Elmore bulletin. [volume] (Rocky Bar, Idaho) 1889-1906, 1893-12-30
IRON AND WOOD SHIPS
MATERIALS USED IN ssIIPHuIL DING
AND THEIR VALUE.

The Points In which Iron and steel Are
Superior to wood-Their Lightssss
and Durability and tho Comparative
Safety Of All Kinds Of vesseis
The three materials used Ia the con
struction Of ships In general arc wood
iron and steel Wood has been In use
from time immemorial Iron Ii only
about fifty years old, and steel Ia easily
within the memory Of every man OF
moderate years. The importance Of the
three materials are inverseiy as stated
steel being the most valuable, then iron
and last wood Eoticeably Is this 90 In
the construction OF swift steamships
for wood 10 unsuited TO the great engine
power nowadays put into ships; II can
not properly stand the strain
Iron ships are superior to wooden ones
In the following particulars: Lightneas
combined with strength, durability when
properly treated. ease and cheapness OF
construction and repair and safety when
properly constructed and subdivided. In
wooden ships it has been found that
about one-half Of the total weight Of the
ship Is required for the hull. whereas IN
iron ships only from 30 to 40 per cent. OF
the weight Is thus taken up For in
stance, in n wooden armored warship
the weigh. OF the hull being 80 per cent
Of the displacement leaves 90 per cent.
for the weights 10 be carried In an iron
armored warship the weight OF the hull
Is only 20 per cent. leaving 90 per cent
for weights to be carried.
The tensile strength OF iron IL from
Il, 900 pounds to &C. 900 pounds per square
inch, and this strength can be secured
throughout all the metal used, 10 that
the material worked into the ship h uni
form and homogeneous These are quail
ties wanting In wood; the greatest care
cannot eliminate such weak spots "a are
due to the presence of knots. crossgrain
hidden defects, etc. Generally good
sound timber may be said to have n
strength to resist pulling apart ttensile
strength) Of about 10000 pounds
IRON FAR SUPERIOR TO WOOD
When in shipbuilding II comes To
fastening pieces together. as. for In
stance, In making ships keel or her
deck beams. the weakness caused by
soaring the pieces Of wood together be-
comes an element Of strength In riveting
the iron. No matter how II may be nee.
esssary to treat the pieces OF metal
whether by riveting or welding or by
angle irons. the iron stands far above
the wood in resistance to tensile strains
II is only when resisting strains Of com
preston that there Is a tendency Of iron
plates to buckle, and this Ia guarded
against by making the plates thicker
than Ia required for other strains or by
reinforcing them
Durability is quality Of iron that IL
not yet thoroughly determined. In gen
eral. wooden ship may be- said TO last
about fifteen years Some last longer
but there will be much patching and re.
newing to be done. The rules OF Lloyds
allow about fourteen years rs the aver
age durability Of the best built timber
vessels.
Iron Is not subject to the internal
sources OF decay to which wood Ia liable
Worms ard marine animals cannot in
jure 1t, nor will II rot from imperfect
ventilation Neither can the parts work
loose from the motion and straining OF
the ship. allowing water to get IN and
cause decay The danger to iron lies in
the rusting or eorrosion. especially IN
the under water parts--outside from the
sea water and inside from the bilge
water The only prevention is careful
watching. cleaning and painting and
even with all this supervision galvanic
action Ia likely to do some damage
Therefore the life OF an iron ship is linn
tied, and In the present state of knowl
edge Of the subject may be set down ~
approximately thirty years. for. though
ship will last longer, extensive repairs
will have TO be made that will cost con
siderable money
STEEL BETTER THAN IRON
1t Is also easier TO repair an iron ship
since the necessary shape can be turned
out at once The rapidity with which
an iron ship can be built counts for
much. In the present day the ease with
which iron is obtained and worked con
stitutes another element of cheapness
for the final cost today must amount to
nearly % per cent less, especially when
the time. preparation, saving of weigh,
and life OF the ship are considered
As 10 the safety OF ship when prop
erly constructed and subdiyided, It is
only necessary to say that when tie In
ternal space Of an iron ship IL sub
divided into many compartments by
longitudinal or transverse partitions
rising TO sufficient height, or by hori
Eontal platforms. or inner skin. and ali
such divisions are made water tight, then
that ship b safer than any wooden ship
would be against laundering for the
space required for these bulkheads can
not be found In timber built vessel.
The subject OF steel may be briefly dis
cussed by remembering that steel Is sim
ply superior kind Of iron, and by vir
tue Of its greater strength is Of lighter
weight. The strength of steel Is from
10000 to 100, 900 pounds per square inch
Steel Ia a. strong lengthwiss "a II is
broadwise. iron Is one-hfth stronger
iengthwise than II il broadwise The
elastic limit OF steel Ia about IS per
cent greater than that Of iron So steel
may be trusted with working loads
nearly eo per cent greater than the 9th
er material Lloyds estimate that by
building ships of steel there is saving
In weight over iron of about IS per cent
or, to put the same thing in another
way, steel ship Of tho same dimensions
Is an iron ship would have an increased
cargo capacity Gin weight) of some 10 OF
20 per cent.
In the matter of cost. steel IL more ex
DenaiVe at first bt1f the hest nrn.nf NJ 10