The longitudinal structure is needed to hold the boat, especially in sagging and hogging conditions. Modifying a longitudinal system using laminating steel and fiber is required to increase strength and reduce weight. This study uses a 7.8 m ship modified from conventional to hybrid construction. The finite element method compared the conventional and hybrid ship structures under sagging and hogging conditions to evaluate ship strength. In sagging conditions, the maximum stress in conventional boats is 16.68 MPa, reduced up to 13.65 MPa in hybrid boats. In hogging condition indicate that conventional has maximum stress is 11.18, which is higher than in conventional structure, as much as 10.38 MPa. The keel stress distribution in a couple of conditions of sagging and hogging indicates that the hybrid structure has lower stress than conventional vessels. The simulation shows that a longitudinal hybrid frame makes the ship stiffer in sagging and hogging conditions. The weight of conventional and hybrid boats is similar and affordable to more developing hybrid ships.