In the field of underwater acoustics, the boundary element method is usually used to model acoustic radiation or scattering from an immersed structure impinged by an acoustic wave. The EQI boundary element code uses Helmholtz integral equation. The Sommerfeld radiation condition is implicitly included in the formulation, and the pressure field in the surrounding fluid is evaluated from the mesh restricted to the surface of the body. At some frequencies called irregular frequencies, this integral formulation presents an infinite number of solutions. This problem is solved with the help of the Jones method: The integral equations system is overdetermined by null-field equations. For a multifrequency analysis, integral equations matrix assembling is very computation time consuming. A new boundary element algorithm based upon a frequency interpolation is proposed. It is adapted to quadratic isoparametric discretization for any geometry. This technique is original for two reasons: the automation of its utilization between 0 Hz and the top frequency of the spectrum; its adaptation to axisymmetrical problems by decomposition of circular integration surfaces. This algorithm allows an important saving of computation time which increases with the size of the problem without loss of precision.