STABILITY BASIC FORMULAS

SOME BASIC FORMULAS


Area of Waterplane = L x B x CW

…. L = Length of vessel

…. B = Breadth of vessel

...CW = Co-efficient of Waterplane


Volume of Displacement = L x B x d x CB

…. d = depth of vessel

….CB = Block co-efficient

Volume (V) = L x B x d


Displacement (W) = L x B x d x R.D

... R.D = Relative density of water


TRANSVERSE STABILITY

Rectangular Waterplanes

BM = I . where I = LB3

V 12

…. V = Volume of vessel


Depth of centre of buoyancy below water line:

= 1 ( d + V )

3 2 A

LONGITUDINAL STABILITY

a) Rectangular Waterplanes

IL = L3B and BML = IL .

12 V


b) Box Shapes

BML = L2

12d


LIST

GG1(Horizontal) = w x d

W

….d = distance moved horizontal

….w = weight

….W = Final Displacement


GG1(Vertical) = w x d

W

….d = distance moved vertical

….w = weight

….W = Final Displacement

TANq = GG1

GM

….GM = Metacentric height


TANq = Listing Moments

W x GM ….GM = Use Fluid GM

…. W = Final Displacement



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DRY DOCKING


P = trim x MCTC

l

...l = Distance of COF from where vessel touches blocks first

...P = Upward force acts on ship where block first touches


P = COT x MCTC

l …..In case of declivity of Dock


Virtual loss of GM = P x KM

W

Virtual loss of GM = P x KM

(W - P) if P - force is very small


After taking the blocks (F & A):

P = Change in TMD ( cms ) x TPC or

P = Reduction in water level x TPC

….TMD = True mean draft


Change in Draft (rise) (cms) = P …always subtract from draft

TPC


TMD = Draft Aft – ( LCF x Trim )

LBP

….subtract if vessel is by the stern

….add if vessel is by the head



DRY DOCKING

HYDROSTATIC TABLES AND

VESSEL ‘A’ TYPE PROBLEMS


Proceed as follows :


1. Find mean draft from the present given drafts.

2. From this mean draft, look in tables for LCF

3. Using that LCF, calculate TMD

4. From the TMD, look in tables and find

MCTC, LCF and DISPLACEMENT

5. Calculate now P-Force

6. For Displacement (W) at Critical Instant, find W-P

7. From this new (W), look in tables for KMT

8. Now find Virtual loss of GM and use new KMT but old Displacement (W)

9. Find now initial GM, using the new KMT

10. Apply Virtual loss of GM in it and find the

EFFECTIVE GM.


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FREE SURFACE EFFECT / MOMENT


FSE = l.b3.R.D

12W


FSM = l.b3.R.D

12

….R.D = Density of liquid in tank

FSE = FSM

W


Corrected FSM = Tabulated FSM x Actual R.D

Assumed R.D


New FSM = Original FSM x 1

n2


….n = number of tanks which are subdivided


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DYNAMICAL STABILITY


Dynamical Stability = W x Area under the curve


STATICAL STABILITY




Statical Stability = W x GZ


KN CURVES


GZ = KN – KG.SINq


INCLINING EXPERIMENT


GM = w x d x Length of Plumbline

W Deflection


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RIGHTING MOMENT



SMALL ANGLES OF HEEL (UPTO 10O HEEL):


GZ = GM x SINq


LARGE ANGLES OF HEEL (WALL SIDED FORMULA):


GZ = SINq ( GM + 1.BM.TAN2q )

2

WIND HEELING MOMENT:


Total Wind heeling moment = F.A.d

1000

GZ (at angle of heel) = F.A.d

1000W


….d = Distance of centre of buoyancy to centre of windage area

….F = Steady wind force of 48.5 kg/m2


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SIMPSON’S RULES


SIMPSON’S FIRST RULE:














Area = h x ( a + 4b + 2c + 4d + 2e + 4f + g )

3


Remember : 1 4 1



SIMPSON’S SECOND RULE:









1 3 3 1




h h h


Area = 3 x h x sum of products

8


Remember : 1 3 3 1


SIMPSON’S THIRD RULE:

5 8 –1





















h h


Area = h x ( 5a + 8b – c )

12


Remember : 5 8 –1


NB:

Divide the value of ‘ h (in degrees) ’ by ‘ 57.3 ’ while calculating the area.


