Page 41 - statbility for masters and mates

or
Ans. Draft 0:484 m
pr2
0:137 m
22 0:3 0:3 7
0:484 m
Volume of water displaced (V) pr2 d d V
Laws of ¯otation 29
Homogeneous logs of rectangular section
The draft at which a rectangular homogeneous log will ¯oat may be found as follows:
Mass of log Volume density
L B D SG of log 1000 kg
Mass of water displaced Volume density
L B d SG of water 1000 kg
But Mass of water displaced Mass of log
; L B d SG of water 1000 L B D SG of log 1000
or
d SG of water D SG of log
Draft SG of log or relative density of log Depth SG of water relative density of water
Example 4
b2
If BM is equal to 12 d determine if this log will ¯oat with two of its sides
parallel to the waterline.
Note. The centre of gravity of a homogeneous log is at its geometrical centre. See Figure 4.7
Find the distance between the centres of gravity and buoyancy of a rectangular log 1.2 m wide, 0.6 m deep, and of relative density 0.8 when ¯oating in fresh water with two of its sides parallel to the waterline.
Draft Relative density of log Depth Relative density of water
Draft 0:6 0:8 1
9 Draft 0:48 m >=
KB 0:24 m > see Figure 4.8 KG 0:30m;
Ans. BG 0:06m