Turfblocks or Monoslabs. Turfblocks are patented units designed for hand placement on a filter
with their long axes parallel to the shoreline (Figure 25). Each block measures 16 x 24 x 4.5 inches and
weighs approximately 100 pounds. Field installations have not yielded conclusive results, but their
performance should be similar to that of Jumbo blocks. Their thin, flat shape requires a good, stable
foundation, as any differential settlement beneath the blocks makes them susceptible to overturning under
wave action.
Nami Ring. The Nami Ring is a patented block shaped 'like a short section of concrete pipe, 2.5
feet in diameter by 1 foot high, and weighing 240 pounds. The rings are placed on a slope over filter
cloth, performing best when they are 3olned with tie rods. Sand or gravel caught in the wave turbulence
tends to be deposited inside or in voids between adjacent rings, adding to the stability of the section and
protecting the filter cloth. Because of their shape, Nami Rings are susceptible to severe abrasion and
damage by water-borne cobbles and, therefore, should be used primarily on sandy shores.
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