Hull form improvements of a fishing vessel fitted with non-protruding bow bulbs are presented in this paper. Non-protruding bulbs are developed by Calisal et al., who call them side bulbs, to overcome the situation that classical protruding bulbs are not suitable for the operation of seiner nets. In the present work, a fishing vessel used off the coast of Canadian pacific is improved under several design constraints by means of nonlinear programming, in which the stability constraint is included. In order to verify these improvements, towing tests and wave analyses are carried out for models of improved hull forms. In the process of these experimental verifications, a simplified estimation method of resistance is also shown with respect to improved hull forms, which is based on the correction of thin ship theory by using the resistance data of the parent hull form.