**BARGES DRAFT SURVEY ( Draft Survey Tongkang )**

Before we explain the following barges draft survey, we provide

simple application to calculate the barge draft survey.

Just calculate no print out result.

Here is a draft survey barge display applications that can be

downloaded at the following address (54 kb ) :

Here with detail application to calculate discharging the barge draft survey.

with print out and compare Bill of Lading Figure.

Barges 230 Feet

Barges 300 Feet

Barges 250 Feet

Install komponen for system 32 only

Contact Us : sudarmanto.clg@gmail.com

**BARGES DRAFT SURVEY PROCEDURE**

**This Survey Procedure is International Standard for any type of barges.**

The Forward (Fwd), Aft (Aft), and Mid (Mid) drafts are read at both Port (P) and

Starboard (Stbd) marks. The P and S readings are added, and the result divided by two.

The Aft draft is subtracted from the Fwd draft, and the result is Apparent Trim.

If Trim is positive, Barges is trimmed By the Head; if Trim is negative, Barge is

trimmed By the Stern.

Fwd Draft =

2

Aft Draft =

2

Mean Mid =

2

Trim = Fwd – Aft

The Quarter Mean ( QM ) or Mean Draft Corrected for Deformation must be solved next.

Use the corrected draft values

First calculate the Fwd/Aft Mean Draft. Add Fwd to Aft, and divide the result by two:

Fwd /Aft Mean =

2

Next, calculate the Mean of Mean Add the Fwd/Aft Mean to the Mid Mean, and divide the

**APPARENT TRIM**The Forward (Fwd), Aft (Aft), and Mid (Mid) drafts are read at both Port (P) and

Starboard (Stbd) marks. The P and S readings are added, and the result divided by two.

The Aft draft is subtracted from the Fwd draft, and the result is Apparent Trim.

If Trim is positive, Barges is trimmed By the Head; if Trim is negative, Barge is

trimmed By the Stern.

Fwd Draft =

__Fwd(P) + Fwd(S)__2

Aft Draft =

__Aft(P) + Aft(s)__2

Mean Mid =

__Mid(P) + Mid(s)__2

Trim = Fwd – Aft

**BARGES NO NEED DRAFT CORRECTIONS****MEAN DRAFT CORRECTION**The Quarter Mean ( QM ) or Mean Draft Corrected for Deformation must be solved next.

Use the corrected draft values

First calculate the Fwd/Aft Mean Draft. Add Fwd to Aft, and divide the result by two:

Fwd /Aft Mean =

__Fwd + Aft__2

Next, calculate the Mean of Mean Add the Fwd/Aft Mean to the Mid Mean, and divide the

**result by two:**

Mean of Mean =

2

and divide the result by two

QM =

2

Refer to barges Hydrostatic Tables for the following values:

TPC: tonnes per Centimetre Immersion

MTC: Moment to change Trim One Centimetre

Lcf: Longitudinal centre of Flotation

Calculate the Displacement Correction ( DISP. Corr.)

1) Subtract the nearest smaller Draft from the calculated QM.

2)Multiply the result by 100 to convert Meters to Centimetres.

3) Multiply this by the TPC for the displacement.

4) This correction is added to the displacement given for the nearest smaller draft.

Draft Remainder (cm) = Draft remainder x 100

DISP. Corr. = TPC x Draft remainder (cm)

Displacement = DISP. + Corrected. = Actual Displacement

TRIM CORRECTION

Before calculating the First Trim Correction, Corrected Trim (CT) must be converted

from meters to centimetres. Multiply CT (in) by 100 to get centi-metres.

To calculate the First Trim Correction, multiply TRIM by TPC, then multiply the product

by the longitudinal Centre of Flotation (LCF) x 100. Then, divide the final product

by the Length Between Perpendiculars (LBP).

CT = CT x 100

First Correction =

LBP

Second Correction =

LBP

The first correction can be either positive (add), or negative (subtract), depending

on the location of the LCF and the trim condition. (It's mean sign of Lcf and TRIM )

TRIMMED BY THE HEAD Lcf is Forward (Fwd) (+) ADD Trim Correction

Lcf is Aft (Aft) (-) SUBTRACT Trim Correction

TRIMMED BY THE STERN Lcf is Fwd (—) SUBTRACT Trim Correction

Lcf is Aft (+) ADD Trim Correction

divided by 100. It may be applied without adverse effect at smaller trims.

The second correction is always (+) (additive) regardless of the trim or other factors.

Before calculating the Second Trim Correction, MTC differ-ence, sometimes referred

to as dM/dZ, must be found.

ADD 50 cm to the Quarter Mean Draft ( QM ) to find the corresponding MTC from

barges Hydrostatic Tables .

SUBTRACT 50 cm from the Quarter Mean Draft (QM) to find the corresponding MTC

from barges Hydrostatic Tables ..

