Reserve Buoyancy
Compute a vessel's reserve buoyancy, R = (total_volume − submerged_volume)/submerged_volume·100%, the percentage of watertight volume above the waterline relative to the submerged volume. It is the safety margin against sinking: the larger it is, the more cargo or flooding the hull tolerates before submerging. It defines the freeboard and the damage survivability. Enter the total watertight volume and the submerged volume.
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Reserva de flutuabilidade
Um navio flutua porque desloca um peso de água igual ao seu — mas o que o salva quando embarca água ou carga é a reserva de flutuabilidade: o volume estanque que ainda está acima da linha d'água, pronto para entrar em ação. Calcula-se R = (Volume_total − Volume_submerso)/Volume_submerso·100%, comparando o volume seco com o já submerso. Quanto maior a reserva, mais carga ou alagamento o casco tolera antes de afundar — é a margem que separa um barco seguro de um que vira com a primeira onda na borda. Ela define o bordo livre (regido pela linha de Plimsoll) e a capacidade de sobreviver a avarias com compartimentos alagados. Informe o volume total estanque e o volume submerso.
Related Tools
Cylindrical Shell MAWP
Calculate the maximum allowable working pressure (MAWP) of a pressure-vessel cylindrical shell, MAWP = (S·E·t) ÷ (r + 0.6·t), from the allowable stress S (MPa), the joint efficiency E, the available thickness t (mm, corrosion-deducted) and the internal radius r (mm). The MAWP is the MAXIMUM pressure a vessel can safely operate at the top, in the operating position, at the design temperature — one of a pressure vessel's most important numbers, stamped on its nameplate. It is the INVERSE of the thickness calculation: given the REAL available thickness (supplied, minus corrosion suffered), the maximum pressure it withstands is computed. MAWP is fundamental for several reasons: it sets the SAFETY-VALVE setting (which must open before pressure reaches MAWP, protecting the vessel from overpressure — the cause of explosions); it establishes the vessel's operating limit; and, recomputed periodically with the REMAINING thickness (measured by ultrasound at inspection, decreasing with corrosion), it monitors the vessel's 'health' over life — when MAWP drops below the operating pressure, the vessel must be repaired or retired. Each component (shell, heads) has a MAWP, and the vessel's is the smallest (the weakest component). Enter the allowable stress, efficiency, thickness and radius.
Hull Speed
Compute the hull speed of a displacement vessel, V ≈ 2.43·√(LWL), in knots, from the waterline length (LWL, in meters). It is the theoretical limit of a hull's economical speed: as the boat approaches it, it gets trapped in its own bow wave and the required power soars. That is why sailboats and displacement craft rarely exceed it. Enter the waterline length.
Prismatic Coefficient (Cp)
Compute a hull's prismatic coefficient (Cp), Cp = ∇/(Am·L), the ratio of the displaced volume to that of a prism with the midship section area (Am) along the whole length. It indicates how volume is distributed lengthwise: a low Cp concentrates volume amidships (good for low speeds), a high Cp pushes it to the ends (better at high speeds). It is decisive in resistance design. Enter the displaced volume, the midship section area and the length.
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