The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1892-11-01
LAUNCHING A " VESSEL
OLD TIME METHODS ARE ADAPTED
TO MODERN CONDITIONS.


Poised the Ways.
The launch of a modern vessel does not
differ materially from one of older DAYS
except in detail and enlarged RESPONSE
bility. it is now n question of nathemat-
les rather than of personal experience 1t
is now n matter of applied science and not
one of fortunate guesswork. The con
structor in these days does not fix the scale
of the inclined plane down which the YES
sci will glide by his experience in such
matters; does not smear the tallow Oh the
ways until it seems to be enough; does not
adjust the size of the ways to suit his
fancy. Vessels that cost from 81 900, 600 to
100000 are too valuable for the running
of large risks, and hence the equation. the
formula, the methods of applied mathe-
matics, have supplantcd old time ways of
trusting to individual Judgment and good
luck.
Three things are absolutely necessary in
launching n vessel in tidal waters-thc
launch must take place on time. must he
of moderate speed. and ali straining of tile
vessel must lie avoided. 1t is in this last
particular that the greatest responsibility
rests nowadays. y wooden vessel may be
subjected to 4 great strain, her seams may
open and. rs II naval constructor recently
put it, she may almost be stood on her
head" and yet escape serious damage in
launching. '.N::e seams will close again
and the timhers and planks adjust them
selves. Not so with iron OF steel vessels
If the plates are strained, the rivets bent
or broken. the injury is permanent and a
matter of the gravest Importance.
Preparations fer launch are begun be-
fore the keel is laid. The incline of the
plane has first to be figured out. 1t gen
orally varies from Onc-half inch to one inch
to the foot. Vessels OF large tonnage
have less inclination than smaller ones.
The City OF Paris had only oue-half an inch
inclination wien she was launched The
cruiser Columbia, so long known rs the
Pirate. and recently launched at Cramps
shipyard III Philadelphia, glided into the
water at an inclination of thirteen-six-
tecnths of an inch to the foot. She went
down the ways like n race horse. Mir Nixon.
the constructing engineer of the Cramps.
planned to have her in the water in thirty
seconds after size started She made it in
twenty-nine. More vessels are launched
at an inclination of threc-quarters of an
inch to the foot, however, than at any other
plane.
The ways, rs is generally known, con-
slst of two parts the ways proper and the
cradle. The ways proper are stationary
and firmly fastened to the ground. The
cradle rests on top of the ways and up
with the ship. Between the WAYS proper
and the cradle the tallow is smearcd. This
is generally spread five-cighths of an inch
thick and must be of the highest grade.
That used by the Cramps is made in Phil.
adelpnHi and costs from seven to EIGHT
cents pound About II 600 pounds was
used III the launching of the Pirate. 1t is
heated in biz kettles in the shipyard and
spread en- Ivy hand. In the case of the
IlriIte the weather was so warm that there
was serious danger that the tallow World
melt and run away Mr. Nixon therefore
mixed 10 per cent stearine with it, He
also played u hose on the tallow and went
SO Tar rs 70 sit up nights with the mixture
to watch the effect of the weather on il.
The stearine hardened the tallow and the
launch was successful.
Perhaps tie most important element 10
be considered in the launch of today is the
Duoyancy a. the water and its effect on
that part Of he vessel which IS still on tbr
stocks after probably onc-half of the.vessel
- III the water Recently one of the new
English bat'eships of the Il, 000-ton class
was wrecked at Ecr launch. The buoyanoy
OF the water lifted her up at the heels and
threw her immense weight forward on her
shoulders, crushing the frames and the
l&unching ways, and running the boat.
The modern naval constructor reduces this
question OF buoyancy To Il matter of mathc
ilatics at once. He starts with the CUES
t!on OF specific gravity of the vessel. Ii
there were nc water for the shin to slid,
Into she would continue in the line of the
ways until the center of gravity would rct
over the end of the ways, and then She
would tllt. Bat the water keeps her from
dropping down and holds the vessel in ,hn
line of the ways. This water is the safety
waive OF the launch, but it must not be too
safe. While the moment of buovanoy
must always be greater than the moment
OF weight, it must not be so much greater
as to throw a terrible pressure on the for
ward end OF the vessel and wreck it.
Having arranged all these things. day
and an honr are set for the launch, the
time OF the high tide being the chief factor
to be considered. Most of the props are
taken down and the vessel rests on the Keel
BLOCKS AMI one or two sets of stocks ut Tho
SIDES. The ways and cradle have been fixed
IN place, and wedges have been adiustad
above the cradle and under the poppet
blocks on which she rests A batterin.,
ram consists Of four men 10 II piece of stout
timber. These four men take care of four
wedges. The sigma! is given and an i'm
mcnsc clatter begins as the men drive
home the wedges for five minutes. The
vessel is lifted just clear of the keel blocks
ana now rests on the ways. Alternate keel
blocks are now knocked away, beginning
at the stern. Another wed ging upn fol-
lows, and then all the props at the sides
are removed
After rest the third wedging comes,
and then all the keel blocks are knocked
down, the word is given, and the planks
that hold the cradle to the ways proper at
the bow are sawed off, and the vessel starts
down to the water. This is the supreme
moment i'll the shipbuider's career. In
thirty seconds all the responsibility of his