NB:

In the 3rd rule of Simpson, we are only looking for a particular piece between the area i.e., from one co-ordinate to other and this is mainly used by surveyors for calculating sludge in bunker tank etc. Also for knowing the full area, we use Simpson’s first rule.


GM CONDITIONS


GM AT LOLL:


GM = 2(Initial GM)

COSq ….answer will be –ive but write +ive sign


WHEN GM IS NEGATIVE:



WHEN GM IS NIL:



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TURNING CIRCLE


TAN(Heel) = v2BG

gGMr

….v = velocity of ship(m/s)

….r = radius of turning circle

….g = Acceleration due to Gravity


(9.81 m/s)

….T = Period of Rolls (seconds)

….K = Radius of Gyration


….p = 3.142857143 (constant)

….I = Weight Moment of Inertia about

Rolling axis (tonne - metres2)

Hence we get,



Actual New Draft = [ Initial draft + B Tanq ] Cosq

2

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AIR DRAFT


CALCULATING LENGTH OF THE IMMAGINARY MAST

WHICH IS EXACTLY ABOVE THE ‘CF’:


Correction to Aft Mast


= Dist. of center mast from Aft Mast x Diff. of ht between masts

Dist. between the two masts


….subtract this value from the ht of Aft mast

or


Correction to Fwd Mast


= Dist. of center mast from Fwd Mast x Diff. of ht between masts

Dist. between the two masts


….add this value from the ht of Fwd mast


FOR FINDING DRAFT FWD AND AFT


Trim between masts = Trim of vessel

Distance between masts LBP


…..(from this, calculate ‘trim of vessel’ and proceed as follows)


Trim Effect Aft = la x Trim

L


Trim Effect Fwd = lf x Trim

L


GRAIN


Weight of Grain = Volume

S.F


Weight of H.M = Volumetric H.M

S.F


Approx. Angle of heel = Total H.M x 12o

Max.H.M


…. Max.H.M can be found in the Tables of Maximum permissible

Grain heeling moment against ‘W’ and KG


GG1 ( lo) = w x d

W

….w = weight of Grain liable to shift while rolling

….d = horizontal distance of Grain shift


lo = Total volumetric H.M (in m4)

S.F x W


l40 = GG1(lo) x 0.80 ….80% of lo (GG1)


NB:

If value for cargo is given for centroid then follow as normal

but if value given for ‘Kg’ of cargo then,


Multiply H.M value for fully filled compartment by 1.06 and

Multiply H.M value for partially filled compartment by 1.12


TRIM

HYDROSTATIC TABLES AND

VESSEL ‘A’ TYPE PROBLEMS


Proceed as follows :


1. Find mean draft from the present given drafts.

2. From this mean draft, look in tables for LCF

3. Using that LCF, calculate TMD

4. From the TMD, look in tables and find

MCTC, LCB and DISPLACEMENT

5. Calculate now INITIAL LCG

6. Now Calculate FINAL ‘W’ and FINAL LCG by MOMENTS

7. With this FINAL ‘W’, go in tables and look find TMD, LCB, LCF and MCTC

8. Calculate TRIM

9. After this calculate TRIM EFFECTS ( F & A )

10. Now apply this TRIM EFFECT to find FINAL DRAFTS.


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TRIM


Trimming Moment = w x d ( d = distance from COF )


Area of Waterplane = L x B x Cw


Volume of Displacement = L x B x D x CB


TPCsw = 1.025A

100


FWA = W .

