Stability – I : Chapter 7

  1. Ship of 2000t displacement of KG 3.66m , loads 1500t( KG5.5m ) 3500t (KG 4.60m ), and takes 1520t of bunkers (KG 0.60m ). She discharge 2000t cargo ( KG 2.44m ). and consume 900t of bunkers ( KG 0.40m ). Find the KG at the and of the voyage.
Solution :
Ship’s   weight
KG
VM
2000t 3.66m 7320tm
1500t(load) 5.5m (+)8250tm
3500t (load) 4.60m (+)16100tm
1520t ( load) 0.60m (+)912tm
2000t ( discharge) 2.44m (-) 4880tm
900t  (discharge) 0.40m (-)360tm

Final W   =   5620t                                                    Final VM  = 27342tm

We know that:-

Final KG =   (Final VM) / (Final W)
Final KG = (27342) / (5620)
= 4.865m

  1. A ship of 3200t displacement KG 6.2m , loads 5200t of cargo (KG 4.8 ). Find the amount of deck cargo (KG 10.2m ) that can be loaded so that the KG shall be 6.0m when loading is completed .
Solution:
Ship’s weight
KG
VM
3200t 6.2m 19840tm
(+) 5200t (load) 4.8m (+)24960 tm
(+) X t 10m (+) 10X tm

Final W  = (8400 + X )t                                     Final VM   =(44800 +10X);

We know that:-

Final KG =   (Final VM) / (Final W)
6 = (44800 + 10X )/( 8400 + X)
6 (8400 + X  )  = ( 44800 +10X)
(50400 + 6X ) = (10X + 44800)
( 10X – 6X) = (50400 – 44800)
4X = 5600
X  =  1400t

Hence , amount of deck cargo to be loaded to get  required KG is  1400 t

  1. A ship 0f 2600t displacement , KG 4.88m, loads of 4600 t of homogeneous cargo (KG 5.0m ). Find how much deck cargo (KG 10m ) may be loaded to obtain a final KG of 5.11m.
Solution:
Ship’s weight
KG
VM
2600t 4.88m 12688 tm
4600t (load) 5.0m 23000 tm
X t (load) 10m 10X tm

Final W   = (7200 + X) t                                              Final VM =(35688 + 10X) tm

We know that:-

Final KG =   (Final VM) / (Final W)
5.11  =  (35688 + 10X )/( 7200 + X )
5.11( 7200 + X) = (35688 + 10X)
(36792  + 5.11X )  = (35688 +10X)
(36792 – 35688) = (10X – 5.11X )
X  =  1104 / 4.89
X  =225.766t.

Hence amount of deck cargo added to get desired KG is 225.76 t.

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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