How to find MTC diff in the Hydrostatic Tables :

a) Q M + 50cm = MTC ( Found in barges Hydrostatic Tables .)

b) Q M - 50cm = MTC ( Found in barges Hydrostatic Tables .)

MTC diff = ( a) — ( b)

a) QM = 3.675

4.175 MTC = 169.4

b) QM = 3.675

3.175 MTC =160.7

(a) = 169.4

(b

MTC diff = 8.7

SEA WATER

A Specific Gravity (SG) of 1.025 is generally assumed

for SeaWater in calculating Displacement (DISP). Because the Sg. is almost never exactly

1.025, Sg. correction must be calculated.

Sg. is always minus if the measured Sg. is 1.025 or less.

Calculate the Sg. correction by subtracting the measured density from 1.025, divide

this by 1.025 and then multi-ply that answer by the DISP.

Sg. corr. =

1.025

The Final Survey follows the same procedure as the Initial Survey. Total cargo equals

Mean of Mean =

__Fwd/Aft Mean + Mid Mean__2

**Now calculate the QM Add the Mean of Mean to the Mid Mean,**and divide the result by two

QM =

__Mean of Mean + Mid Mean__2

Refer to barges Hydrostatic Tables for the following values:

TPC: tonnes per Centimetre Immersion

MTC: Moment to change Trim One Centimetre

Lcf: Longitudinal centre of Flotation

**Interpolation**Calculate the Displacement Correction ( DISP. Corr.)

1) Subtract the nearest smaller Draft from the calculated QM.

2)Multiply the result by 100 to convert Meters to Centimetres.

3) Multiply this by the TPC for the displacement.

4) This correction is added to the displacement given for the nearest smaller draft.

Draft Remainder (cm) = Draft remainder x 100

DISP. Corr. = TPC x Draft remainder (cm)

Displacement = DISP. + Corrected. = Actual Displacement

TRIM CORRECTION

Before calculating the First Trim Correction, Corrected Trim (CT) must be converted

from meters to centimetres. Multiply CT (in) by 100 to get centi-metres.

To calculate the First Trim Correction, multiply TRIM by TPC, then multiply the product

by the longitudinal Centre of Flotation (LCF) x 100. Then, divide the final product

by the Length Between Perpendiculars (LBP).

CT = CT x 100

First Correction =

__TRIM x TPC x Lcf x 100__LBP

Second Correction =

__T__^{2}+/-50 cm x MTC diff.LBP

The first correction can be either positive (add), or negative (subtract), depending

on the location of the LCF and the trim condition. (It's mean sign of Lcf and TRIM )

TRIMMED BY THE HEAD Lcf is Forward (Fwd) (+) ADD Trim Correction

Lcf is Aft (Aft) (-) SUBTRACT Trim Correction

TRIMMED BY THE STERN Lcf is Fwd (—) SUBTRACT Trim Correction

Lcf is Aft (+) ADD Trim Correction

**The second Trim Correction is required when the Trim is greater than the LBP**divided by 100. It may be applied without adverse effect at smaller trims.

The second correction is always (+) (additive) regardless of the trim or other factors.

Before calculating the Second Trim Correction, MTC differ-ence, sometimes referred

to as dM/dZ, must be found.

ADD 50 cm to the Quarter Mean Draft ( QM ) to find the corresponding MTC from

barges Hydrostatic Tables .

SUBTRACT 50 cm from the Quarter Mean Draft (QM) to find the corresponding MTC

from barges Hydrostatic Tables ..

How to find MTC diff in the Hydrostatic Tables :

a) Q M + 50cm = MTC ( Found in barges Hydrostatic Tables .)

b) Q M - 50cm = MTC ( Found in barges Hydrostatic Tables .)

MTC diff = ( a) — ( b)

a) QM = 3.675

__+ 0.50__4.175 MTC = 169.4

b) QM = 3.675

__- 0.50__3.175 MTC =160.7

(a) = 169.4

(b

__)__=__- 160.7__MTC diff = 8.7

SEA WATER

**SPECIFIC GRAVITY (SG) CORRECTION**A Specific Gravity (SG) of 1.025 is generally assumed

for SeaWater in calculating Displacement (DISP). Because the Sg. is almost never exactly

1.025, Sg. correction must be calculated.

Sg. is always minus if the measured Sg. is 1.025 or less.

Calculate the Sg. correction by subtracting the measured density from 1.025, divide

this by 1.025 and then multi-ply that answer by the DISP.

Sg. corr. =

__1.025 - Measured Density x DISP__.1.025

**FINAL SURVEY**The Final Survey follows the same procedure as the Initial Survey. Total cargo equals

**DISP. minus Lightship Weight.**

# See you at the next blog .....SHIP'S DRAFT SURVEY

# See you at the next blog .....SHIP'S DRAFT SURVEY

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