a breakwater includes two horizontal tubes as buoyant members connected to one another , their cross - sections representing vertices of a triangle , whose legs are interconnecting struts . a perforated , submerged , ballast tube forms the third vertex . wave motion is perpendicular to the length of the float tubes tethered to an anchor at the sea floor . a lead float tube rises in response to an approaching wave , often cutting off the wave crest , while a trailing float tube rises less and later as the wave passes . asynchronous rising and falling of the leading and trailing , floating , top tubes rocks the breakwater , redirecting and dissipating wave momentum , energy , and water volume by rotating the assembly , thrashing the water .