__ Salvage of USS SQUALU5 E.
APPENDIX
E♦ Salvage of USS 5QUALUS
E.1. Submarine Sunk
On 23 May 1939, USS SQUALUS was on training operations
near Portsmouth, New Hampshire. While making a quick dive
at 16 knots, water suddenly entered the engine room and
after battery compartment through the air induction line.
The submarine settled stern first and came to rest on the
bottom in 240 feet of water. The watertight door between
the control room and the after battery room was closed
after an estimated 50 tons of water had entered the
control room.
SQUALUS had an up angle of about 6 degrees and no list.
The after battery room was known to be flooded, but the
condition of the two engine rooms and the after torpedo
room was unknown. Thirty-three men were in the three for¬
ward compartments. No response could be obtained from the
twenty-six men in the after part of the ship. Main
ballast tanks were blown, but the submarine could not
regain positive buoyancy. During the next 4U hours,
thirty-three survivors in SQUALUS were rescued by the
McCann rescue chamber. The operation then became one of
salvage .
E.2. Salvage Plan
E.2.1. Submarine Condition
Upon completion of the rescue operation, it was apparent
that all of the four after compartments were flooded and
open to the sea. Survivors reported that the main ballast
flood valves and emergency vents were open, the main vents
were closed, all hatches and other hull openings forward
were secured, and from the after battery compartment for¬
ward, there was watertight integrity. It was also reported
that flooding appeared to have taken place through the
main induction valve. (See figure E-1 for the arrangement
of compartments and tanks.)
While the divers were attaching the rescue chamber's down¬
haul cable to the after torpedo room hatch during the
rescue operations, they reported that the superstructure
deck at the hatch was only about 2-feet above the bottom.
This meant that the base line of the submarine at this
point was about 20-feet deep in the clay bottom.
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Salvage of USS SQUALUS E.
It was later ascertained that the keel of the ship was
clear of the bottom for about 70 feet at the forward end.
E . 2.2 . Salvage Factors
In devising a salvage plan, the following factors were
considered :
1. Except in an emergency involving human life, the
maximum time allowed for a diver on the bottom or on the
submarine at the 240-foot depth was to be 20 minutes.
This precluded sending divers inside the submarine.
2. Only one diver would be allowed on the bottom
at one time, except in an emergency.
3. Heavy physical labor could not be performed by
divers in such depths, which ruled out any efforts to
close the main induction valve before the first lift.
4. The ship was provided with high and low salvage
air connections for all compartments and with salvage air
connections to the tops of all main ballast and fuel oil
tanks. y_
5. Except for the open induction valve, the ship
was in normal condition for submerged operation.
6. The weight of water inside the ship could be
estimated with a fair degree of accuracy.
7. Two 60-ton and seven 80-ton submersible pontoons
were available.
8. It was known that a cable clamp had been designed
by Portsmouth for use with wire rope slings and tested
satisfactorily on 5-4.
9. With the emergency vents open, the three main
ballast tanks on each side of No. 2 and No. 3 group would
each act as a single tank about 45 feet long, with flood
valves distributed throughout its entire length.
Because of this flood valve distribution, the amount of
water which could be blown from these tanks decreased as
the trim angle of the ship increased. At 2D degrees,
about three-quarters, and at 30 degrees, about one-half
of the buoyant capacity of these tanks could be recovered
after one end had been lifted. About 90 percent of the
main ballast tank buoyancy could be recovered during
breakout.
E-2
Salvage of USS SQUALUS E.
ID. lYlore than 9D percent of the buoyant capacity of
the fuel oil tanks could be recovered.
E . 2.3 . Salvage method
In order to reduce the possibility of slow flooding of dry
compartments, hoses mere attached and the internal pressure
was built up to equal sea pressure. So far as could be
ascertained, no further flooding took place. Consideration
of the above factors led to the following salvage method:
1. Employ the buoyancy of all main ballast and fuel
oil tanks.
2. Lift the ship in three stages of about SO feet
each. For this lift, the trim angle would not exceed a
maximum of 20 degrees. At this angle, slippage of the
slings was considered improbable and preventers would not
be required.
3. Do not dewater the after compartments or the
variable ballast tanks while the submarine is in deep water.
4. Provide external lift needed to supplement the
self-lift of the ballast tanks using two groups of pontoons,
one group forward where slings could be swept under the
ship, and one group aft. UJith this arrangement, only one
tunnel was needed for the after slings.