40 TPC


DWA = FWA (1.025 – R.D)

0.025


MCTC = WGML

100L


TPCDW = R.D x TPCSW

1.025


MCTCDW = R.D x MCTCSW

1.025


Displacement(DW) = RD x Displacement(sw)

1.025


Sinkage (cms) = w .

TPC






COT = Trimming Moments

MCTC


COD Aft = la x COT

L


COD Fwd = COT – COD Aft


WHEN THE VESSEL IS EVEN KEEL

LCG = LCB


FOR A BOXED SHAPED VESSEL


BM = B2

12d


KB = draft

2


FOR A BOX SHAPED VESSEL WHEN DISPLACEMENT CONSTANT


New Draft = Old Density

Old Draft New Density


FOR A SHIP SHAPED VESSEL WHEN DRAFT CONSTANT


New Displacement = New Density

Old Displacement Old Density


TO KEEP THE AFT DRAFT CONSTANT


d = L x MCTC

la x TPC ….keeping the aft draft constant


d = L x MCTC

lf x TPC ….keeping the fwd draft constant


d = Distance from the CF

la = Distance from the AP

lf = Distance from the FP


TO PRODUCE A REQUIRED TRIM


Change in Draft (cms) = ( l. x w x d ) ± w .

L MCTC TPC

( - ive for Draft Aft)

( + ive for Draft Fwd)

( la for aft and lf for fwd)


Trim (cms) = W (LCB - LCG)

MCTC


(Values for LCB, LCG and MCTC should be final)

COT WITH CHANGE OF DENSITY


COT = W(RD1 – RD2)(LCF – LCB)

RD1 x MCTC2


LCGINITIAL = LCB ± ( Trim (cms) x MCTC )

W

….( - ive for stern trim )

….( + ive for head trim )


TRIM EFFECT AFT = la x Trim

L


TRIM EFFECT FWD = lf x Trim

L


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BILGING


WHEN HEIGHT OF COMPARTMENT IS GIVEN AND ABOVE WATER LEVEL

CALCULATE SINKAGE BY RECOVERABLE BUOYANCY METHOD:








Sinkage = Buoyancy still to be recover

L x B


Buoyancy still to be recover = Lost buoyancy – Recoverable

Buoyancy

Volume of Lost Buoyancy = l x b x draft


Recoverable Buoyancy = ( L – l ) x B x ( Depth – Draft )


To find the Final Draft, add the Sinkage to Tank’s height



WHEN IN QUESTION PERMEABILITY OF THE CARGO IS GIVEN

CALCULATE THE EFFECTIVE LENGTH OF THE TANK:


Permeability ( m ) = Broken Stowage

Stowage Factor


Broken Stowage = Actual Stowage – Solid Stowage


Solid Stowage = 1 .

R.D of liquid in tank


Effective Length = Tank’s length ORIGINAL x Permeability ( m )


NB

After calculating ‘Effective length’ always use this length for tank’s length.


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BILGING


MIDSHIP COMPARTMENT


NON WATER TIGHT WATER TIGHT


Sinkage = v .

A - a …If NON WATER TIGHT


Sinkage = v .

A …If WATER TIGHT


BM = LB3

12V …If WATER TIGHT


BM = (L – l)B3

12V …If NON WATER TIGHT




BILGING


SIDE COMPARTMENT







PLAN VIEW OF A SHIP


Sinkage = v .

A - a …If NON WATER TIGHT


Sinkage = v .

A …If WATER TIGHT


TANq = BB1

GM ….q = List


BB1 = a x d

Final A ….d = Distance from center of tank to

ship’s center line

….Final A = A - a

BM = IOZ

V


IOZ = IAB - Ad2 ….d = B + BB1

2

….A = A - a

IAB = LB3 - lb3

3 3

BILGING





END COMPARTMENT



AFT COMP. BILGED FWD COMP. BILGED

NON WATER TIGHT NON WATER TIGHT


Sinkage = v .

