Figure 6. Concrete rib cap on crest of Ofu Harbor breakwater 
The 510-kg (1,125-Ib) concrete units were used as an underlayer for the 2,270-kg 
(2.5-ton) units. They also were used as an underlayer for the tribars around the 
breakwater head since the 1,635-kg (1.8-ton) “swiss cheese blocks” could not be 
placed in this area around the relatively tight radius. The dimensions of the 
Chapter 1 
Introduction 
