Strip theory

Strip theory predicts ship motions by slicing the hull into transverse strips, solving the two-dimensional added-mass and damping of each section (often via Lewis-form conformal mapping), then integrating along the length. The Salvesen-Tuck-Faltinsen formulation is the classic version. It is fast and accurate for slender hulls in moderate seas and head or following waves, and it remains the workhorse for first-pass seakeeping before 3D panel or RANS analysis.