A - a …If NON WATER TIGHT


Sinkage = v .

A …If WATER TIGHT


If ‘KG’ is not given, then GML = BML


BM = L3B

12V …If WATER TIGHT


BM = (L – l)3B

12V …If NON WATER TIGHT


COT = w x d

MCTC ….w = l x b x dft x R.D

….d = L ..(Non water tight case)

2

….d = tank’s center to CF

..(Water tight case)



MCTC = WGML

100L


COD Aft = la x COT

L ….la = ( L - l ) + tank’s length

2

(For measuring the CF from AP) ..(Non water tight case)

…. la = L

2

(CF hasn’t changed and is amidships) ..(Water tight case)


When Fwd compartment is bilged (and non water tight), then just use

….la = ( L - l )

2

(Again for measuring the CF from AP) ..(Non water tight case)


IN CASE OF WATER TIGHT COMPARTMENT BELOW WATER LINE AND BELOW THE TANK THERE IS AN EMPTY COMPARTMENT





a) Deal as normal water tight case

b) Use volume of the tank only which is filled with water but not the portion beneath it.

c) But for KB of tank, use from K to center of tank


NB

IN WATER TIGHT CASE

· BM remains the same before and after

· KB is different before and after bilging

KB1 is half of Original Draft

KB2 is found by moments


IN NON WATER TIGHT CASE

· BM is different before and after bilging

BM1 is LB3 and BM2 is (L - l)B3

12V 12V


· KB is different before and after bilging

KB1 is half of Initial Draft

KB2 is half of New Draft



PLEASE NOTE THE FOLLOWING CONDITIONS







WATER TIGHT CASE NON WATER TIGHT CASE

Calculate:

a) Sinkage by non w/t method

b) KB2 by Moments


NB:

In all cases of WATER TIGHT COMPARTMENT, calculate KB by the MOMENTS METHOD& use ‘New Draft’ in calculating this KB when calculating volume.



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TANKER CALCULATIONS


TOTAL OBSERVED VOLUME (T.O.V.):

The Total Observed Volume of all Petroleum Liquids and Free Water at observed temperature.


GROSS OBSERVED VOLUME (G.O.V.):

The Total Volume of all Petroleum Liquids, excluding Free Water at observed temperature.


G.O.V. = T.O.V. - Vfw (at observed temperature)


GROSS STANDARD VOLUME (G.S.V.):

The Total Volume of all Petroleum Liquids, excluding Free Water, corrected by appropriate Volume Correction Factor for the observed temperature and API Gravity 60º F, Relative Density 60º F / 60º F or Density 15º C.


G.S.V. = G.O.V. X V.C.F.


FREE WATER (Vfw):

The volume of water present in a tank which is not in suspension in the contained liquid at observed temperature.


ONBOARD QUANTITY (O.B.Q):

Quantity of water, oil, slops, residue, sludge or sediment, remaining in the tanks prior to loading.


TOTAL CALCULATED VOLUME (T.C.V.):

It is the Gross Standard Volume plus Free Water.


T.C.V. = G.S.V. + Vfw


TOTAL RECEIVED VOLUME (T.R.V.):

Is equal to the Total calculated Volume minus O.B.Q.

Weight Correction Factor (W.C.F.) is applied to this Volume to obtain Weight in Metric Tons or Long Tons.

Shore Gross B/L figure is to be compared with this figure.

Whenever Free Water is found in Cargo:


T.R.V. = T.C.V. - O.B.Q.


LOADED OIL WEIGHT:

Is equal to the Gross Standard Volume minus O.B.Q.

Weight Correction Factor is applied to this Volume to obtain weight in Metric Tons or Long Tons.

Shore Gross B/L figure is to be compared with this figure when no Free Water is found in Cargo.


