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MARINE / Marine Trim Calculator

Marine Trim Calculator

Identify trim by stern, trim by bow or even keel; optionally calculate gradient and angle using a reference length.

Inputs

Updates as you type

Results

Trim · AFT − FWD

0.7m
Results
Forward draft7.8 m
Aft draft8.5 m
Mean draft8.15 m
Trim conditionTrim by Stern
FWD · BowAFT · SternDirection only · not to scale

Overview

Identify trim by stern, trim by bow or even keel; optionally calculate gradient and angle using a reference length.

Formula 

Trim = TAFT − TFWD
Tmean = (TFWD + TAFT)/2
g = Trim/Lreference
θ = atan(g) × 180/π
For small angles: θ [rad] ≈ Trim/Lreference

Example

FWD 7.8 m and AFT 8.5 m give +0.7 m, or trim by stern. With a 100 m reference length, the gradient is 7 mm/m and the angle is approximately 0.401°.

How to use

  1. Check the units, enter the required values and select the available calculation options.
  2. Results update immediately. Correct any highlighted input before using the result.
  3. Choose display precision, copy the result or share the current inputs. Reset restores the example values.

Engineering notes

  • Use a reference length consistent with the draft measurement positions. Leave it blank if only the draft difference is needed.
  • The ship diagram exaggerates direction and is not to scale. Hydrostatic, stability, hull deformation and draft-mark corrections are excluded.

Frequently asked questions FAQ

What if another document uses the opposite sign?

This site uses AFT − FWD. A document using FWD − AFT has the opposite sign. Record the definition when transferring results.

Does display precision change the calculation?

No. Rounding is applied only to displayed results, not intermediate calculations. Small nonzero values use scientific notation. Consider the precision of the original measurements when interpreting results.

KEEP WORKING

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