5. Wash the sling tunnel at frame 180 where the depth
of the keel was about 15 feet below the mud. The shape of
the keel at this point was such as to limit the amount the
sling could slip along the bottom. It was estimated that
a lift in excess of 500 tons could be applied at this loca¬
tion without damage to the submarine, provided the slings
were placed between the hull and the propeller shafts.
6. Lift the stern first because more self-lift could
be maintained by the main ballast tanks while the ship was
on the bottom than could be maintained if either the bow
or stern were lifted. The amount of this additional lift
was about 80 tons and it would be a valuable asset while
breaking out the stern, but would not be needed after the
stern had been broken out.
7. Limit the height of the lift of each end to the
desired 80 feet by placing control pontoons 80 feet below
the surface. When the control pontoons reached the surface,
the submarine would stop and be suspended in the slings
80 feet off the bottom.
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Salvage of USS SQUALUS E.
8. Use wire rope slings, with a 15-fathom shot of
chain in way of the hull to take the chafing. This
arrangement involves less weight than chain slings and
requires less work by divers in setting the pontoons.
9. Place pontoons athwartships for the first two
lifts. This simplifies setting the pontoons by permitting
the two ends of a single sling to be placed through the
two hawsepipes of a single pontoon. The placing of each
pontoon can then be completed independently of any other
pontoon. This can be accomplished only if the ship is to
be lifted part way to the surface. If she is to be complete¬
ly lifted to the surface at a draft that will permit her
to enter a harbor, the pontoons must be placed parallel to
the axis of the ship and set simultaneously as they must
share a pair of slings.
ID. Arrange the slings and pontoons as shown in
Figure E-2 for the first lift. Calculations indicated that
the stern could be lifted first with a reasonable margin
of lift for bottom breakout and the bow could be lifted
in the next operation.
11. Tow the ship toward shallow water after the first
lift and ground her in a favorable spot. The control
pontoons would then be lowered 80 feet below the surface
and a second lift made in the same manner as the first.
The ship would again be towed toward shallow water and
grounded again, this time at about the 80-foot depth.
12. Bring the submarine to a draft of less than
40 feet in the third lift so she could be towed to the
Portsmouth Wavy Yard for drydocking. For this lift, the
induction valve would be closed by divers by means of the
external gagging gear. The water in all flooded compart¬
ments would be pumped out by the salvage pump on the rescue
vessel through the low salvage air connection. Pumping
required only that hoses be connected to the compartment
low salvage air connections and that air be fed to the
flooded compartments through the high connection at a
pressure equal to sea pressure. By pumping rather than
blowing, the work of making the compartments capable of
holding an internal pressure higher than sea pressure
could be avoided. Pontoons placed parallel to the axis
and close to the ship would be used to make up any
additional lift required.
E . 3 . Salvage Force
A large number of vessels are required to support a salvage
operation and SQUALUS salvage was no exception.
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Salvage of USS SQUALUS E.
O
The following vessels were made available:
1. USS FALCON - salvage vessel - used as a diving
platform, and actual salvage work was performed from it.
2. USS UJANDANK - tender for FALCON - assisted FALCON
when mooring, and helped to maintain her position when seas
and wind threatened the security of the moorings.
3. USS SAGAMORE - tender for FALCON.
4. USS SACRAIY1ENTQ - flag ship - provided quarters for
divers and salvage force and stored material until required
by FALCON.
5. CG 409 & 410 - dispatch boats - made regularly
scheduled trips between Portsmouth Navy Yard and the
salvage area.
6. CG 991 - work boat - towed pontoons, placed
anchors, etc.
7. USS SCULPIN - a sister ship from the same building
yard - practice ship for divers and model to check position
_ of valves and other equipment, as well as to rehearse
operations to be performed underwater.
8. PENEC00K - harbor tug.
E .4 ■ Diving Gases
When diving operations on SQUALUS began, difficulties
were encountered. The divers were experiencing nitrogen
narcosis while diving to the depth of 240 feet. It was
decided to employ the helium-oxygen breathing mixture that
was under research at the experimental diving unit.
Although the research work had not been completed, the
equipment necessary to dive with this helium-oxygen mixture
was available, and tests had already demonstrated that such
a gas mixture was definitely better than air at deep depths.
(Refer to Paragraph 2.2.) The use of these gases required
the divers to wear special electrically heated underwear
since the gas mixture was a better heat conductor than air.