LOADED OIL WEIGHT = (G.S.V. - O.B.Q.) W.C.F.


VESSEL’S EXPERIENCE FACTOR (V.E.F.):

Is equal to the Total of Gross B/L figures divided by the Total of Ship’s figures over the last 10 voyages.


For the purpose of calculating V.E.F., 10 TO 20 Voyages may be taken. However all voyages must ‘qualify’. A minimum of 5 ‘qualified’ voyages is needed for some level of V.E.F.


The defination of a “qualified voyage is one that meets the following criteria:

· Any voyage that is within +/- 0.0030 of then average ratio of all voyages listed. (eg. If the average listed is 1.00105, then all voyages within the range 0.99805 through 1.00405 would qualify)

· Excludes all voyage prior to any structural modification which affected the vessel’s cargo capacity.

· Excludes load or discharge data where shore measurements were not available.


This Factor is not to be applied to ship’s figure for assessing Ship / Shore difference.


The Factor may be applied to Ship’s figure to obtain an approximate B/L figure, only as a counter check where:


SHIP’S FIGURE X V.E.F = APPROXIMATE B/L FIGURE.


TABLES, VOLUME AND DENSITY:

API = AMERICAN PETROLEUM INDEX


ASTM = AMERICAN STANDARD OF TESTING MATERIALS


Previously there were 3 versions of ASTM Tables:

· USA Version - Giving API at 60º F

· UK Version - Giving Specific Gravity at 60º / 60º F (Ratio of density of Oil at 60º F to density of Water at 60º F = Specific Gravity)

· Metric Version - Giving Density at 15º C (eg. 0.865 kg/m3)


IN PRACTICE:

Volume at observed temperature is calculated by taking ullages.


Density at 15º C is given by Shore authorities.


Now Volume at 15º C = Volume at observed temperature X V.C.F.


And Volume at 15º C X Density at 15º C = Weight at 15º C (IN VACUUM)


But we want Weight IN AIR, therefore we apply the W.C.F.


W.C.F. = DENSITY AT 15º C - 0.0011


NOTES:

Now all 3 Versions are combined together and made into total 14 Volumes which contain all calculations regarding CRUDE, LUBE OIL, DIESEL OIL and all kinds of fluids / liquids.

A particular ship may have selected Volumes only, for the trade on which she is being run.


HYDROMETER - TO MEASEURE DENSITY OF WATER

PICNOMETER - TO MEASURE DENSITY OF ANY LIQUID OTHER THAN WATER


SOLVED NUMERICALS:


1. Volume at observed temperature = 10000 m3

Density at 15º C. Use observed temperature = VCF

Volume at 15º C = 9000 m3 (Volume at observed temperature X VCF)

Therefore Weight in Vacuum = 9000 X 0.8 = 7200

Density at 15º C - 0.0011 = WCF

0.8 - 0.0011 = 0.7989

Therefore W = Volume at 15º C X 0.7989


OBQ = ON Board Quantity

ROB = Remaining On Board


TOV = Vo + Vfw at observed temperature

GOV = TOV - Vfw

GSV = GOV x VCF

TCV = GSV + Vfw

TRV = TCV - obq


TRU x WCF is the figure used to compare B/L figure.

(GSV – OBQ) x WCF = Weight of Oil Loaded


API at 60º F = 141.5 - 131.5

SG 60º / 60º F


API 10 is for fresh water.

Higher the API, the lighter the product


1m3 = 6.28981 barrels


6A A - stands for Crude Oil

6B B - stands for Product Oil



2. On commencement of discharge of No. 3 © tank at 1324, EK draft of 9.00 m, ullage of 0.20 m with waterdip 15 cm.

On completion of bulk discharge at 1800, sounding of 3 © was 20 cm.

The tank is box shaped with dimensions L = 14, B = 12, D = 10, density at 15º C = 0.8937

Average Cargo temperature = 26.0º C. Find the rate of discharge.


