Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

separate explanation. The study of a barge tow is taken up first,
then the analysis of the waterway firm is discussed.
In his attempt to develop empirical representations of tow per-
formance, 1 Howe began with certain basic engineering relationships.
A barge flotilla must be pushed through the water by a towboat. The
resistance of the flotilla is a function of the speed at which the
flotilla is moving through the water; certain characteristics of the
flotilla (length, breadth, and draft); and certain characteristics of
the waterway (width and depth). On the other hand, the push generated
by the towboat is a function of certain characteristics of the boat
(horsepower and speed) and the depth of the waterway. (The width of
the waterWay wah not regarded by Howe to be an important factor in
determining a towboat's effective push.) In order for a tow to be
operating at a Constant speed through still water, flotilla resistance
must equal the effective push of the towboat. 2
Howe then estimated these functional relationships. In order to
estimate the resistance function, data were taken from tank tests of
barge flotillas, i.e., tests using small scale-model tows in large
water-filled teat tanks. According to Howe, naval design theory indi-
cates that the resistance function should take a log-linear form.
After trying many equations, he decided that the following gave the
best fit to his data:
' a /(U-H) 'a a +a /(W -B)
1
, a a
R =
2
a
3 4 5
e S H L B
6
,
, (2:1)
0
17