"Why is it so quiet?" I woke up asking myself. Not even the generators are
running! Very unusual!
Then I realized. My ship was in dry dock. This was the only time when the
generators were not running. Even while the ship was at anchorage or
alongside the wharf, the noise from the generators was ever present. But not
The dry dock is the repair or service yard for the ship. The whole ship is
brought to dry land so that the submerged portions of the hull can be
cleaned or inspected. This dry docking is done every 12 months to 24 months.
Of course, because there will be machinery and systems that cannot stop
while the ship is in use, these are also serviced, repaired or replaced at
the same time.
Large ships are brought in to a graving dock that consists of a large basin
with a gate that can be closed watertight. After the ship is positioned over
carefully arranged resting blocks, the water from the basin is pumped out.
As the water level drops, the ship gradually rests on the blocks. Wooden
wedges are then knocked in to take up any clearances between the hull of the
ship and the resting blocks.
In another arrangement, the whole basin can be floated and submerged at will
like a submarine. The basin is first submerged and the ship is brought into
position as before. Once the ship is in position, the basin is floated up,
bring the ship above the water level. This is called a floating dock.
Smaller ships have other arrangements like synchrolift that can lift up the
ship like a car in a garage. Once the ship is lifted up, there may be some
roller and track arrangements to transport the whole thing to a different
place in the shipyard. Slipways are also used when there is enough space. It
makes use of a sloping ramp where a small ship resting on a carriage can be
pull up using wire ropes.
For a routine dry-docking, the usual work to be done are:
Hull cleaned of marine growth. Painting with anti-corrosive and anti-fouling
paints. Sacrificial anodes renewed.
Hull inspection and repairs.
Shipside gratings cleaned and repaired. All overboard and sea suction valves
Cleaning and surveying of tanks.
Rudder, carrier ring, pintles, locking devices clearances examined.
Propeller damage, nut looseness, blade polishing done.
Tail shaft bearing wear down checked.
Tail shaft removed and inspected. Coupling bolts and holes deformation.
Anchor chain examined, cleaned and re-marked.
All underwater stuffing boxes repacked.
To the ship's personnel, this is a busy time. Although shipyard workers
will do a lot of work, many of the repair and servicing work will be
assigned to them. As with everybody working on the ship, this is a time to
be extra careful on safety. Many people are working in the same place at the
Some rigging workers are lifting heavy materials using chain blocks,
while some machinery workers are dismantling foundation bolts for the engine
below. Some welders are cutting pipes just a few feet away. Some workers
have removed floor plates so that they can crawl down to inspect the
cofferdam. Engine mechanics have dripped lubrication oil on the floor while
removing the main bearings. People on the next level are cleaning the boiler
tubes, and soot has spilled on the floor.
The whole ship, especially the engine room has become a mess.
For safety purposes, fire hoses connected to shore hydrants are laid on deck
and pressurized. Precautions are taken to avoid tools or other materials
from falling from the sides of the ship. Safety helmets are a must. Cables
or hoses do not obstruct excess to passageways. Fire extinguishers are made
available near welding sites. For long stay or cold climates, water in
engines or pipes has to be drained away to prevent freezing.
Some of the normal utilities may not be functional at that time. Often, the
seamen will have to use the shore shower and toilet facilities. If for any
reason cooling seawater is not supplied to the air-conditioning system on
board by hoses, then there will not be air-conditioning. Sometimes repair
work has to be done on the seawater piping. The boilers have been
dismantled, so there is no heating in the living quarters. Sometimes
shipping companies arrange special accommodation for their crew on shore
Dry-docking is not the normal routine work for the seafarer. There may be
some time to explore the land too. It could be fun!