Displacement of a Deflected Ship Hull

Relevant approximations based on permanent waterplane characteristics are summarized for a more accurate assessment of the effects of longitudinal deflections of an elastic ship's hull on drafts and displacement during marine surveys of merchant ships. The possibility of a different practice for placement of draft marks on a ship's sides, ensuring the same precision in displacement assessment of a deflected and trimmed hull by only two draft observations, is investigated by employing the waterplane properties. Correction factors for conventional ships, based on the waterline coefficient for changes of hydrostatic load, arising due to hull deflections, are also summarized. Example results are demonstrated on a Croatian-built bulk carrier.