Draft survey report: what goes in it, with a worked example

A draft survey report is the surveyor's written record of a draft survey. It states who measured what, where and when, lists every reading and correction, and ends with the cargo weight and the signatures. The UNECE draught survey code treats it as equivalent to a weight certificate, and a report that shows only the final figure cannot be checked by anyone else.

How the figures themselves are calculated is explained in what a draft survey is.

What a draft survey report must contain

The UNECE code for draught surveys of coal cargoes (1992), which recommends its procedure for dry cargoes generally, asks the report to show how the survey was conducted, which calculations were made and any problems met. In substance, that means:

• Identification. The surveying firm, the survey number, the vessel with flag, year of build and classification register, who requested the survey, on whose account, and anyone else attending: a joint surveyor, an umpire, or a monitor for buyer or seller.
• Place and time. Port and berth, the date and hours of both surveys, and the conditions: weather, sea, wind, tide, and current where it matters.
• The ship's documents. Which hydrostatic and tank tables were used, issued by whom and dated, and whether the trim corrections came from tables or from formulas.
• Every reading. Six drafts per survey, the dock water density with the hydrometer's serial number, and each tank sounding with its volume, density and weight.
• Every correction on its own line, from the drafts at the perpendiculars to the density correction.
• The deductibles, item by item, and the net displacement at each survey.
• The cargo statement, and at the survey without cargo, the constant.
• Observations. Unusual situations, departures from the code, and the reasons if the survey could not be carried out.
• Signatures. The surveyor signs or initials every page; the code recommends that the master, or the chief officer and chief engineer, sign as witnesses.

This is the report for one method. What any cargo survey report should contain, whatever the method, is in what a cargo survey report must contain.

Worked example: the report for 33,329.946 MT of soyabean meal

Our draft survey form's example, laid out as a report. The vessel, parties and conditions are fictitious; the hydrostatic figures are illustrative.

Report details
Surveying firm / survey no.	[firm] / [no.]
Vessel	m.v. EXAMPLE; LBP 180.00 m, fore marks 3.00 m aft of FP, aft marks 5.00 m forward of AP, LBM 172.00 m
Port / berth	Rotterdam / [berth]
Cargo	Soyabean meal in bulk, loading
Initial / final survey	day 1, 07:30–09:10 / day 3, 16:40–18:05
Conditions	light wind, no swell, rising tide, current negligible
Documents used	ship's hydrostatic and tank tables [issuer, date]; trim corrections by formula
Hydrometer	draught survey hydrometer, calibrated in air, no. [serial]

Figures	Initial	Final
Drafts forward port / starboard (m)	4.18 / 4.22	10.98 / 11.02
Drafts midships port / starboard (m)	5.58 / 5.62	11.28 / 11.32
Drafts aft port / starboard (m)	6.98 / 7.02	11.58 / 11.62
Drafts at FP / AP (m)	4.1512 / 7.0814	10.9895 / 11.6174
True trim, by the stern (m)	2.9302	0.6279
Quarter mean draft (m)	5.604	11.301
Dock water density (t/m³)	1.0210	1.0210
D(T) at quarter mean (MT)	21,450	46,800
TPC (MT/cm) / LCF (m, + aft)	32.5 / +2.1	36.8 / +1.4
MTC at +50 / −50 cm (MT·m/cm)	285 / 272	512 / 498
First trim correction (MT)	+111.105	+17.972
Second trim correction (MT)	+31.006	+1.533
Displacement corrected for trim (MT)	21,592.111	46,819.505
Density correction (MT)	−84.262	−182.710
Displacement corrected for density (MT)	21,507.849	46,636.795
Ballast / fresh water (MT)	8,450 / 210	320 / 185
Fuel / diesel / lubricating oil (MT)	580 / 45 / 12	540 / 40 / 11
Bilges, slops, other (MT)	8	8
Total deductibles (MT)	9,305.000	1,104.000
Net displacement (MT)	12,202.849	45,532.795

Cargo statement. 45,532.795 − 12,202.849 = 33,329.946 MT. Bill of lading weight, for information: 33,400.000 MT; difference −70.054 MT, or −0.210%.

Observations. All ballast tanks sounded with steel tape and paste, no hold ballast. Bill of lading weight entered after the calculation and not used in it.

Signatures. Surveyor, on each page, with name in print. Master, as witness to the readings and to the ship's data supplied.

The example is condensed. A full report attaches the tank sheets, with each tank's sounding, volume, density and weight, and, since the initial survey here is made without cargo, the constant: the corrected displacement less deductibles and the lightship weight from the ship's booklet. Our example vessel has no lightship figure, so the constant is not shown.

The code asks for figures to two decimals and density to four. We show drafts at the perpendiculars and trim to four decimals, the quarter mean and calculated tonnes to three, and input figures as entered; all steps are computed unrounded and rounded half up for display, so a line recomputed from rounded figures can differ in the last decimal.

Why every step has to be visible

The code's forms exist partly to make reports auditable. Suppose the LCF had been entered with the wrong sign at both surveys: our calculation in what a draft survey is shows the cargo would then come out some 185.5 MT higher. On the report above, anyone can see the sign next to the LCF and recompute the two trim corrections. On a report that gives only the cargo line, nobody can.

Britannia P&I (2023) puts the same burden on the ship: officers should check the calculation against their own at every stage, clear up disagreements immediately, and not sign a report they do not agree with. Video and photographs of the draft readings, it adds, can prove them later.

The bill of lading figure and the shore scale

Our example shows the bill of lading weight because the reader will ask for it. The code does not mention the bill of lading figure. It allows a shore scale figure on the report for statistical purposes only, and states that it must not influence the weight the surveyor measured. We treat the bill of lading weight the same way: information, not an input.

A difference of −0.210% is smaller than the 0.5% accuracy the code expects when approved vessel data and qualified surveyors are available. Britannia P&I warns that a draft survey and a shore scale are different methods, so which figure binds belongs in the charter party. Where the figures do point to a shortage, the draft survey report becomes one piece of evidence next to the outturn report and a timely letter of protest; for other weight documents, see weight certificates.

FOSS

FOSS is software for inspection companies and the port, with a sector specialist at the table. Readings are entered once, on board and offline if need be, and nine report types come from that same input. An outturn more than 0.5% short of the bill of lading weight flags a protest automatically.