LW33 / ASSUMPTION SENSITIVITY

Which results hold up?

Compare loading, assumed centre of gravity and sea states. Each case uses the same model at two time steps.

Select a case to inspect its paired motion traces
Case	Speed	Mass	CG shift / VCG	Sea	Finding

Blue · 1/240 sBronze dashed · 1/480 s

Chart shows 2 Hz samples. Stops truncate the trace; nothing beyond the stop is predicted. Summary maxima use 20 Hz samples, so sharp peaks may be missed. Rise is measured at each assumed CG relative to its own resting position.

Protocol and interpretation

Calm-water settling screen: final 10-second trim range <0.05°, rise range <1 mm, vertical force imbalance <0.5%, pitch moment <10 Nm at both time steps. Mean trim must differ by <0.05° and mean rise by <1 mm. Wave screen: full-run RMS differences <0.5° pitch and roll, and <50 mm heave, with both 60-second runs completed. A wave result is not expected to settle.

CG shift is relative to the model's assumed longitudinal reference, positive forward. VCG is height above the historical keel. These are exploratory ranges, not measured uncertainty bands. The 2,750 mm estimate has no confirmed datum and is not treated as a measured CG. Fuel, people and cargo positions are not inferred from total mass.

No new CFD solution or browser/device visual test is represented here. The model still omits full drive forces, engine power balance, added mass, horizontal wave orbital velocity and breaking waves. Next physical inputs: marked CG and drive drawing, confirmed hull closures, weight inventory and measured bow/stern drafts; then sea-trial calibration.