The following data are available from the hydrostatic curves of a vessel.
Draught(m): 4.9 5.2
KB(m): 2.49 2.61
KM(m): 10.73 10.79
I(m4): 65250 68860
Calculate the TPC at a draught of 5.05 m. (16)
Structured for DG Shipping MEO Class II examination scoring criteria.
TPC at a draught of 5.05 m from hydrostatic data.
Data: Draught 4.9 m: KB 2.49, KM 10.73, I 65250 m4. Draught 5.2 m: KB 2.61, KM 10.79, I 68860 m4.
BM = KM - KB. At 4.9 m: BM = 10.73 - 2.49 = 8.24 m. At 5.2 m: BM = 10.79 - 2.61 = 8.18 m.
Volume of displacement V = I/BM. At 4.9 m: V = 65250/8.24 = 7919 m3. At 5.2 m: V = 68860/8.18 = 8418 m3.
Displacement = V x 1.025. At 4.9 m: 8117 t. At 5.2 m: 8629 t.
The waterplane area between these draughts is the rate of change of volume with draught: A = (V2 - V1)/(draught change) = (8418 - 7919)/(5.2 - 4.9) = 499/0.3 = 1663 m2.
TPC = A x 1.025/100 = 1663 x 1.025/100 = 17.05 t/cm.
Answer: the TPC at a draught of 5.05 m is about 17.0 t/cm.