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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Coeficiente prismático (Cp)
Enquanto o coeficiente de bloco mede o 'enchimento' global, o coeficiente prismático Cp = ∇/(Am·L) descreve como o volume se distribui ao longo do casco, comparando-o a um prisma com a área da seção mestra constante de proa a popa. Cp baixo (~0,55) concentra o volume no meio e afina as pontas — ótimo para baixas velocidades, menos resistência de onda. Cp alto (~0,65+) empurra volume para as extremidades — melhor em altas velocidades, onde os corpos de proa e popa precisam de volume para sustentar o trem de ondas. É um parâmetro-chave na otimização da resistência ao avanço. Informe o volume deslocado, a área da seção mestra e o comprimento.
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Block Coefficient (Cb)
Compute a ship's block coefficient (Cb), Cb = ∇/(L·B·T), the ratio of the displaced (carene) volume to the enclosing box (length × beam × draft). It measures how 'full' the hull is: slow cargo ships have a high Cb (~0.8); fast, fine vessels a low Cb (~0.5). It is one of the central parameters of naval architecture. Enter the displaced volume, the length, the beam and the draft.
Hull Wetted Surface
Estimate the hull's wetted surface area by Denny's formula, S = 1.7·L·T + ∇/T, from the length (L), the draft (T) and the displaced volume (∇). The wetted surface drives frictional resistance — the largest share of drag at low speeds — and underlies power calculation and the area to be coated with antifouling paint. Enter the length, the draft and the displaced volume.
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.
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