ERDC/CHL CHETN-III-66
June 2003
0.36 ft). Maximum horizontal and vertical centroid movements, respectively, for the west
breakwater were 0.64 and 0.18 m (2.1 and 0.6 ft), while average movements were 0.11 and 0.06 m
(0.37 and 0.21 ft) in the horizontal and vertical directions. Changes in rotation angles varied from
0.0 to 17.32 deg for the west breakwater with an average of 2.02 deg. Even though some units had
moved 0.91 to 1.5 m (3 to 5 ft) on the breakwaters, visual observations indicated they had not broken
and continued to be functional. A broken armor unit survey conducted during August 2001 revealed
29 broken or cracked armor units above the waterline on the east breakwater and 58 on the west
structure. Of the 29 broken units on the east breakwater, 19 were 5,443.10-kg (6-ton) dolosse, two
were 8,164.66-kg (9-ton) tribars, four were 27,215.54-kg (30-ton) dolos, and four were 31,751.47-kg
(35-ton) tribars. Of the 58 broken units on the west breakwater, four were 5,896.70-kg (6.5-ton)
tribars, one was a 9,979.03-kg (11-ton) tribar, 16 were 17,236.51-kg (19-ton) tribars, 18 were
18,143.64-kg (20-ton) dolos, 11 were 27,215.54-kg (30-ton) dolos, five were 29,937.1-kg (33-ton)
tetrapods, and three were 31,751.47-kg (35-ton) tribars. Concentrations of broken armor units were
identified on various areas of the breakwaters. Considering the types of breaks for the 52 broken
dolosse on both structures, 75 percent had shank-fluke breaks, 16 percent had fluke-shank breaks,
9 percent had mid-shank breaks. Of the dolos breaks recorded, 78 percent were straight and
22 percent were angled. Considering the types of breaks for the 35 tribars and tetrapods on the
breakwaters, 89 percent included units with breaks through the center sections where one or more
legs had separated, and 11 percent had just portions of a leg broken off the unit. These data establish
a base from which to evaluate future breakage in subsequent surveys. Even though some breakage
has occurred, the structures appeared to be in good condition overall.
LAUPAHOEHOE POINT BOAT-LAUNCHING FACILITY BREAKWATER, HI:
Laupahoehoe Point is located on the northeast coast of the island of Hawaii. A park and boat
launching facility is situated in the area. To protect the boat launch, a 60.96-m- (200-ft-) long
breakwater was constructed in 1988. Base conditions for the breakwater were established in 1992
(Markle and Boc 1994) under the "Periodic Inspections" work unit of the MCNP Program. The
structure was revisited in 2001 (Bottin and Meyers 2002b).
The breakwater (Figure 4) is
armored with 30-ton dolosse and the
crest is stabilized with a concrete rib
cap. The crest elevation of the
structure is +3.66 m (+12 ft). Side
slopes along the sea side and the
breakwater head vary from 1V:2H
to 1V:2.5H and slopes on the harbor
side of the structure vary from
1V:1.5H to 1V:2H.
During the initial photogrammetric
survey of November 1992, selected
armor units were targeted (three
targets each) and precise positions
of these units were obtained.
Centroid data positions and orien-
tations of the targeted armor units
Figure 4. Laupahoehoe breakwater
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