Sound emitter - Stacked array
Alternative terms: Stacked array (U.S.A.), Vertical stack (G.B.)
An assembly of sound emitters, mounted vertically one above the other and so spaced and excited as to concentrate their power in the horizontal direction.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
centre of gravity
Centre of buoyancy
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM