In Figs 16 and 17 the experimental results of Ct , Cr and Cd for the double fixed FB are presented. The influence of S/L
(S = the spacing between the two FBs) on the performance of the double FB is shown. The transmission coefficient decreases
with an increase of S/L from 0.2 to 1.4, where a resonance point is observed after which the transmission coefficient increases for both wave heights. The resonance of the water masses between the two breakwaters seems to be an important parameter in the efficiency of the specific configuration and a wider range, in terms of wave period, of experimental tests would reveal more resonance points.
In Fig. 17 the comparison of the single and double FB indicates that the latter configuration is generally much more efficient. The double FB configuration presents the lowest transmission coefficient, Ct = 0.12, for B/L equal to approximately 0.3. Reflection and dissipation are generally higher for the double FB case.