E . 5 . Pipe Lance
A sectional pipe lance bent into the arc of a circle and
of the correct diameter to pass around the hull inboard of
the shafts was used to get a messenger line under the stern.
E-5
E-6
Salvage of USS SQUALUS E.
~ .
The end of the lance was equipped with a self-propelled
nozzle similar to the one used in washing out tunnels.
A series of reaction jets were added along the lance to
assist in forcing it through the mud.
A water hose was attached to one end of the lance and a
diver guided it in the desired direction. Ulhen it was
believed that the lance had come up to the surface of the
mud on the opposite side of the submarine, air was forced
through the lance. A diver then located the nozzle by
following the stream of bubbles emitting from it. Once the
lance was passed under the submarine, a steel snake was
run through it and used to pull a messenger line through.
The messenger line was then used to pull a larger line for
the sling under the submarine. This, in turn, was used to
pull out the lance and to haul under the submarine a
1-inch wire reeving line.
E.6. first Lift Attempt - 13 July 1939
The pontoon arrangement for the first lift attempt involved
seven pontoons (figure E-2). At the stern were three lift
pontoons and two control pontoons. The bow had one lift
and one control pontoon.
The control pontoons and fuel oil tanks No.'s 3, 4 and 5
were blown in preparation for the first lift. The
remainder of the stern pontoons were blown next. Then,
starting aft and working forward, the main ballast tanks
and remaining fuel oil tanks were blown in succession.
As No. 1 fuel oil tank was being blown, the stern started
rising. The two control pontoons came to the surface and
their slings went slack. Momentum of the submarine had
made it continue to rise after the lift of the upper
pontoons was lost, but it soon settled back on the slings
and the control pontoons supported some of the load with
the stern 80 feet above the bottom.
With the stern lifted, main ballast tanks 1 and 2 were
blown in that order. While blowing No. 2 main ballast
tank, the bow started rising. The control pontoon reached
the surface and about 30 seconds later the lower lift
pontoon rose up beneath it, followed by the bow of SQUALUS
(figure E-3). At this time the large up angle caused the
stern slings to slip forward along the keel and the sling
with the two lowest pontoons parted, probably due to the
dynamic loading when the sling was stopped by the after
stern tube bearing.
E-7
E-8
Salvage of USS SQUALUS E.
The loss of buoyancy at the stern permitted the stern to
sink and the submarine slipped back out of the forward sling
which was now slack. The large up angle which was exceeded
(45 degrees) caused air to spill from main ballast tank
No. 2. This, together with the loss of the bow pontoons,
permitted the bow to sink also. The attitude of the ship
when she reached the bottom was nearly identical to its
original attitude.
There was some damage to the pontoons that had collided
with one another, and damage and entanglement of many hoses.
It was decided to remove the remaining stern slings for
careful inspection. An attempt was made to disentangle the
hoses, but this proved too difficult. The original hoses
were cut away and new hoses rigged. All hoses to the ship
were replaced.
The failure of this attempt was caused by a lack of
sufficient control at the bow. The margin of control over
that dictated by the static calculations proved to be
inadequate. UJhen the ship had been raised and a post
salvage inspection made, a small leak was discovered between
No. 3 main ballast tank and the flooded compartments.
This apparently caused partial dewatering of the after
- torpedo room, while the stern was up and the No. 3 main
ballast tank was blown. When the bow rose, free surface
caused the bow to become too light. Whether or not the
single bow control pontoon would have been adequate had this
leak not existed, is not known, but the delay caused by this
unsuccessful attempt was much greater than was anticipated
when the risks had been considered prior to the first lift
attempt.
E . 7 , Revised Salvage Plan
The salvage plan was modified to provide additional
pontoons for lift control. At the stern, six pontoons
would be used: three control pontoons at the 80-foot depth,
one lift pontoon at 160 feet depth, and two lift pontoons
at 200 feet depth. Four pontoons would be used at the bow:
three control pontoons at 74 feet and one lift pontoon at
194 feet (see Figure E-4). The additional pontoons near
the surface were considered sufficient to control each end
after the desired 80-foot lift. The low pontoon at the bow
was placed near the ship so that in case the slings started
to slip aft, it would strike the bridge and thus limit the
distance the sling could slip. The bow slings were placed
aft of the bow planes and a preventer lashed the slings
close to the sides of the ship so as to prevent them from
sliding forward since the bow planes were in the rigged out
position.
E-9
Salvage of USS SQUALUS E.
