Staility – I : Chapter 2

  1. Find the thrust exprienced by a flat keel plate 10m x 2m when the draft is 8m in SW.

Solution :  Area of the flat keel plate = (10 x 2)
                                                  = 20m2
               Pressure = (depth x density)
                                           =    (8 x 1.025)
                                          =  8.2t /m2
              Thrust = (pressure x area)
                                       = 8.2 x 20 =164 t .

  1. A box-shaped vessel 150m x20m x 12m is floating in a dock of RD 1.010 at an even keel draft of 10m. Find the total water pressure experienced by the hull.

 Solution: The total water pressure exerted on the hull to the water =  (Thrust of keel plate which acting   horizontally + Thrust of forward and aft  which act vertically +Thrust of  port and stbd side which act vertically)
Thrust of Keel plate = (pressure x area)
Pressure = (depth x density)
              =10 x1.010 t/m2

Area = 150m x 20m = 3000m2
Thrust =(10 x1.010 x 3000) = 30, 300 t

Thrust of forward and Aft =(pressure x area)

Pressure = depth x density
            =( 5 x1.010)t/m2

Area =L X B
           =(20 x10)
           = 200m2

Thrust = (P x A)
              = (5×1.010 x200)
              = 1010t

Thrust acting both forward and aft = (1010 x2)
                                                               = 2020 t

Thrust of port and stbd  side = (pressure x area)

Pressure  =( depth x density)
                   =( 5×1.010)

Area = (L X B)
          = 150m x 10 = 1500m2

Thrust = ( P X A )
              = 5 x 1.010 x1500
              = 7575 t

Thrust acting on Both sides = 7575 x 2
                                                =15150 t

Hence , Total pressure on the hull = (30300 +2020 + 15150)
                                                  =47,470 tonnes.

About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.

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