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Cargo Surveying • Draft Survey • Bulk Cargo
Draught Surveying Course & Complete Draft Survey Guide
Learn how draught surveys are used to determine bulk cargo quantity through vessel displacement, hydrostatic data, density corrections, ballast and consumable adjustments, calculation checks and professional survey reporting.
Online 52 Hours 2 Sections • 4 Lessons • 1 Quiz Advanced Diploma Pathway
Course at a Glance
Expert in Draught Surveying Online Training
The current IMT programme combines three compulsory cargo-survey subjects with a specialist draught-surveying lesson and quiz.
Listed Duration
52 hours
Current course-page study time.
Current Structure
2 sections • 4 lessons • 1 quiz
Three compulsory subjects plus speciality training.
Training Area
Advanced Diploma Cargo Surveying
Specialist draught-survey pathway.
Fundamentals
What Is a Draught Survey?
A draught survey determines the weight of cargo loaded or discharged by calculating the change in a vessel's displacement before and after the cargo operation.
The method is widely associated with bulk commodities because direct weighing of a complete shipload may not be practical. The surveyor establishes the vessel's displacement from observed draughts and approved hydrostatic information, then accounts for ballast water, fuel, fresh water and other variable weights.
The reliability of the final cargo figure depends on careful observations and calculations. Small errors in draught reading, water density, tank quantities, hydrostatic interpolation or vessel condition can influence the result, so the survey needs a disciplined and transparent calculation process.
Draught surveying determines cargo quantity; it does not replace the safety requirements governing the carriage of solid bulk cargoes. For solid bulk cargo operations, current applicable requirements such as the IMSBC Code must be considered separately.
Calculation Logic
How Does a Draught Survey Calculate Cargo Weight?
1. Read Draughts
Observe forward, midship and aft draughts on both port and starboard sides where practicable.
2. Correct Observations
Apply relevant corrections for trim, list and draught-mark positions as required by the calculation method.
3. Determine Displacement
Use the vessel's approved hydrostatic tables or curves to establish displacement.
4. Correct for Water Density
Adjust displacement where dock-water density differs from the reference density used by the hydrostatic data.
5. Determine Deductibles
Establish ballast, fuel, fresh water and other variable weights not representing cargo.
6. Calculate Net Condition
Derive the vessel's relevant net displacement before or after cargo operations.
7. Compare Surveys
Subtract the light/initial condition from the loaded/final condition, or vice versa, to determine cargo change.
8. Verify & Report
Cross-check arithmetic, assumptions and evidence before issuing the final survey figure.
Accuracy
What Can Affect Draught Survey Accuracy?
- Sea state, swell or vessel movement affecting draught readings
- List or unusual trim
- Poorly visible or damaged draught marks
- Incorrect dock-water density
- Uncertain ballast or consumable quantities
- Tank calibration or sounding uncertainties
- Use of incorrect hydrostatic data
- Interpolation and arithmetic errors
- Changes in vessel stores or other variable weights
- Inconsistent timing between observations and tank measurements
Survey Evidence
Key Information Used in a Draught Survey
Draught Readings
Observed vessel draughts at the required positions.
Hydrostatic Tables
Approved vessel data linking draught/trim conditions with displacement and hydrostatic properties.
Water Density
Measured density of the water in which the vessel is floating.
Ballast Quantities
Soundings, ullages, calibration data and relevant ballast-water information.
Fuel & Fresh Water
Quantities of consumables that affect displacement but are not cargo.
Lightship / Constants
Relevant vessel weights and documented constants used in the survey calculation.
Cargo Operation Timing
Clear identification of initial and final survey conditions.
Survey Report
Complete record of readings, calculations, qualifications and the final quantity conclusion.
Solid Bulk Cargo Context
Draught Surveying and the IMSBC Code
The draught survey establishes quantity, while the IMSBC Code governs safety issues associated with solid bulk cargoes.
IMO's current publications list the IMSBC Code & Supplement, 2025 Edition. Amendment 07-23 became mandatory on 1 January 2026, while Amendment 08-25 may be applied voluntarily from 1 January 2026 before its envisaged mandatory entry into force on 1 January 2027.
Surveyors involved with bulk cargo should distinguish commercial quantity determination from cargo-safety responsibilities such as cargo declaration, moisture-related hazards, stowage and handling requirements.
Learning Focus
What You Should Learn from Draught Surveying Training
- Purpose and application of draught surveying
- Vessel displacement and hydrostatic principles
- Reading and correcting vessel draughts
- Trim and list awareness
- Water-density measurement and correction
- Ballast and consumable calculations
- Use of hydrostatic tables and curves
- Initial and final survey calculations
- Common sources of survey error
- Cross-checking and calculation quality control
- Marine cargo survey practice
- Essential legal context for cargo surveyors
- Technical report writing
- Professional independence and evidence management
Who Should Enroll
Who Is the Draught Surveying Course For?
Cargo Surveyors
Professionals who determine bulk cargo quantity or support cargo inspections.
Marine Surveyors
Surveyors expanding into commercial cargo-quantity work.
Chief Officers
Deck officers involved in loading, ballast and cargo quantity operations.
Masters
Senior officers seeking stronger understanding of draught-survey calculations and disputes.
Port / Terminal Personnel
Professionals working with bulk cargo loading, discharge and quantity control.
Shipowners / Charterers
Personnel reviewing outturn figures, cargo claims and quantity discrepancies.
Commodity Traders
Commercial teams seeking a practical understanding of how shipload quantities are established.
Maritime Consultants
Professionals supporting bulk-cargo surveys, claims or technical investigations.
Current IMT Curriculum
How the IMT Expert in Draught Surveying Course Is Structured
Marine Cargo Survey Practices
Core cargo-survey techniques and professional survey context.
Essential Law for Cargo Surveyors
Legal and commercial context for cargo-survey assignments.
Technical Report Writing Skills
Evidence-based reporting and professional communication.
Expert in Draught Surveying
Specialist draught-survey calculations, techniques and procedures.
FAQ
Draught Surveying FAQ
What is a draught survey?
A draught survey determines cargo weight from the change in vessel displacement between two survey conditions, after accounting for ballast, fuel, fresh water and other variable weights.
Why is draught surveying used for bulk cargo?
It allows large shipload quantities to be determined from vessel hydrostatics when direct weighing of the complete cargo may not be practical.
What information is needed for a draught survey?
Typical inputs include draught readings, water density, hydrostatic data, ballast quantities, consumables and other variable vessel weights.
What is dock-water density correction?
It adjusts displacement where the density of the water around the vessel differs from the reference density used in the ship's hydrostatic information.
What can cause draught survey errors?
Poor readings, vessel movement, density error, uncertain tank quantities, incorrect hydrostatic data, unusual trim/list and calculation mistakes can all affect results.
Is draught surveying the same as cargo weighing?
It is an indirect weight-determination method based on displacement rather than a direct scale measurement.
Does the IMSBC Code tell surveyors how to calculate a draught survey?
The IMSBC Code primarily addresses the safe carriage of solid bulk cargoes. Draught surveying is a separate commercial quantity-determination activity.
Can draught surveying be studied online?
Yes. IMT currently lists Expert in Draught Surveying as an online Advanced Diploma Cargo Surveying programme with 52 hours of study.
What is included in the IMT draught-survey course?
The current course combines Marine Cargo Survey Practices, Essential Law, Technical Report Writing and the specialist Expert in Draught Surveying module.
What should I study after draught surveying?
Useful related courses include Bunker Surveying, Dry Bulk Cargo Survey, General Cargo Inspection and broader Cargo Surveying training.
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