The Olneyville times. (Olneyville [Providence, R.I.]) 1887-1917, 1915-01-08
GREAT DRYDocKS.
Whare the Largest Warships Can
Be Repaired In Safety.
HUGE BASINS OF CONCRETE.
into These the Vessels Are Floated and
Shored Up as the Gates Are Closed
and the Water Pumped Out-Float ng
Docks and How They Are Used.


anti-fouling composition. and probably
there never will be.
BY "anti-fouing" we mean a solu
ton which. applied TO the bottom o.
ship. will keep her clean for an indeh-
mite period.
True, vessels can now keep the sea
for months on end without getting foul
enough to seriously diminish their
speed. but In the long run their bot
toms become weed grown, and they
are obliged to go into drydock and be
scraped and cleaned and repainted.
In old days. when warships were no
larger than the steam launches which
now hang on Dreadnought's davits,
the seamen did this work themselves.
They ran the galley on to some con
venient beach. hauled her out, tipped
her on one side on the sand. scraped
her and caulked her seams
Even In the eighteenth century Cap
tain Cook "careened' his vessel In
tidal creek on the Australian coast and
did necessary repairs. The enormous
warships Of today require very differ
ent handling. and ii is for their Use
that dockyards are fitted with dry"
or Craving" docks OF vast dimen.
sions.
A drydock is huge basin excavated
I'm the ground 1t is lined first with
this in turn is coated with thousands
OF tons Of concrete.
The first great requisite of dry
dock is to be dry, and as 1t is always
cut in low. swampy ground, with the
bottom far below low tide mark. this
is the great difficulty before its bui d
ers.
The bottom is quite flat The sioes
run up In steps-enormous steps, each
about yard high, not the sort of stair
case TO run down in n hurry,
These steps are known as "altarS,"
and they have two separate purposes
first for supporting the workmen's
scalfolds, the second and more impor-
tant for the fixing of the Shores"
Shores are the great balks Of timler
A drydock does not usually open
straight out of the sea or harbor Mere
often there is wet dock between.
The reasons are that vessel can tn en
be docked at any state of the tide Id
also that there is less pressure on the
great watertlght gates of the drydocl-
The actual process of docking in dry.
dock is simple enough. The drydock
is filled with water, the ship is float,i
in. the gates close behind her; then the
water is pumped out by means Of pow
erful steam pumps.
Along the bottom of the dock runs In
a straight line row of keel blocks On
which the keel Of the vessel rests. AS
the water is pumped away an army Of
workmen fix the shores i'm position.
This is a task which requires great
care. Not SO very long ago an 5000 ton
cruiser which was being drydocked 1T
one Of the southern dockyards in Eng.
land was so carelessly shored up that
she slipped and toppled over.
The damage was appalling. The huh
many thousands of pounds to repair
her
There are also floating craving docks
There is one at Portsmouth with an
area of two and one-quarter acres ard
lifting capacity Of $1,000 tons 1t Is
700 feet long and l1I feet wide Its
cost was f26i000
The beauty of n floating dock is that
If vessel is badly damaged the dock
can go TO the ship instead of the sh p
TO the dock. Also even If the ship is
heellng over 20 that she could not be
passed through the gates of store
dock. the floating dock can take her
The floating dock is simply a large
cradle built in series of watertiglt
compartments which can be filed or
emptied ut will Ii was invented by
George Rennie in 1896 BY means Of
a floating dock large warship can he
raised high and dry within three hours
Aboard, life goes OH as usual, while
the sailors floating home stands shored
up In dry dock Her decks are just
about level with the top of the sides,
but between them and firm ground
yawns chasm at least forty feet deep
During wartime the work Of clean
ing and repainting the under part of
the hull goes ON night and day, and
Job that usually takes n fortnight may
De completed within four 'or even three
lays.-Pearson's Weekly