The paper presents the first 3D fully Lagrangian meshfree projection-based hydroelastic solver for fluid-structure interactions (FSI) encountered in ocean engineering. The fluid model is based on an enhanced version of a projection-based SPH, namely, Incompressible SPH or ISPH; the structure model is based on SPH approximations of conservations of linear and angular momenta. The fluid-structure coupling is achieved by incorporating a so-called FSA or Fluid-Structure Acceleration-based scheme to ensure satisfaction of fluid-structure interface boundary conditions. Validations are performed through both classical benchmark test cases as well as engineering ones. Stable and acceptable results are achieved without inclusion of any artificial numerical stabilizers that often require tuning.