Page 125 - Practical Design Ships and Floating Structures

According to reference and Is], m, for two-dimensional wedge is:

at the moment of bilge wetted: mW = ~b'[f(P)]* tan' P (2-10)
Pn
(b) m, with bilge wetted
m, with bilge wetted which doesn't take free surface into account has been obtained according to
Bobyleff s theory, while the one with consideration of free surface has not existed, it can be calculated
by the sum of m, and ~m,, where m, is added mass at the moment of bilge wetted and~m, is
additional one which can be get with reference of Bobyleffs theory.
when a two-dimensional wedge is moving in fluid with a velocity of 4, force acted on hull of unit
length is :
f" = B:(5I2b (2-11 1
L
B is a hction about deadrise ( B ) l9], according to momentum theorem, there is:
rn, =m, +Am, =pb21f(P)tanPr + B-b P2rl (2-12)
(---)
8 2 b 2
(c ) m, for random section shape
m, for random section shape before its bilge immersed is :
m
m, = (2-13)
2c, sin' T cos' T
-
CB is planing lift coefficient in calm water [''I, then:

The change of surface rising is rather small when immerging depth is large enough, so it can be
regarded as a constant, assume: <' = 4, then:
W = 9(J..)[s(y+ ICY,)' + y fm,d<'
(2-15)
tanT tan7
3.2.3 Solution of motion equations

From Eqn.2-15, Eqn.2-16 can be get:

(2-16)
.. .
This formula can be solved by numerical integration, then the changing value of y,y and y about t
is obtained finally.

3.3 Impact Load in Waves
WIG must operate on rough sea where the impact load is much bigger than the one on calm water.
Motion parameters such as trim angle, track angle and downward velocity will change randomly
because of random encountering waves, so lots of mathematics statistic must be done to predict impact
load accurately. From viewpoint of engineering usage, the biggest load is the impact load