E.8. Successful First Lift - 11 August 1959
After one month the ship was ready to be lifted in accord¬
ance with the revised salvage plan. The preliminary step
consisted of blouing two of the upper pontoons at the bow,
and the three upper pontoons at the stern. This was
followed by blowing the third upper pontoon at the bow and
No. 3 main ballast tank. The remaining three pontoons at
the stern were then blown in succession. As the last
pontoon at the stern was being blown,the stern started to
rise. The three upper stern pontoons broke the surface
and settled down barely awash. Fuel tank No. 5 was then
blown to provide additional buoyancy.
The lower bow pontoon and fuel oil tank No. 1 were blown
and the bow started up. By not using the main ballast
tanks forward, the gain in buoyancy as the bow rose was
limited to the capacity of the fuel tank being blown when
the submarine started rising. Because of the small pipe
size through which the water was expelled from the tank,
the gain in buoyancy was not rapid. The three upper pontoons
came to the surface and settled down awash. To gain
additional buoyancy, forward fuel oil tank No. 1, main
ballast tank No. 1, and part of fuel oil tank No. 2 were
blown.
E . 9. The Tow
UiANDANK picked up the stern towing line and got underway
assisted by the tug PENACOOK and a Coast Guard dispatch
boat. FALCON slipped her moorings and took the bow line of
SQUALUS. This was to assist FALCON in maintaining position
and prevent parting of air hoses.
SQUALUS grounded on a bank about 3-1/2 miles south of ll/hite
Island Light. The pontoons and tanks were then flooded to
set her on the bottom. The three upper stern pontoons
remained on the surface, but the upper bow pontoons went
down about 20 feet, indicating SQUALUS was resting on a
sloping bottom. Five temporary moorings were planted for
FALCON, three at the stern (windward) and two at the bow.
E.10. Resetting the Pontoons
The three upper pontoons forward were reset to a depth of
105 feet. Two of the upper pontoons at the stern were
lowered to 80 feet. This put them level with the one that
was at 160 feet on the second lift. Since there was no
large breakout requirement, the other pontoon at the stern
was removed, leaving five pontoons connected to the stern
(see Figure E-5 ) .
E-10
E-ll
Salvage of USS SQUALUS E.
E . 11. Second Successful Lift - 17 August 1939
The pontoons were set and preliminary blowing for the
second lift was completed by evening of 16 August 1939.
Two of the upper pontoons at the stern, fuel tanks 5, 4
and 3, and two of the upper forward pontoons were blown
in that order .
The following morning, the third upper after pontoon was
blown. Main ballast tank No. 3 was then blown. A lower
pontoon at the stern was being blown when the stern lifted.
The last stern pontoon was blown to ensure sufficient
buoyancy.
As soon as the stern pontoons were secured, the remaining
two pontoons forward were blown, followed by fuel tanks
No.'s 1 and 2. Main ballast tank No. 1 was blown, but
when the bow did not lift, it was reflooded, and main
ballast No. 2 was blown. The bow rose while main ballast
No. 2 was being blown. Uihile the blowing was in progress
to lift the bow, it was noted that the stern pontoons were
being unloaded gradually. Main ballast tank No. 3 was
partially flooded to keep the stern pontoons at about
half buoyancy.
It was later discovered that the bow slings had slipped
aft until the lower bow pontoon struck the bridge. Later
analysis revealed that because of the sloping bottom, the
angle of the ship while the stern was up was about 29
degrees and the slope of the keel forward about 22 degrees.
E.12. Second Tow
Shortly after the tow got underway, the bow line from
SQUALUS to FALCON parted. An 8-inch manila hawser
connected to one of the bow pontoons prevented FALCON from
drifting too far away from SQUALUS. A second hawser was
connected to the other end of the pontoon to place an equal
strain on each end and prevent pulling it out of position.
SQUALUS grounded in 92 feet of water in the location
previously selected, bearing 282 degrees true, distance
1.6 miles from UJhite Island Light. Tanks and pontoons were
flooded to set the submarine on the bottom, the stern
pontoons submerging about IQ feet.
E.13, Preparation for Final Lift
In the shallower depth, the divers could perform more work,
and it was decided to remove all hoses and to clear the top¬
side of SQUALUS from all entanglements remaining from the
first unsuccessful lift.
E-12
Salvage of USS SQUALUS E.
All pontoons, hoses, and slings were removed since the
pontoon arrangement which had been in use was not suitable
for the final lift. For this final lift and tow into
drydock, the pontoons were rigged with the axis fore and
aft in line with the submarine.
