (46 and 76 m) was only partially successful because of extreme
cold experienced by divers breathing heliox mixtures in 3.5 ° C water, and because
of inadequacies in the submarine handling system.
3. An alternate system of bounce lock-out dives permitted completion of an
abbreviated scientific program in depths down to 287 it (87.5 m).
4. Divers took photographs, rock and sediment core samples, and made collections of
common benthic species for subsequent analysis for environmental contaminants.
5. It was effectively proved that diver scientists can train rapidly for lock-out diving
programs and perform effective scientific work.
First author's address: Dr. R. A. CoovrR National Marine Fisheries Service Boothbay Harbor , Maine 04575 USA