Ship Trim, Draft Change & Longitudinal Balance Tool

Ship Trim, Draft Change & Longitudinal Balance Calculator | ShipUniverse

Load • Discharge • Shift • TPC • MCT 1 cm • LCF • Forward/Aft Draft • Target Trim • Hydrostatic Interpolation

Ship Trim, Draft Change & Longitudinal Balance Tool

Calculate how cargo, ballast, bunkers, stores or equipment movements change displacement, mean draft, trimming moment and forward/aft drafts. Use vessel-specific TPC, MCT 1 cm and LCF data, solve target trim by shifting or loading ballast, interpolate hydrostatic-table rows, and screen final drafts against owner-entered operational limits.

Initial Vessel Condition

Vessel type

Length between perpendiculars (LBP)m.

Initial forward draftm at the calculation reference.

Initial aft draftm at the calculation reference.

Hydrostatic data source

Initial displacementtonnes.

Hydrostatic Inputs

Use the vessel's approved hydrostatic particulars at, or close to, the operating draft. TPC, MCT 1 cm and LCF vary with draft and hull form.

TPCtonnes per centimetre immersion.

MCT 1 cmtonne-metres per centimetre trim.

LCF from midshipsm; positive aft, negative forward.

Hydrostatic-row mean draftm.

Single Weight Operation

Operation

Weighttonnes.

Load / discharge position xm from midships, + aft / − forward.

Shift FROM position xm from midships.

Shift TO position xm from midships.

Description

Advanced Cargo / Ballast / Bunker Movement Register

Load/discharge rows change displacement and trim. Shift rows change trim only. Positions are always metres from midships, positive aft.

Description	Operation	Weight t	Position x m	From x m	To x m

Hydrostatic Table Interpolation

Enter adjacent rows from the vessel's hydrostatic table. The tool linearly interpolates displacement, TPC, MCT 1 cm and LCF at the initial arithmetic mean draft.

Mean draft m	Displacement t	TPC t/cm	MCT 1cm tm/cm	LCF x m (+aft)

Draft & Trim Operating Limits

Enter actual load-line, berth, propeller-immersion, stability-booklet, terminal or company limits applicable to this condition.

Maximum forward draftm; 0 disables.

Maximum aft draftm; 0 disables.

Maximum arithmetic mean draftm; 0 disables.

Minimum aft draft / propeller-immersion limitm; 0 disables.

Maximum trim by sternm; 0 disables.

Maximum trim by bowm magnitude; 0 disables.

Target Trim Solver

Solve either the distance an existing weight must shift, or the signed ballast/cargo weight required at a known longitudinal position.

Target final trimm; positive by stern, negative by bow.

Movable weight for shift solvertonnes.

Ballast / cargo solver position xm from midships.

Target solver use

Operational Readiness

Approved hydrostatic data usedTPC, MCT 1 cm and LCF correspond to the vessel and draft range. Weight quantities / tank volumes verifiedCargo, ballast, bunkers and stores quantities are credible. Longitudinal positions / tank LCGs verifiedPositions come from vessel capacity/loading information. Approved loading computer to be checkedFinal stability and longitudinal strength remain separate checks. Load-line / berth / UKC limits confirmedFinal drafts will be checked against actual voyage and port limits. Free-surface effects handled separatelyThis trim tool does not calculate GM or free-surface correction. Shear force / bending moment checked separatelyGood trim can coexist with unacceptable hull loading. Loading/unloading sequence reviewedIntermediate conditions may govern.

Calculation limitation: This tool uses the traditional small-change TPC / MCT 1 cm / LCF method. Large weight changes, large trim, unusual hull forms, non-linear hydrostatics, hog/sag, density effects, draft-mark corrections and damage conditions require the approved vessel loading/stability system or naval-architect calculation.

Regulatory / approval context: IMO's 2008 Intact Stability Code requires stability information suitable for the Master, and IACS UR L5 Rev.4 remains the current unified requirement for onboard computers used for stability calculations. For applicable bulk carriers, IACS UR S1A continues to require approved loading information/instruments addressing loading conditions and hull-girder limits. This calculator is a planning and cross-check aid only; it does not replace the ship's approved trim/stability booklet, loading instrument, loading manual, strength limits, damage-stability information or load-line requirements.

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