From the archive, originally posted by: [ spectre ]  

from The Navy’s Safety Center

Photo of the Week
Some People Sure Are Trusting

“OK, this wasn’t in America. I sometimes think I’d put our
knuckleheads up against anybody’s, but maybe not. If they had an
Olympics for flagrant hazards, we’d be out of the medals if this is
the competition.

On the plus side, he is wearing a hard hat. Also, if you look carefully
at the boulder’s 4 o’clock, you’ll see a plastic drink bottle
propped on another rock, so he is also staying hydrated. And maybe that
boulder is actually 20 feet long, so that’s just the tip sticking
out. Yeah, that’s it.

We appropriated this item from our kindred spirits at Safety Soapbox,
home of the excellent and always startling “Absolute Shocker of the
Week” and “Bodgey Scaffold of the Week.” The Safety Soapbox is an
initiative of WorkSafe Victoria, which is a division of the Victorian
WorkCover Authority, a branch of the Australian government.”










“Don’t Panic, or You Will Die”

by BMC(SW/DV) Michael Hardgraves

It happened while I was stationed at the Consolidated Divers Unit (CDU)
in San Diego. I was on a dive team tasked with installing a shaft wrap
on a carrier, undergoing upkeep in Alameda, Calif.

A shaft wrap is designed to create a temporary seal around the
propeller shaft from outside the ship so the permanent seal can be
worked on from inside. A stern tube surrounds the shaft where it exits
the hull to prevent waterborne debris from being sucked inside and
damaging the seals.

Just another maintenance dive, right? And you probably think diving to
40 feet on surface-supplied air (with a Jack Browne) is easy. When what
I’m about to describe happened, I was 40 feet below the surface, under
an aircraft carrier, with zero visibility, and my dive rig knocked
sideways on my face. I was choking on cold water, almost lost my
self-control, and teetered on what I thought was the edge of imminent

Our dive plan included sending a 10-person dive team headed by a master
diver and using the Fly Away Dive System One (FADS I) as our air
source. The MK 1 band-mask was our primary dive rig. We also took the
Jack Browne (you can guess how old I am), should we have to perform any
enclosed-space diving, and a scuba bottle and regulator as the
secondary air source for the diver going into the space.

Sealing a shaft includes using wooden plugs to plug all stern-tube
deadlights (holes) from the outside and filling the two-inch gap-where
the shaft exits the shaft end of the tube-with a homemade gasket.
Divers aptly have named this gasket a “weenie.” It is a piece of
Samson-braid line, cut to length and wrapped in cheesecloth, which has
been soaked in a brew of bees’ wax, paraffin, vegetable oil, and resin.
Once temporary seals are in place, suction is taken on the stern tube
by rigging an eductor through a deadlight or through the gap between
the shaft and the stern tube.

Water simultaneously is drained from the permanent seals inside the
ship into the shaft-alley bilges. Sound-powered phones rigged between
shaft alley and the dive station are used to communicate with the dive
supervisor to inform him when the seals have stopped draining. During
the wait, divers swim the length of the stern tube (more than 200
feet), to check for leaks in the free-flood area. They conduct the
checks by feeling for water flow through seams and holes; the process
is time-consuming, to say the least.

An alternative is to enter the stern tube and wrap the shaft directly
at its hull penetration, but this method also has its own problems. You
have to unbolt an access cover that’s been underwater for months, work
in a confined space with limited visibility, and-most importantly-have
a restricted egress point. While the greatest danger during any dive is
loss of air supply, the possibility of entrapment multiplies the danger

The Jack Browne enclosed-space diving rig used for this dive consisted
of a small, triangular-shaped, full-face mask, with an air valve on its
right side and a spider-strap to keep the mask firmly on the head.
However, with this high-speed, low-drag configuration, divers
sacrificed communications. There was no way to talk with topside except
through line-pull signals sent as a series of jerks on the air
umbilical. Of course, when you’re inside an enclosed space, these
signals somehow never make it topside, so it becomes standard operating
procedure for your dive buddy to tend your umbilical from outside the
space and talk to topside for you.

When we arrived on station, the ship was moored starboard side to a
pier that was an ant’s nest of commotion as people, forklifts and
cranes moved at a typically frenzied, shipyard pace. Moored as such
placed the ship’s No. 2 shaft (the shaft on which we were working)
outboard from the pier. The best spot to set up the dive station was on
the pier, which meant we had to swim past shafts 1 and 3 to reach our
worksite. After locating our ship’s liaison, the dive-safety sheet was
routed, and the divers’ danger tags were hung.

Diving operations began about noon on the first day, and, from the
start, we realized this job would be difficult. Everything about diving
around a CVN is magnified. Just to reach No. 2 shaft, in this case,
meant descending to 40 feet, then navigating past the two starboard
shafts and crossing the ship’s centerline, a distance of about 200 feet
from the pier. To make matters worse, pieces of line dangled from hull
fittings along most of the route; these lines threatened to foul us as
we swam to and from the worksite. We had decided to seal the shaft by
plugging the stern-tube holes from the outside, but every ship is
different, and, since there is no set amount of holes or seams to seal,
finding all the deadlights in the stern tube proved to be a monumental
task. We finally secured diving operations at 2100 without getting a

The team arrived on station at 0600 the next day and splashed the first
divers at 0700. Each group was good only for about three hours in the
water, due to decompression considerations and water temperature. The
second day evolved into evening-still with no joy-as water continued to
drain into the shaft-alley bilge at the same rate. Finally, at about
2000, we decided to enter the stern tube to seal the shaft, so we broke
out the Jack Browne rig.

