The islander. [volume] (Friday Harbor, Wash.) 1891-1899, 1894-11-08
DOCTORING SHIPS
PARASITES THAT SEND oce.,
sells TO THE HosPlru '"

Been fonnd-Ihe Old and the New M
ners Of OBSERVATION-DISCLOSURES. 4,
Drydocks and Their Uses.
The sea is a grand and yet a tro,,,
GUS mother to the thousands Of ~.
that sail over its broad expanse, and -
er buffeting with its storms the "a a'
must go to their hospital for raDa;
This hospital is the drydock, and ~
doctors are the army of careful ~
men who look over carefully and , ~s
every faulty seam or broken rivet pau
Salt water is teeming with nar.s..
Of plant and animal life that cline
the bottoms of ships, eat SLOWLY ),
surely through wood and iron ally
rust it away, while they act as a choG
on the speed by vastly increasips ~
resistance and friction of the . pT, t4s
against the ship. The "gods Of W.
storms see everywhere" and pick ou '
each weak seam or faulty rivet sna
slowly and surely eat into the yitaIS =.
the ship, so that every few months !.
becomes necessary to examine and ~
pair the vessel. To do this she NV.
come out Of the water. The drydocI;,
just a great box of wood, iron and stona
connecting with the sea by great pat@
way. = When the ship is ready to enter
the gate is shut and the water all pumn
ed out; then the workmen, with nror
ticed skill, place the blocks at the hot
tom Of the dock for the keel to roc.
upon, taking the dimensions from tbo
plans and drawings of the vessel. Tbpso
in place, the dock is flooded again tba
gate opened, and the ship hauled in
The gate is now closed again, and wbiIa
the water is slowly pumped out and the
ship settles down the lockers pull bo,
this way or that until she rests eyenv
on the keel blocks. Then shores, q,
heavy wooden beams, are braced from
the sides of the dock to the sides of tho
ship, and as the water is pumped away
the ship stands "high and dry" yer.
liable ''flsh out Of water" the bottom,
which was below the water line, cover.
ed with seaweeds and parasites that
hide the defects they have caused.
Then the worlzmen scrape and scour
the unwelcome barnacles and Grass
away, the seams and rivets are all ex.
amined and repaired, a fresh coat Of
paint goes on again, and as the dock is
again flooded the ship rises from her
hospital bed, and the wooden supports
are knocked away until she floats out to
sea again, "healthy and strong" to
battle with the wind and sea and the
enemies Of the flag she proudly flies
When wood was used almost exclu.
sively in building ships, very easy and
convenient means was found to protect
the under water portions of the ship
from the insidiou5 attacks of barracks
and parasites Of plant and animal life
This was done by covering the whole
bottom of the ship with a plating Of
thin copper, for the galvanic action Of
the salt water upon the copper was to
convert the ship and sea into vast bat
terry, where the copper became the mega
tive pole and was slowly yet constantly
eaten away, the particles, as they fell,
taking with them the barnacles and sea-
weed as fast as they formed on the
ship, thus keeping the ships bottom
and sides always clean, so that the speed
was not cut down by dragging the bar
nacles and yards of seaweed through the
water. Yet even then the copper need
ed repairs; faulty timbers rotted and
crumbled away, so that every few years
the ship had to go into drydock and be
thoroughly overhauled, each faulty tim
Der replaced and rusty bolt repaired un-
til no loophole was left for the sea to
work upon.
But with the advent of iron in the
building Of ships the old means failed
for where copper was placed over iron
the iron became the negative pole of the
great battery and was eaten away quick
ly, riddling the bottom of the ship with
many leaks. Many devices were tried
the under water portions of the vessels
were covered with waterproof layerOf
wood, which was then coppered as be.
fore, but wherever there was any me-
tallic connection between the copper
and iron the whole force of the battery
acted there, and holes were eaten in IN,
expected and inaccessible places, bring
ing in an element of uncertainty and
enforcing great care in "sheathing" the
vessels, as the coating Of wood is called,
and the ships still had to go more often
than. ever to the drydock.
Then the various methods of painting
the bottoms with protective paints have
been tried and are used in all Of the
cruisers of our navy. The skill of hun
dreds of chemists has been exerted to
find paint that would act as the cop
per does and throw off the barnacles and
seaweed. Great prizes have been offer
ed, and fortune awaits the successful
discoverer of such coating for ships
yet so far none has been discovered thai
acts completely, and the iron and steel
ships which start from port with fresh
ly painted sides and bottoms return IN a
few months coated with barnacles and
sea weed, which, as it trails in the wa,
ter, very materially cuts down the speed
and power of the ship. Then she mus.
be put in the dry dock and scrubbed and
scraped and reprinted Still worse than
the barnacles and the seaweed is the
water itself when it finds an entrance,
be it ever SO small, through the PAM
to the steel below. Slowly but surely
1t rusts out a little pit, which extend'
sometimes almost through the plate BE-
fore the paint scale drops off and dis
closes the defect, which can even then
only be seen by putting the ship in Oh!
dock and examining every square foO'
of her bottom plating.
This all shows how necessary it isfor
the ships to go to their hospital anu