Draft & Trim Calculator
Calculate changes in ship's draft and trim due to loading, discharging, or shifting weights.
Initial Drafts
Ship Particulars
Weight Operations
Weight 1: Weight 1
**Note:** This calculator provides an estimation. LCF, LCG are considered from midship (+ve if aft of midship). TCG is from centerline (+ve if starboard). Actual results may vary. Always consult official stability booklet and loading computer. Visuals are indicative.
About Draft & Trim Calculator
Essential Vessel Stability Management
Maintaining the correct draft and trim is vital for a ship's safety, propulsion efficiency, and maneuverability. This calculator allows Deck Officers to predict how the ship's waterline will change after any cargo or ballast operation, helping to prevent grounding and ensure the vessel remains within its "Load Line" limits.
Calculation Methodology
1. Parallel Sinkage/Rise (cm):
Sinkage = Net Weight (T) / TPC
2. Change of Trim (cm):
ΔTrim = (Weight × (LCG - LCF)) / MCTc
3. List (Transverse Stability):
Heeling Moment = Weight × TCG
User Definitions
- TPC (Tonnes per cm): The weight required to sink the ship by exactly 1 cm.
- MCTc (Moment to Change Trim 1cm): The trimming moment required to change the total trim by 1 cm.
- LCF (Center of Flotation): The pivot point of the ship's waterplane. All trimming moments are calculated relative to this point.
- LCG/TCG: The Longitudinal and Transverse centers of gravity of the added/removed weight.
Practical Considerations
These calculations assume a "rigid ship" and small angles of trim. For heavy lists or extreme trim conditions, hydrostatic data from the ship's official Stability Booklet must be consulted. Always verify physical draft marks before and after operations.