Page 205 - Introduction to Naval Architecture

RESISTANCE 191

Table 8.3 Coefficients for the ITTC 1957 model-ship correlation line

Reynolds ' number Q Reynolds' number Q

It) 5 0.008333 1C) 8 0.002085
5 X 1C) 5 0.005482 5 X 10 8 0.001671
10 6 0.004688 10 9 0.00153!
5 X ]<) 6 0.003397 5 X 10 9 0.001265
7 1()
II) 0.003000 10 0.001172
5 X ]() 7 0.002309 5 X 10'° 0.000991

Froude method
Using Froude's 'circular'or 'constant'notation:

A selection of O and/values are presented in Table 8.4. These apply to
a standard temperature of 15°C (59°F). The (c) f value is increased or
decreased by 4.3 per cent for every 10°C (2.4 per cent for every 10°F)
the temperature is below or above this value.
The two methods above represent two different philosophies for
scaling frictional resistance. Froude based his method on measure-
ments of the resistance of planks extrapolated to ship-like lengths.
Schoenherr and the ITTC used Reynolds' number as the basis for
scaling.