Marine, Shipbuilding & Boat Manufacturing worked example

Vessel Displacement Estimate with waterline length of 30 m: a worked example

This scenario runs the vessel displacement estimate calculation on the strong side: waterline length of 30 m, with every other input held at its documented default. Use it during preliminary design to estimate displacement before weight buildups are complete, for early powering estimates and hull structural scantling checks.

The inputs for this scenario

  • Waterline length (LWL): 30 m (raised for this scenario; the documented default is 12)
  • Beam at waterline (BWL): 3.8 m (unchanged)
  • Design draft (T): 1.1 m (unchanged)
  • Block coefficient (Cb): 0.48 factor (unchanged)

Working through the calculation

  • Applying the documented formula (Displaced volume = LWL x BWL x draft x block coefficient) to the inputs above produces each figure below.
  • At this operating point the engine returns 10,364 kg for displacement (saltwater), the number this scenario is built around.
  • At this operating point the engine returns 114 kg for displaced volume.
  • At this operating point the engine returns 10,250 kg for water density factor.
  • At this operating point the engine returns 1.1 % for block coefficient applied.

How this compares with the baseline

  • Against the tool's baseline example, where waterline length sits at 12 m and the headline result is 4,145 kg, this scenario comes in 150% above the baseline at 10,364 kg.
  • Use it in concept and preliminary design to check target weight against hull dimensions, or to back out a block coefficient from a known displacement. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Displacement (saltwater): 10,364 kg (headline result)
  • Displaced volume: 114 kg
  • Water density factor: 10,250 kg
  • Block coefficient applied: 1.1 %

Run it with your numbers

  • Every input above is editable in the live Vessel Displacement Estimate calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.