Ship Measurement Course

Lesson 1 • History and Purpose of Tonnage

Traces tonnage from medieval wine-cask counting to modern gross tonnage. Grounds all subsequent measurement concepts in practical commercial and regulatory necessity.

Lesson 2 • Classification Societies and Surveyors

Explains how classification societies delegate measurement authority and how surveyors operate within that system. Sets professional context for the course.

Lesson 3 • International Regulatory Framework

Surveys the international conventions and flag-state obligations that mandate ship measurement. Connects regulatory compliance to surveyor responsibilities.

Lesson 1 • Principal Dimensions of a Vessel

Covers length overall, length between perpendiculars, breadth, depth, and draught. These dimensions are the direct inputs to all tonnage and stability calculations.

Lesson 2 • Decks, Spaces, and Compartments

Defines freeboard deck, superstructures, deckhouses, and enclosed spaces. Accurate space identification is prerequisite to gross and net tonnage computation.

Lesson 3 • Hull Form Coefficients

Introduces block, prismatic, midship, and waterplane area coefficients. Students learn how these ratios characterise hull fullness and affect volume calculations.

Lesson 1 • Electronic Distance Measurement

Introduces laser distance meters, total stations, and ultrasonic gauges. Electronic tools accelerate data collection and reduce human error in large spaces.

Lesson 2 • Traditional Measuring Instruments

Covers steel tapes, measuring rods, plumb bobs, and ullage tapes. Mastery of traditional tools ensures accuracy when digital equipment is unavailable.

Lesson 3 • Draught Gauges and Inclinometers

Explains draught reading at marks, electronic draught gauges, and inclinometers for trim and heel. These instruments feed directly into displacement and freeboard assessments.

Lesson 1 • GT Calculation Worked Examples

Applies the full GT procedure to cargo ship, tanker, and passenger vessel case studies. Worked examples consolidate formula knowledge into professional practice.

Lesson 2 • GT Verification and Certification

Covers surveyor verification steps, flag-state submission, and issuance of the International Tonnage Certificate. Connects calculation output to official documentation.

Lesson 3 • Measuring and Summing Enclosed Spaces

Provides systematic methods for measuring each enclosed space and aggregating volumes. Accurate space summation is the most labour-intensive step in GT calculation.

Lesson 4 • Excluded and Exempted Spaces

Details which spaces are excluded from V by convention rule and which may be exempted by application. Misclassification directly inflates or deflates GT.

Lesson 1 • Net Tonnage Formula and Logic

Explains the NT formula components: cargo volume, passenger spaces, draught ratio, and GT cap. Students see how NT reflects earning capacity rather than total volume.

Lesson 2 • Passenger Space Calculations

Covers counting certified passengers, applying the per-passenger volume factor, and combining with cargo NT. Passenger vessels require a distinct calculation branch.

Lesson 3 • Measuring Cargo Spaces

Details measurement of holds, tanks, and ro-ro decks for NT purposes. Cargo space measurement differs from GT space measurement in scope and method.

Lesson 1 • Density and Salinity Corrections

Applies dock water density corrections using a hydrometer and salinity tables. Density errors are amongst the most common sources of deadweight inaccuracy.

Lesson 2 • Hydrostatic Tables and Curves

Explains how to read and interpolate hydrostatic tables for displacement, TPC, LCB, and KM. Hydrostatic data is the backbone of every displacement calculation.

Lesson 3 • Draught Survey Procedure

Provides the six-draught reading sequence, trim correction, and mean draught derivation. A rigorous draught survey procedure minimises cargo quantity disputes.

Lesson 4 • Constant and Deductible Items

Identifies the ship's constant, ballast, fuel, fresh water, and stores as deductibles. Accurate deduction of these items converts displacement to cargo deadweight.

Lesson 1 • Tabular Freeboard Determination

Walks through the tabular freeboard lookup by ship type and length, then applies corrections. The tabular method is the starting point for all freeboard assignments.

Lesson 2 • Load Line Mark Placement and Verification

Specifies the geometry, position, and painting requirements for the load line disc and lines. Correct mark placement is verified by the surveyor before certificate issuance.

Lesson 3 • Seasonal and Zone Allowances

Explains tropical, summer, winter, and fresh water zones and their freeboard adjustments. Zone allowances directly affect the maximum permissible draught in each region.

Lesson 4 • Structural Conditions for Freeboard

Reviews hatch cover strength, freeing port areas, and superstructure integrity as freeboard prerequisites. Structural deficiencies can invalidate a freeboard assignment.

Lesson 1 • Measurement of Special Vessel Types

Addresses offshore units, dredgers, barges, and high-speed craft where standard rules require adaptation. Special vessel types demand judgment beyond routine formula application.

Lesson 2 • Integrated Tonnage and Freeboard Survey

Combines GT, NT, deadweight, and freeboard surveys into a single vessel visit workflow. Integration reduces vessel downtime and ensures data consistency across certificates.

Lesson 3 • Measurement Disputes and Expert Evidence

Prepares students to defend measurement results in commercial disputes and arbitration. Expert evidence skills protect the surveyor's professional credibility.

Lesson 4 • Re-measurement After Structural Alterations

Identifies alterations that trigger re-measurement, documents changes, and recalculates affected tonnage figures. Structural changes are the most common cause of certificate amendments.