Staility – I : Chapter 2

7. A collision bulkhead is triangular shaped, having a breadth of 14m at the tank top and a height of 12m. As a result of a collision, the forepeak tank gets ruptured and SW enters the tank to a sounding of 9m. Calculate the thrust on the bulkhead.

Solution :

B = 14m, H =12m

As we know that :
Pressure = (depth x density)
Thrust   = (pressure x area)

An right angle triangle PBC , PB =7m
Since, Height divide AB  equally into two parts.
Triangle PBC  and   FEC are similar
So by law of similar angle triangle

PB/ FE = PC / FC
7 / FE  =12 / 9

Hence, FE  =  (63 / 12)
              = 5.25m

In triangle DEC
DF = FE
DE = (2 X FE)
       = 2X 5.25
       =10.5m

Area of triangle DEC = (1/2 x10.5×9)
                                    =47.25m²

Pressure = (depth x density)
                  = (9 x 1/3 x 1.025)
                 = 3.075 t/m²

Hence Thrust experienced  = (P X A)
                                            = (3.075 x 47.25)
                                            =145. 29 t