A preliminary blow of the after compartments revealed
that they would not hold air pressure above ambient sea
pressure. Suction hoses were then attached to the low
salvage connections on these compartments and an air
pressure applied to equalize with sea pressure. The
salvage pumps on FALCON then pumped the compartments.
UJater which had accumulated in the control room and for¬
ward battery room was also pumped out through the low
salvage air connections in these compartments. Two slings
were placed under the stern and two pontoons were set
parallel to the axis of the submarine (Figure E-6).
Unsuccessful Attempt at Final Lift
E,14. 27 August 1959
The first attempt to bring SQUALUS up with pontoons rigged
only at the stern was unsuccessful. To save time, only
the stern pontoons were used since it had been calculated
that adequate buoyancy could be restored in the forward
compartments and tanks. The lift was planned so that the
bow would be raised first because, with the stern on the
surface, air would spill from the forward ballast tanks
before they were completely blown. As the bow of SQUALUS
came up, it was noted that she was statically unstable.
The submarine rolled to port, thus losing considerable air,
causing the ballast tanks to reflood. The submarine sank,
landing on the bottom with a large port list. Gages had
been rigged to the port and starboard ballast tanks so that
the Salvage Officer could determine the submarine's list.
By flooding and blowing the ballast tanks, the submarine
was righted.
On the next attempt, the stern was brought up first, but
the angle was too steep and not enough air could be put
into the forward ballast tanks to start the bow up.
The stern was reflooded and allowed to settle on the
bottom. Then two pontoons were rigged forward with their
axes parallel to the submarine (see Figure E-6).
E ♦ 15 . Additional Preparations
^ The setting of the two bow pontoons was delayed due to bad
weather. Two of FALCON ' s moorings had broken their anchors
and these were replaced during this period.
E-13
Salvage of USS SQUALUS E.
Rough weather also made one of the stern pontoons wash
against the after torpedo room hatch. The pontoon hit the
handwheel and caused the hatch to open, subsequently
damaging the open hatch.
E.16, Successful Final Lift - 12 September 1939
After the hatch had been replaced and the additional
pontoons set, the final lift was again attempted. The
blowing sequence was from aft forward. While fuel oil tank
No. 2 was being blown, the stern rose a short distance and
then sank. This was due to spillage of air and partial
reflooding of No. 3 main ballast tank. The remaining
bubble was left in No. 3 main ballast, and while blowing of
the fuel oil tanks was continued, the stern rose to the
surface. The bow pontoons were blown, then No. 1 and No.
2 main ballast tanks. The bow rose after a small amount
of water had been blown from No. 2 main ballast tank.
The augmented buoyancy due to the expansion of air in the
tank was enough to unload the forward pontoons and the
ship again became statically unstable. The SQUALUS assumed
a list to starboard, spilled air from her ballast tanks, thus
causing the stern to sink.
The bow was lowered to the bottom and the list was again
removed. Next the stern was raised as before. No. 1
main ballast tank was left full so that No. 2 would be
nearly empty when the bow started up and the gain in
buoyancy as the bow rose would be decreased. The bow
started up with No. 2 main ballast tank almost empty;
the pontoons remained well loaded and provided the desired
righting moment, and the ship remained upright on the
surface.
It is interesting to note that such a simple thing as a
change in the sequence in which tanks were blown could
change an unsuccessful attempt into a successful lift.
E . 17, The Docking
The strong tidal currents around Henderson's Point made it
necessary to arrive at the Navy Yard within a short time
before or after slack tide.
The time consumed by the sinking and second raising of the
submarine made it too late to reach the Navy Yard at high
tide. Therefore, the speed was adjusted to reach the Navy
Yard at low slack water.
E -14
Salvage of USS SQUALUS E.
The draft of SQUALUS was 40 feet, as planned, so there
would be no serious trouble in case the ship were caught
in a falling tide. The depth of the channel at mean low
water was also 40 feet. Although SQUALUS touched the
bottom several times during this tow, no damage was
inflicted and she was freed each time without delay.
Upon arrival at the Wavy Yard, SQUALUS was placed beneath
the 100-ton sheer leg crane and a wire strap was attached
to the periscope fairwater. This held the submarine in an
upright position as she was pumped out. The forward deck
was raised above the water by blowing all tanks. The for¬
ward pontoons then were removed and the forward hatch was
opened and all compartments were dewatered. This brought
the submarine to a draft shallow enough to permit docking.
E -15