This particular dive began about 2100. Water temperature was 55
degrees, and visibility was three feet. I was the enclosed-space diver,
so I carried the scuba tank and regulator, while my dive buddy, who
would tend my umbilical from outside the space, was in a MK 1 mask.

As we swam to the worksite, he was about 15 feet ahead, but all I could
see of him was his dive light. Although we didn’t realize it at the
time, we had taken different routes. Apparently he swam over both
starboard shafts, while I swam underneath them. When we arrived at the
worksite, I entered the stern tube and placed the scuba cylinder on a
steel support; meanwhile, my buddy tended me from outside. The upper
third of the shaft was in an air pocket, and going from water to air
made it difficult to see the seal opening. Holding my dive-light in one
hand, I had to squeeze my body between the shaft and the surrounding
bulkhead as I shoved the weenie into the gap. Eventually, I had it in
place and thought I had a good seal, so I gave three tugs on my
umbilical. My buddy took up my slack as I worked my way out of the
space. I passed him the tools and scuba tank and squared away the
worksite; he signaled by holding up four fingers that he was ready to
surface. I returned his four, and we swam for home.

As we crossed the ship’s centerline, a piece of line snagged one of my
fins, and I paused to clear it as my buddy swam on. Looking up, I could
see his light in the distant blackness, and I caught him just in time
for us both to pass under the No. 3 shaft. As we swam, a growing
tension on our umbilicals pulled us closer together until we couldn’t
go any farther. My head was stuck at his weight belt, with less than an
arm’s length between us. In our dark swim from the worksite, he had
gone under the shafts when he should have gone over, and, when I
stopped to clear my fin, our umbilicals must have crossed and ended up
in a knot.

After five minutes of twisting and turning, I began to get frustrated
with the lack of distance between us and our inability to talk. He must
have felt the same way because we started to struggle against each
other, and he accidentally elbowed my mask sideways on my face. As luck
would have it, I just had exhaled and suddenly found myself sucking in
a mouth full of water! As I wrenched the mask back into place and
cranked up the air full blast, I was on the edge of panic.

Trying to catch my breath, I screamed at myself, “Don’t you panic, or
you will die!”  I was 40 feet underwater, under an aircraft carrier’s
centerline, and would have to swim 100 feet to clear the hull. At the
same time, my dive buddy realized what he’d done and started to
frantically grope my head and trying to put my mask back on. This
almost pushed me over the edge.

I knew if I panicked I would head straight up, even though there was a
large ship between me and the surface. To gain control, I grabbed his
arm and gave it one hard squeeze. A one means stop, which he did. I
took several deep breaths and told myself, over and over, that I was
OK. Once I calmed down, I remembered we had a scuba jug with us, but my
buddy was holding it. I promptly took it from him and told myself that,
no matter what else happened, I had something to breathe and could make
it to the surface.

Our main problem, because of our fouled umbilicals, was we were so
close together. We blindly tried to untangle ourselves, and he kept
bumping into me; I knew it was just a matter of time before he knocked
my mask completely off my head. The only solution I could come up with
was to unhook the spinnaker shackle from my dive harness, which would
give another two feet between us and, hopefully, would let my mask stay
in place. The problem with disconnecting the shackle is that it’s
designed as the pull point between the umbilical and the divers
harness; it’s ultimately the only thing linking the diver to topside,
and, if it’s jerked hard enough when it’s disconnected, the diver may
lose his dive rig-his only link to the surface. Such a consideration is
important, especially when you’re under an aircraft carrier at night. I
knew this, but I also knew my panic level was very high, and I didn’t
want to risk another breath of saltwater. Besides, I had the scuba tank
and could follow the hull to the surface if the worst happened. So, I
tightly gripped my umbilical below the mask to keep it from being
pulled off my head and unhooked the shackle. Suddenly we had plenty of
elbow room. My buddy then led me over to the No. 3 shaft and we sat
down on it to wait.

We spent the next hour sitting on the shaft, with me asking my buddy-by
squeezing his arm four times-if we could go to the surface. He
responded by giving me a single return squeeze, meaning I should sit
tight. Experience told me the standby diver had been splashed and was
in the water, looking for a way how to best untangle us. Time passes
slowly in a situation like ours, and, as I sat there, shivering in the
black, I wished I could talk with someone to help me forget the cold.

My buddy eventually gave me one more squeeze, and he swam off. I
figured topside had told him to move out first, meaning the standby
diver was doing his job, but I suddenly felt lonely. I now was by
myself, having no one to even squeeze. I reattached my spinnaker and
waited for the standby diver to get me. I was about ready to “lose it”
when-finally-I felt a pull on my umbilical. As I swam toward the
surface, I realized just how twisted a path my buddy and I must have
taken to get to the worksite. Following the strain, I went over, under
and around shafts and struts until the lights on the pier eventually
came in sight.

I never was so glad to get out of the water! The guys topside said my
eyes were like saucers when I surfaced. The cold that night had soaked
me to my bone marrow, and I didn’t stop shivering until I had had a hot
shower and had climbed into a warm bed for a good night’s sleep.

The next morning, we arrived on station, only to find that, despite the
previous day’s work and adventure, the shaft still leaked. We
eventually found half a dozen deadlights about 250 feet forward and
finally got a seal on the third day.

During my 20 years as a Navy diver, this dive was, by far, the
scariest. I attribute my surviving to tell you this story to superior
dive-school training, and to the master diver and my fellow divers who
were on station that harrowing night.

If any of your shipmates out in the fleet have stories similar to this,
or something you think might be of interest to the diving and salvage
community, submit your article to: SAFE-Divesalvage [at] navy [dot] mil-Ed.

“This is an official U.S. Navy Web Site”