The morning times., 1895-10-05
TO TEST SHIPS MODELS
Experimental Tank Proposed at
the Washington Navy Yard.
WOULD AVOID MANY ERRORS
Correct Lines for Speed and Details
of Displacement Could BE Obtain
ed-How These Points Are Worked
Out by the Naval Constructors of
the United States.

A subject that has engaged the attention
of naval experts for number of years, Is
the testing of naval vessels in advance OF
their construction. Experimental tanks,
as they are called, have been established
in almost every country in Europe, in which
the models of both war and commerce
ships are subjected to preliminary trials
as to their speed, stability, friction, and
turning qualities before the work of actual
construction is begun.
England, France, Germany and Italy
test their models in this manner, and these
experiments have been found TO be OF
great value.
The construction department OF the navy
of this country has been trying for several
years to secure the establishment OF such
an experimental tank at the Navy Yard
here where the models of warships could
hegiven a trial, tosettie OBSERVATION-DISCLOSURES
in connection with the construction.
Recommendation was first made by
Chief Constructor Wilson, who asked for
an appropriation of 100000 for that pur-
pose. Congress has SO far never been
induced, however, to consider the question.
Chief Constructor Philip Hichborn, how
ever, the successor to Constructor wilson,
has made deta lied reports to the head OF
the department, and the next Congress VIII
be asked for an appropriation of Sloo,ooo
for the purpose of building an experimental
tank at the Washington Navy Yard, IN the
sIip between the old shiphouse and the main
branch of the Potomac.
COST OF THE TANK
In an interview with Chief Constructor
Hichborn, he said that the Bureau de-
sired to renew most earnestly previous
recommendations in relation Ia 'the es-
tabl ishment OF an experimental tank. =
lone of the greatest obstacles en-
co.ntcred by this Bureau in designing YES
scls," said that gentleman, lis the de-
termination of a reasonably exact speed
which can be obtaiUed with snip Oh
known displacement, horse power, and
underwater form. At present our only
data for such purposes is derived from
more or less inaccurate reports of the
performance of foreign vessels, and Is
necessarily very unsatisfactory.
THE Bureau in the past has not even
had the benefit of experience gained from
thorough and exhaustive speed trials OF
our own ships, eXigcncies OF the service
usually preventing a complete series OF
progressive speed trials, such as have
zen found of so much value in other
services. The lack of reliable data, which
can only be accurately obta med from these
two sources, has hampercd the Bureau
in its previous design work, and placed
il at a decided disadvantage in fixing
upon the approximate speed to be ex-
pected from any given design.
The commercial value ofanexperiment
tank" continued the chief constructor, has
been well demonstrated by the experience OF
private establishment on the Clyde,
which has had one in operation for ten years.
Aside from the scientific value of the in
formation derived, they claim that ii has
been the means of saving them thousands
of dollars by enabling them to determine ac-
curatcly the best form OF ship TO attain a
certain speed. the dimensions OF the ship
being determined by certain definite CON
siderations.
BEGAN IN ENGLAND.
Experiments to determine the resistance
of ships in advance OF construction by
towing models OF the proposed ships, were
commenced by the late DR.. William Froude,
in 1879. in a tank bIilt by him at Toruuay.
This tank was ESQ ft.'t long, &c feet wide,
and 10 feet deep, and in it experiments were
carried on for tie Adnl.sality, and IN con-
nection with the towing experiments OF
the Greyhound, certain laws and deductions
were established beyond question.
Since the death of Dr. Froude in 1879
the work has been carried on by his son,
R. E. Froude, and many useful and valuable
results have been obtained. The designs
of many proposed ships have been altered
after model trials, notably in the case of the
Polyphemus and the Medway class of gun
boats, the deductions being after~ard
verified by the performance OF the vessels.
In 1882 tank Of about tie same dimen-
sions, and with practically identical ap-
pliances, were constructed by Denny Bros,
of Dunbarton, in which many thousands
of experiments have been conducted with
both engineering and commercial sue
cess, the tank having enabled them, as
the case in point, to successfully construct
high speed vessel for the Belgian gov
ernment under conditions so rigid, that
under ordinary circumstances surety Of
fulfilling them would have been impos-
sible.
The establishment of an experimental
tank would not only benefit the naval
service, but would greatly promote the
shipbuilGing interests of the country at
large, by furnishing reliable information
as to the future performance of new types
Of commercial vessels, that would aid
American shipbuilders TO compete on more
equal terms with foreign yards in which
similar information is already available.
MADE A LARGE OUTLAY.
The British admiralty considered the
results obtained so valuable that in 1885
new tank was constructed at Haslar,
near Portsmouth, and the apparatus at
Toruuay was removed to that place, and
installed there with many improvements
and additions under the charge of Mr..
R. E. Froude.
The latest apparatus constructed is that
installed by the Russian government, at
st. Petersburg, in 1892. To duplicate
such plant, Including cost OF all appara-
tus and the necessary buildings, but ex-
elusive of ground, would cost about $685.
600.
The experiment may develop the fact
that the intended lines produce an abnor-
mally high resistance, or are in some other
way unsuitable in which case the model is
easily altered or a new one made, and the
ship saved from probable failure.
In conducting the experiments abso-
ment are required. The model is care
fully ballasted to the exact draft and
trim to correspond with the proposed