TOV = 14 x 12 x 9.8 = 1646.4 m3

Vfw = 14 x 12 x 0.15 = 25.2 m3

GOV = 1646.4 – 25.2 = 1621.2 m3

GSV = GOV x VCF = 1608.026 m3


By Interpolation:

0.8937

0.890 0.895

26º C 0.9918 0.9919

therefore VCF = 0.991874


WCF = 0.8937 - 0.0011 = 0.8926


Therefore Weight of oil on arrival = 1608.026 x 0.8926 = 1435.324 Tons

Volume ROB (0.2 x 14 x 12) x VCF x WCF = 29.747 Tons


Therefore Rate of Discharge in MT = (1435.324 - 29.747)

TIME



WEDGE FORMULA:

It is applicable to Center Tanks only and when the ship is upright and trimmed.













Refer to Figure 1.

Let Breadth of the tank = ‘b’, trim = 0º, dist. of ullage port from aft b/head = ‘d’, height of the tank = ‘h’.


In triangle DGB, angle DGB = 90º

DB = DG Cosec 0 [ DG = Sounding = Pm = Pmiddle ]

= Pm Cosec 0

EC = Dist of ullage port from aft b/head = d

Now, BE = EC + BD – CD

Therefore BE = (d + Pm Cosec 0 – h Tan 0) ………………………. (A)


BE is < / = AE [Wedge is formed]

EF = BE Tan 0

= (d + Pm Cosec 0 - h Tan 0) x Tan 0

Therefore Volume of Wedge = [1/2 x BE x EF] x b

Vwedge = [1/2 x BE x P] x b (B)


Now, Trim = 0

Therefore Tan 0 = Trim = T ………….(1)

Length L


Also from Figure 1

Tan 0 = EF (2)

BE


Comparing (1) and (2)

T = EF

L BE


Therefore BE = EF x L = P x L ………(3)

T T


Putting value of BE (3) in (B),


Vwedge = ½ x (P x L) x P x b

T


Vwedge = L x b x P2 Where P = EF = Ht. Of liquid at aft b/head

2T T = Trim

See Figure 2. below







IN CASE WHEN TRAPEZIUM IS FORMED INSTEAD OF WEDGE















Refer to Figure 3 as above.

Corrected Sounding (P) = {Obs. Sounding (P’) + [d – (h – T/L)] x T/L}


Area of Trapezium = [ (Pmax + z) + z] x l = [ 2P – Pmax] x l

1 2


Where P = Corrected sounding at aft b/head

P’ = Sounding observed from ullage port

d = Dist of ullage port from aft b/head

h = Height of the tank

T = Trim, L = Length of the ship, l = Length of the tank, b = Breadth of the tank


Pmax Max EF due to wedge


Pmax = T/L x l ………………………………….(1)


Pcorr. sdg = P’ + [ d – (h x T/L) ] x T/L ……….(2)


If (1) < (2) ie. Pmax < Pcorr. sdg


The instead of wedge, a trapezium is formed of volume…


Volume = [ Pmax + 2z ] x l x b

2


MORE NUMERICALS:


1. Given tank ullage = 37 cm

Observed temperature of Cargo = 19.3º C

Density of Cargo in Vacuum at 15º C = 0.857 t/m3

Water Content = 165 m3

Calculate amount of Cargo in the tank in MT.

TOV = 3014.9 m3 at 19.3º C

GOV = TOV - Vfw

GOV = 3041.9 – 165 = 2876.9 m3

GSV = 2876.9 x VCF

= 2876.9 x 0.9966

= 2867.1185 m3


WCF = 0.8570 – 0.0011 = 0.8559


Therefore amount of Cargo in MT = 2867.1185 x 0.8559

= 2453.967 MT



2. LBP = 150 M, Trim = 1.30 m

P’ = 58 cm = 0.58 m

d = 1.500 m, l = 12, b = 15, h = 19

R.D. = 0.89


Pmax = T/L x l = 1.3/150 x 12 = 0.104 m


Pcorr.sdg = P’ + [ d – (h x T/L) ] x T/L

= 0.58 + [ 1.5 – (19 x 1.3/150) ] x 1.3/150 = 0.592 m


Since Pmax < Pcorr.sgd, therefore a trapezoid if formed.


