PURPOSE: To improve a readiness to adapt and a target detection capacity in operation by providing a wood assembly type straightening hood made up of sheets of wood plate materials laminated.

CONSTITUTION: A transmitter/receiver 2 and other devices are mounted in a sonar dome 1 provided on the bottom of a ship. For example, a stainless base mounting metal 5 is fixed on the underside of a dome support member 4 set on the ship bottom. Then, a ring-shaped base 10 is fixed on the undersurface of a lower horizontal plate 7 of the metal and a roughly hemispherical wooden straightening hood 12 made of white cedar or the like is fastened on the underside of the base 10 to close an opening 11 through a hood mounting metal 13. The hood 12 is a laminate of hemispherical shell bodies in four layers and each of the shell bodies are formed into a roughly hemispherical shape by joining side end faces of a plurality of plate materials with such a shape as given by cutting the surface of a hemisphere with a plurality of planes passing one diameter to be made hemispherical. A wood laminate type dome 1 is good at a property of transmitting sound waves and moreover, high in rigidity thereby enabling common use for navigation and searching detection.