Deflection is the degree when the structural element is displaced due to a load. Deflection is measured by different methods like Castigliano’s method, Macaulay's method, direct integration etc. When it comes to a simple construction, beams which play a vital role are selected considering the deflection amongst many other factors. And the deflection is calculated with the following formula:

    fB = F·L3 / (3·E·I)
    φB = F·L2 / (2·E·I)

Here,

F = force acting on the tip of the beam
L = length of the beam (span)
E = modulus of elasticity
I = area moment of inertia

This was deflection in engineering terms. When it comes to shipping sector for e.g.: hull deflection of damaged warships, it is caused due to the loss of bending rigidity. Deflection of hull includes bending deflection and shearing deflection where the shearing deflection is usually ignored focusing on the deflections caused above and below the waterline. Further using Vlasov’s method, the buoyancy curves of damaged hull in wave and wave bending moments and shearing forces are taken into account along with damaged hull deflection when under hogging and sagging condition hence verifying the longitudinal strength of damaged sections.