Wave heights so determined should then be checked against the maximum possible breaking wave
at the design water level. This should be evaluated using Figure 18 and the depth at the toe of the
structure, or if appropriate, the minimum depth offshore from the structure. With the design water depth
at the toe of the structure ds ; the wave period, T; and the fronting bottom slope, m; the breaker height Hb, can
be found as a function of ds. For instance, if ds = 3.0 feet, m = 1:33, and T = 4.0 seconds ds/gT2 =
0.00582, and Hb,/ds = 0.98; therefore, Hb = 3.0 x 0.98 = 2 (say 3.0) feet. T. Minimum depth along fetch line
is near Cedar Point where the depth is 1 foot at MLW, and 3.l feet under the design water level. This would
not control for this case (it is greater than ds), but it should be checked in every instance. Fetch line (2) does
not cross similar shoal areas.
If the wind-driven wave height was 3.5 feet, it should not be used for design because only a 3.0-foot
wave can be supported based on the available minimum depth at the structure. The final design wave height,
therefore, should be 2.9 (3.0) feet in this case. To restate the rule, the design wave height should be the
lesser of the maximum wind-generated wave along the fetch, or the maximum possible breaking wave at the
structure or at points offshore.
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