A CONVERSATION ABOUT WAVE ATTENUATORS

1 Apr, 2017

 

Floating   wave   attenuators are a recurring subject in Marina Dock Age. Jack Cox wrote about them in “Revisiting Marina Design Standards” in the January/February 2017 issue. This month we present a wide-ranging dialogue between Cox and another experienced engineer, Craig Funston, focused on the question, “What basic knowledge should a marina developer have about wave attenuators?”

Let’s meet our engineers for this discussion. Jack Cox is a principal of SmithGroup JJR. Cox spoke to us from his office in Madison, Wisconsin. Craig Funston is principal of Redpoint Structures in Bellingham, Washington. Both have long résumés with impressive marina design projects, including dozens of wave attenuators, and both are respected experts in the field.

Marina Dock Age: Do you see any trends in developers’ criteria for tranquility inside a marina? What do they consider an acceptable wave environment?

Jack Cox: Owners used to tell me that if their marina was as calm as the competition, it’s calm enough. We’re not hearing that anymore. Marinas are becoming social neighborhoods and people like to spend time on their boats in the slips. Boaters used to be alarmed when sailboats rocked and their shrouds got tangled. Now they’re upset if a guest spills a martini while watching the sunset.

Craig Funston: I agree, but the trend toward quality is true of everything, not just marinas. If we all had to live in the small houses we had in the 1950s we wouldn’t be happy. Everything has gotten better, including marinas.

MDA: How does that present a challenge to engineers?

CF: All the easily developed sites have been taken, and we’re developing sites that are more exposed. Wave attenuator design is more critical to the success of the marina.

MDA: What are the typical misunderstandings about wave attenuators?

JC: It’s easy to overlook the complexity and believe a wave attenuator is not much different from a floating dock. They look about the same. Wave energy is almost never an orderly, singular wave with a crest parallel to the structure. It’s a complex combination of waves of different heights, directions, and periods and includes reflections and refractions from all around the harbor.

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