PURPOSE: To cause a dynamical neutral shaft line at a gunnel material section to incline toward the inboard and to reinforce the rigidity of the gunnel material, by a method wherein, in a small-sized ship made of fiber reinforced plastic, an inboard edge part of a gunnel material is formed in a longer length than that of an outboard side edge.

CONSTITUTION: A section of a gunnel material 14 is formed in U-shape whose lower part is open, and an inboard side edge part 5 is formed in a longer length than that of an outboard side edge part 16. The inboard side edge part 15 of the gunnel material 14 is staged (19), and a core material 20, made of lauan material, is adhered at a part below the staged part 19 and is wrapped with a lining 21, made of FRP, in conjuction with the inboard side edge part 15. The outboard side edge part 16 of the gunnel material 14 is fastened on a ship 11 through a fender beam 24 by a bolt or other means. This constitution causes the improvement of the rigidity of the gunnel material through the inclination of a dynamical neutral shaft line at a section of the gunnel material toward the inboard side as shown in a mark 17.