A. 1.05 feet
Incorrect.
B. 1.15 feet
Correct.
C. 1.25 feet
Incorrect.
D. 1.31 feet
Incorrect.
Step 1:
Calculate Mean Draft.
15'-05"fwd + 21'-03" aft = 36'08"
Mean Draft: 36'-08"/2
Mean Draft =
18'04"
Step 2:
Using the
Hydrostatic Properties
table (Sheet 3) for the SS American Mariner (White Pages),
calculate the Total Displacement (S.W. Tons) for the vessel before
loading bunkers with a mean draft of 18'04".
The table yields
12,000 tons as the
displacement of the vessel at 18'04" mean draft.
Step 3:
Add up all the bunker totals for each
tank. The sum of all bunkers equals
3024.8 tons.
Step 4:
Add the displacement of the vessel
before loading the bunkers and the sum of all the bunkers to find the
ship's final displacement.
12,000 tons + 3024.8 tons =
15024.8 tons
Step 5:
Refer to the
Table for Free Surface
Correction and Tank Capacities (Sheet 4) to calculate the
free surface moment for each tank. On the S.S. Mariner , a tank is
considered FULL if the tank is at least 97% full. Any quantity less
than 97% full or an empty tank is considered SLACK.
In the column
F.O. Tons under
Tank Capacity, the
table gives you the capacity of each tank at 97% full. This is the
column you will compare your loaded bunkers in each tank with to
verify if a tank is considered FULL or SLACK. For example, DB 1 CL is
loaded with 48.2 tons of bunkers. The tank capacity at 97% for D.B. 1
CL is 48.2 tons. Therefore, the tank is considered FULL and its free
surface correction is 67. Conversely, D.B. 4 CL is loaded with 208.6
tons of bunkers. The tank capacity at 97% for D.B. 4 CL is 224.1 tons.
Since 208.6 tons is less than 224.1 tons then D.B. 4 CL is considered
SLACK.
Now find the free surface moment for
each tank.
Next, find the total sum of free
surface moment which equals
17,309 foot tons.
Step 6:
Find the free surface correction in
feet by dividing the total free surface moment by the
final displacement of the vessel.
FS(corr) = 17,309 foot tons/15,024.8
tons
FS(corr) =
1.15 feet
