The given values from the problem are:
Length = 13 meters
Diameter = 1.5 meters
Capacity = 70 %
Water density = 62.4 lb/ft3.
Equation: ((3.14(39.375/12)**2)x13x39.375/12) x .60 x 62.4 = X
Where X will be the load in pounds. You just have to use your calculator to calculate the value of x given the equation.
Hope that helps you.