PURPOSE: To reduce resistance and improve maneuverability by setting the rear edge of a keel line close to the lower area of a propeller boss and forming a ship bottom into shallow V form with the front half and the rear half of the keel line.

CONSTITUTION: The front-half keel line 7' and the rear-half keel line 7" of a small-sized dragnet fishing vessel on which an engine is installed almost at the center of the hull are set in a shallow V' form at the centeral part of the hull, and the rear edge of the rear-half keel line 7" is set close to the lower area of a propeller boss 3, and the front edge is set on the straight line in contact with the keel line of an engine room at the centeral part. As need of installing the projection part such as the box keel in the ship bottom part in the conventional is obviated, the resistance on the hull can be reduced, and the excess direction holding performance of the ship can be made proper, and maneuverability of the ship can be improved.