New Iberia enterprise and independent observer. (New Iberia, La.) 1902-1944, 1910-04-30
TESTING SHALLOW DRAFT
MODELS.

One of the items in the present
Rivers and Uarbors Bill provides
for the expenditure Of some $500
600 to build experimental types
Of boats for shallow rivers. These
boats are to be butt and tried out
by the Mississippi River Commis-
sion to stimulate The use of new
kinds Of river boats on the Miss
issippi.
No plan has yet been worked
out by the Commission which will
allow these boats TO be used in
actual service in the handling OF
ordinary FREE ght commodities and
TO be loaded and unloaded by
dock machinery and almost the
only thing which is to be accomp-
lishcd by this expenditure of a
half million dollars is to test
boats under service conditions and
try to decide what are their de-
fects.
This work has been accomp-
lished in much more through
and practical manner and at far
less expense by the Mississippi
Valley Transportation Company,
which has had its designs tried
out and approved by one of the
most scientific naval architects in
the world, ITO determine with
large models in the testing tank,
every feature which the Govern
ment will be able to determine
with the actual boats and many
things which it could only work
out in successive boats through
long and hard service.
The testing tank is a novelty
in American shallow river prac-
tice, but is extensively used
abroad. On an island in the
Spree River in Berlin, known as
Leck Island. there is an instiu-
ton owned by the Government for
experimenting with models and
carrying on general Study of
the resistance Of ships in the wa
ter. On this island is al long
handsome stone buildifS contain
ing a main tank $50 feet long
and several smaller tanks, which
can be filled with water, and the
main tank is so connected with
the river that the natural current
Of the river can be made to flow
through it so the exact conditions
Of up and down stream towing
can be duplicated. Spanning
these canals is a steel bridge on
wheels equipped with an electric
motor for testing the resistance
Of boats to different kinds of
channels. These little basins are
lined with earth to concave, con-
rex and sEoping shapes before the
water is run in; and the boat is
owed through them under given
by the electric ma
'hine. Not only the size and
ahape of the waves are observed.
,ut the towing resistance of the
,oat is measured by very deli
ate sca.e; so it is possible to com
,ute the exact power needed to
rive certain speed in a certain
hannel.
When the depth Of channel and
he conditions on which boat is
o work are known. model OF |
he boat to be studied is then made II
n paraffin and this model is
owed up stream and down
through canal shaped and modi-
led exactly in proportion to the
main stream: that is to say. the
hannel is as many times smaller
han the river as the model is
mailer than the boat.
In long series of experiments
he model is tested with many
ariations: The bow is filled out
v the addition Of paraffine. or
ut away; the slope Of it is chang
d and the stern is likewise modi-
led; relatively more or less pow
+ used. and the economy CON-
uted. In the end il is determ-
led inst what sort Of boat will
est suit the channel.