Page 191 - Introduction to Naval Architecture

RESISTANCE 177

In verbal debate ® and (g) are referred to as 'circular M' and 'circular
B' and so on.
To cover the ship's performance Froude introduced:

with subscripts to denote total, frictional or residuary resistance as
necessary.

Elements of form diagram
This diagram was used by Froude to present data from model resistance
tests. Resistance is plotted as © - ® curves, corrected to a standard 16ft
model. Separate curves are drawn for each ship condition used in the
tests. Superimposed on these are curves of skin friction correction
needed when passing from the 16ft model to geometrically similar
ships of varying length. The complete elements of form diagram
includes, in addition, the principal dimensions and form coefficients,
and non-dimensional plottings of the curve of areas, waterline and
midship section.
Although Froude's methods and notation are not used nowadays,
they are important because of the large volume of data existing in the
format.