In this post limits to how to conduct the Bunker Survey on the ship tanks only.
 Notes Book,
 Sounding Tape,
 Thermometer,
 Density Meter for Oil (),
 Oil and Water Paste,
 Petroleum ASTM Table 54B (for Product Oil) and Table 56,
 Flashlight,
 Sampling Can,
 Bottle or Can for Sampling (if required taken samples).
Identify and records the number and Depth of Tank, Reference Height, and Measuring Method recommended to use (Ullage or Sounding) for each Oil Tank. Sounding is determined the level of liquid tank from the bottom of the tank to the liquid surface (typically applied for light liquid).
Ullage means to determine the level of liquid of tank by measured the empty space from top of the Tank (the mouth of Sounding Pipe) to the liquid surface (typically applied for heavy liquid). The both methods will point to the same result.
Record the Last Bunker Report, Time and Place of last Bunker supplied, includes the Oil density.
Records the quantity of bunker onboard when the ship arrives at Port (arrival Condition) as per Engine Log Book.
Checking the accuracy of the Sounding Tape, it is recommended to use your own Sounding Tape. In case we used Ship’s Sounding Tape, please checking the tape.
Sounding each Oil Tank and records the level of Oil on the tank. Attached the sounding Tape with Oil Paste to make easy and clear to show of oil level (recommended for Light Oil).
Check the Ship’s Draft Marks to get the Ship Trim for Trim correction, and check the ship Inclination or Listing for List Correction, that is required to calculate the Tank Quantity Table.
Taken Oil sample, check temperature and oil density, for the accessible tank only. The Service and Settling Tanks are not accessible due to the oil on that tanks were in heating condition at the high temperature. We could records the tank gauging for determining the quantity, the temperature at the thermometer available on each tank, and the Oil Density from the Engine Log Book. If you could not taken the oil sample for checking density, it is recommended to calculate the Density Commingle, by means the Combine Density between two Oils (Old and New Oils) that has mixed on one tanks which they have different in Density. Where it is approaching the actual oil density, the pattern is {(Old Oil Quantity x Oil Density / Total Oil on Tank) + (New Oil Quantity x Oil Density / Total Oil on Tank)}.
Calculations, this stage will involved the Sounding level of each tank, Ship’s Trim and List, Tank Quantity Table (provided by Ship’s Chief Engineer), Oil Density and Temperature, ASTM Table 54B to ascertain the Volume Correction Factor (VCF – to convert from Cubic Meter to Kiloliter) and ASTM Table 54B for Weight Correction Factor (WCF – to convert from Kiloliter to Metric Ton).
Example to calculate Density Commingle: FO Tank No. 1 C, total oil on tank 400 Cu.M, Old Oil 200 Cu.M with density 0.9870, and New Oil 200 Cu.M with density 0.9720. Density Commingle = {(200 x 0.9870 / 400) + (200 x 0.9720 / 400)} = 0.4935 + 0.4860 = 0.9795.
Issued the Tank Sounding and Bunker Report.
The Draft Survey procedures and calculation ascertained as the following series :
 Reading the draftmark of the ship, which consist of six (6) points of draftmarks, i.e.; Fore, Midship, and After at both sides of the ship,
 Sampling and testing the sea water or dock water density at the place where the vessel floats,
 Determining of deductible weights by measuring and sounding of ballast tanks, fuel oil, fresh water that existing onboard at the time of survey,
 Using Hydrostatic Table provided onboard to calculation.
 Forward Port Side (FP),
 Forward Starboard Side (FS),
 Midship Port Side (MP),
 Midship Starboard Side (MS),
 Aftward Port Side (AP),
 Aftward Starboard Side (AS),

Raw Draft Calculation; Fore Mean or Fm = (FP+FS)/2, Mid Mean or Mm = (MP+MS)/2, and Fore Mean or Am = (AP+AS)/2. while Apparent Trim or AT = Am – Fm. the Apparent Trim is the Trim that visually find.

Draftmark posision and correction to perpendicular. As the ship draftmark is not placed at the perpendicular, the Fore and After draft should be corrected with distance from the draftmark to perpendicular. The correction rules is: if the Trim by Stern, the Fore correction should be minus and After correction plus, and if the Trim by Head (stem), the Fore correction should be plus and After correction minus. The Midship correction is parallel with the fore correction with the same pattern. Some Hydrostatic table provided with these correction result. But if not the reference pattern is for Fore Correction or Fc = (Fd x AT) : LBM and After Correction or Ac = (Ad x AT) / LBM. Where Fd = Fore distance to perpendicular, Ad = After distance to perpendicular, and LBM = Length Between Mark or Length between Fore and After draftmarks or LBM = LBP – (Fd + Ad).

True Draft Calculation / Draft Corrected; Fore draft corrected or Fcd = Fm + Fc, Mid draft corrected or Mcd = Mm + Mc, and After draft corrected or Acd = Am + Ac.

True Trim or TT : Actual Ship Trim after draft corrected or TT = Acd – Fcd.

Fore and After Mean Draft or FAm = (Fcd + Acd)/2, Mean of Mean Draft or MM = (FAm + Mcd)/2, and Mean of Mean of Mean Draft or MMM or Quarter Mean = (MM + Mcd)/2.

The above calculation is similar with : MMM = {(Fcd x 1) + (Acd x 1) + (Mcd x 6)}/8.

Coresponding to the MMM or Quarter Mean result, the surveyor could check the value of needed parameters on Hysdrostatic table like; Displacement, TPC, LCF, and MTC. Records them accurately.

Get the Displacement or Disp.

First Trim Correction or FTc = (TT x LCF x TPC x 100) / LBP. Could be plus or minus depend on LCF.

Second Trim Correction STc = (TT x TT x MTC x 50) / LBP. The result always plus (+).

Displacement corrected by Trim or DispT = D – (FTc + STc).

Density Correction or Denc = DispT x {(Aden – 1.025) / 1.025}. where the Aden is Actual Density that surveyor has taken sampling and testing previously. The density correction commonly in minus (), due to the Actual Density is usually lower than 1.025 (fresh sea water). In case of at some port where the water salinity is high, the density correction could be plus (+).

And we have got the Displacement corrected by Density or DispDenc = DispT + Denc. (after corrected by density we will get the actual ship weight as per shown by Draft Survey).

Deductible Calculation. The same as draft, the deductible also need to corresponding to the table that named Tank Table / Tank Capacity Table. Refer to the sounding records that done before, the surveyor could be calculate the total deductbile existing onboard. Total Deductible or Deduct = Ballast Water + Fresh Water + Bilges + Fuel Oil + Diesel Oil, this total should be minus to the Displacement corected by Density.

The Net Displacement or NDisp = DispDenc – Deduct.

The Net Displacement is the actual ship weight after minus with deductible weight. For Unloading, to estimate the quantity of cargo onboard, the Net displacement should be minus withLight Ship and Constant.
Special Thanks to Capt. Harry González