Area of Trapezium ABCF,

= ( 0.592 + 0.488 ) x 12 = 6.48 m2

2


Volume of the trapezoid = 6.48 x 15


Therefore amount of Oil in the tank = 6.48 x 15 x 0.89 = 86.508 MT



2. The vessel is on even keel

(A) Ullage = 0.43 m, Water dip = 0.12 m

Density at 15º C = 0.8572

Observed temperature = 33.5º C


For ullage 0.43 m,

Tov = 1955.0 m3

Vfw = 14.8 m3


Therefore GOV = TOV – Vfw = 1940.2 m3

VCF = 0.985388

GSV = GOV x VCF = 1940.2 x 0.985388 = 1911.8498


WCF = 0.8572 – 0.0011 = 0.8561


Therefore the amount of Cargo = 1911.8498 x 0.8561


(B) At the end of discharge,

Ullage = 10.3 m, Sdg = 0.20 m = P’

Trim = 2 m, l x b x h = 20 x 8 x 10.5

d = 1.000 m, LBP = 150


Pmax = T/L x l = 2/150 x 20 = 0.266


Pcorr.sdg = P’ + [ d – (h x T/L) ] x T/L

= 0.20 + [ 1.0 – (10.5 x 2/150) ] x 2/150 = 0.21466


Since Pmax > Pcorr. sdg, therefore a wed ge is formed


P = BE Tan 0 = [ d + Pm Cosec 0 – h Tan 0 ] x Tan 0.


(Tan 0 = 2/150. Therefore 0 = 0.1458. Cosec 0 = 81.404 )


P = [ 1.0 + 0.2Cosec 0 – 10.5 x 2/150] x 2/150

= [ 1.0 + 0.2 x 81.404 – 10.5 x 2/ 150 ] x 2/150 = 0.22854


Volume of wedge = L x b x P2 = 150 x 8 x (0.228544 x 0.228544)

2T 2 x 2


Therefore Volume of wedge = 15.6697 m3


3. l x b x h = 40 x 20 x 20 m3

Ullage of oil = 1.24 m Trim = 3 m

Height of ullage point = 1.10 m LBP = 200 m

Depth of free space above oil = 0.14 m d = 1.6 m

Depth of oil = P’ = 19.86 m

Water dip = 21.1 – 20.94 = 0.61 m


Pmax = T/L x l = 3/20 x 40 = 0.60 m


Pcorr.sdg = { [P’] + [ (d – h x T/L) ] x T/L }

= [ 19.86 + ( 1.6 – 20 x 3 / 200) x 3 / 200 ] = 19.8795


Since Pmax < Pcorr.sdg, a trapezium is formed.


Volume of trapezium = ( 19.2795 – 19.8795) x 40 x 20 = 15663.8 m3

2

Now considering the water dip,

Pmax = EF /AE = T/L

Pmax = 3/200 x 40 = 0.60 m


Present P’ = ( d + Pm Cosec 0 – h Tan 0) x Tan 0

= ( 1.6 + 0.16 x 66.901 – 20 x 0.015 ) x 0.015 = 0.180 m


Since Pmax > P a wedge is formed


Volume of wedge EBF = L x b x P2/ 2T = 200 x 20 x 0.18 x 0.18/ 2 x 3 = 21.6 m3


TOV = 15663.8 m3

Vfw = 21.6 m3

GOV = 15642.2 m3

VCF = x 0.980784

GSV = 15341.619 m3

WCF = x 0.8135


Therefore amount of oil in Tonnes = 12480.407 MT