C L DUBEY – EXERCISE – 09 (GROUNDING) |
Miscelleneous

# C L DUBEY – EXERCISE – 09 (GROUNDING)

###### Solution –
• Draft before Grounding = 6.70m, Aft = 8.86m

Trim = 2.16m
Correction to aft draft = 2.16 ⨯ 71/142
= 1.08m
∴ Hydrostatic draft = 7.78m

Draft after grounding = 5.90 m fwd

Trim = 3.4m
Correction to aft draft =   3.4 ⨯ 71/142
∴ Hydrostatic draft = 7.60m
Rise = P/ TPC ⨯ 100
P = (0.18 ⨯ 23.4 ⨯ 100)

= 421.2 tonnes

• Trim before grounding = 2.16m,

Trim after grounding = 3.40m
Change in trim = 1.24m
1.24 = 421.2 ⨯ d/192 ⨯ 100
d = 56.52 m from COF

From AP distance = 71.00 + 56.52 = 127.52m

• GG1 = (P ⨯ KM)/W

= 421.2 ⨯ 8.24/16130
= 0.215m

New GM = 0.765m

FSC = 1372/(16130 – 421.2)
= 0.0873m

GM (fluid) = 0.678m

• Rise of tide required = P/ TPC + P ⨯ d/ MCTC ⨯ d/ LBP

= 421.2/23.4 + 421.2 ⨯ 56.52 ⨯ 56.52/192 ⨯ 142
= 18 + 49.35

= 67.35cm

###### Solution –

Distance of grounding point from COF = 55m
We have P = trim ⨯ MCTC/d
Change in draft = P/TPC + P ⨯ d/MCTC ⨯ d/LBP
So, 80 =   P/18 + P ⨯ 55/130 ⨯ 55/140

Or, P = 360.74

GG1 = (P ⨯ KM)/ W
= 0.125m

Virtual GM   = GM – Virtual loss of GM( GG1)
= 0.475m

Also,
Trim caused = Tc = (P ⨯ d)/ MCTC ⨯ 100
= 1.526m

Ta = 0.796m,
Tf = 0.730m

Rise = P/ TPC ⨯ 100
= 0.200 tonnes

 Fwd Aft Draft 5.23m 5.74m Rise -0.200m -.200m -0.730m +0.796m 4.300m 6.336m
###### Solution –
• For vessel to unstable GM should be zero.

GG1 = 0.4m
So,
0.4 = P ⨯ 6.4/ 7200
P = 450 tonnes

We can calculate fall in tide –
Fall in tide = P/ TPC + ( P x AL / MCTC) + AL/ LBP
= 450/16 + 450 ⨯ 48/110 ⨯ 48/120
= 1.067m

• Trim caused = 450 ⨯ 48/110 ⨯ 100 = 1.964m

Ta = 1.014,
Tf =   ( Tc – Ta)
= 0.95m

Rise = 450/1600
= 0.281m

 Fwd Aft Draft 4.200m 5.100m -0.281m -0.281m 3.919m 4.819m -0.950m +1.014m 2.969m 5.833m
###### Solution –

We can calculate fall in tide –

Fall in tide = P/ TPC + ( P x AL / MCTC) + AL/ LBP
80 =    P/15 + P ⨯ 43/110 ⨯ 43/120
So, P = 386.95 cm.
GG1 = 386.95 ⨯ 6.4/ 6400
= 0.3869m

Residual GM = 0.91m

###### Solution –

We can calculate fall in tide –

Fall in tide = P/ TPC + ( P x AL / MCTC) + AL/ LBP
80 =P/15 + P ⨯ 58/130 ⨯ 58/140
P = 323.44 tonnes
GG1 = 0.346m
GM = 0.254m

Rise = P/ TPC ⨯ 100
= 0.202m

Trim caused = 323.44 ⨯ 58/130 ⨯ 100
= 144m

Ta = 0.701m,
Tf   =   ( Tc – Ta)
= 0.739m

 Fwd Aft Draft 4.15m 4.851m Rise -0.202m -0.202m +0.739m -0.701m 4.687m 3.948m
###### Solution –

Not possible to calculate displacement not given.

###### Solution –

W = 12200, distance from COF of grounding location = 61.5m

We can calculate fall in tide –

Fall in tide = P/ TPC + ( P x AL / MCTC) + AL/ LBP
100 = P/25 + P ⨯ 58/200 ⨯ 58/152
P = 608.21 tonnes.
GG1 = (P ⨯ KM)/W
GG1 = 0.404
Virtual GM = 0.495m.

Rise = P/ TPC ⨯ 100
Rise = 0.243m

TC = (P x D)/ MCTC
= (608.21x 58) /200
Tc = 1.870m,

We know that –
Ta = 0.972m,
Tf =   ( Tc – Ta)
= 0.898m

 Fwd Aft Draft 5.1m 5.2m -0.243m -0.243m -0.898m +0.972m 3.959m 5.929m
###### Solution –

Distance from COF = 78.44m
We can calculate fall in tide –

Fall in tide = P/ TPC + ( P x AL / MCTC) + AL/ LBP
80 =   P/36.9 + P ⨯ 78.44/378 ⨯ 78.44/180
P = 680.67 tonnes
GG1 = (P ⨯ KM)/W
= 0.381m
Virtual GM = 0.119m

Rise = P/ TPC ⨯ 100
Rise = 0.184m

TC = (P x D)/ MCTC
= (680.67 x 78.44) / 378
Tc = 1.412m,

We know that –
Ta = ( Tc x AL ) / LBP
= (1.412 x
Ta = 0.674m,

Tf = ( Tc – Ta)
=  0.737m

 Fwd Aft Draft 4.4m 4.7m -0.184m -0.184m -0.674m +0.737m 3.542m 5.253m
###### Solution –

Correction to aft draft = 0.75 ⨯ 75/150
= 0.375

Midship draft = 4.625
Fall in water at midship = (4.625 – 4.46)
= 0.165

16.5 = P/15 + P⨯ 75/120 ⨯75/150
P = 43.51 tonnes  