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.
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Área molhada do casco
A superfície molhada — toda a área do casco em contato com a água — é o que gera a resistência friccional, a maior parcela do arrasto em velocidades baixas e médias. Calculá-la exatamente exige a geometria 3D do casco, mas a fórmula de Denny dá uma boa estimativa a partir de três números: S = 1,7·L·T + ∇/T, combinando a área dos costados (≈ comprimento × calado) com um termo de fundo ligado ao volume. O resultado alimenta o cálculo de potência (quanto maior a área, mais atrito) e estima a quantidade de tinta anti-incrustante para a obra viva. Informe o comprimento, o calado e o volume deslocado.
Related Tools
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.
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.
Bolt Tensile Stress
Calculate the tensile stress in a bolt, σ = F_b ÷ A_t, from the total bolt tensile force F_b (N) and the tensile stress area A_t (mm²). It is the basic strength check of a tensioned bolt: the acting stress (force over resisting area) must be below the material strength with a safety margin. The force F_b is the total load the bolt carries — in a preloaded joint, the preload plus the fraction of external load reaching the bolt (F_i + C·P). The resulting stress is compared with the proof strength S_p (the limit up to which the bolt can be loaded without permanent deformation — typically 85-90% of yield) or the ultimate strength, per the criterion. The bolt strength class (marked on the head: 8.8, 10.9, 12.9 metric; or SAE grades 2, 5, 8) sets these allowable stresses — a class 8.8 bolt has a proof strength of 580-600 MPa, a 12.9 reaches ~970 MPa. Verifying σ does not exceed the allowable, considering preload and service load, is essential: overloaded bolts yield (losing preload) or break. With the fatigue and separation checks, it defines the tensioned joint's safety. Enter the total bolt force and the tensile area.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.