16 NATCHEZ ON THE WATERFRONT
Wave protection – thinking outside the box
By Dan Natchez* W
hile waves are great to surf, boogie board and otherwise enjoy at the beach, they
are not desirable for the safe berthing of motor cruisers or sailing yachts. Just like boats, waves come
in all sorts of shapes and sizes. Among the most common are the relatively simple, local, every-day wind-generated waves, minor boat wakes, high energy marine ship traffic wakes and, of course, storm waves. Less commonly thought of are tsunamis, which, granted, there may not be much defence against, and the more benign, but far more common long period ocean swells. Unless one is located in a very well-protected harbour with a very slow speed limit, most wakes can be a concern for berthing boats and mitigating all but the smallest wave conditions is typically not an inexpensive task. The trick is to find the most
appropriate and cost-effective wave protection for your marina and, with some thinking outside the box, maybe even making it work for you in ways beyond its basic wave protection function. Each facility is site-specific and
one really needs to understand its challenges and advantages and how to meaningfully consider implementing wave protection. Such things as water depth, shoreline configuration, exposure to waves, current, wind and orientation of the marina to such elements are all considerations that need to be evaluated. The main weapons in the wave
protection toolbox fall into two categories – fixed or floating structures. As a general rule, what is more true than not is that floating wave attenuation is only meaningful with waves heights of up to approximately 1 metre (3 ft), but if that is all you need to handle, it can be very effective
Unless one is located in a very well-protected
harbour with a very slow speed limit, most wakes can be a concern for berthing boats and mitigating all but the smallest wave conditions is typically not an inexpensive task.
and attenuators can come in many forms. Take for example a small marina with one main pontoon that is perpendicular to the channel in a well-protected harbour where
A 6 metre (20 ft) all-concrete floating wave attenuator from SF Marina System of Sweden calms the environment at this American marina.
MARINA INDUSTRY • FEBRUARY 2020
small boat wakes are the only wave exposure, but they were rocking the boats berthed at the marina enough to be an annoyance. In this case, a simple solution was to take the ‘T’ float at the end of the pontoon and make it slightly wider, longer and heavier/deeper in draft, so that it can act as a floating wave attenuator. The result flattens the boat wakes, providing a quieter boat-berthing climate and allows the ‘T’ to become a revenue source by providing additional moorings. More challenging would be a marina with multiple main pontoons that is somewhat open to the elements. In such a case, simply widening the ‘T’s at the outboard ends of the mains is not likely to be as effective, given the exposure and the amount of open water between
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