NATCHEZ ON THE WATERFRONT17


the ‘T’ heads. However, in this case, a perimeter floating attenuator might provide a meaningful result, especially if it can also be used to accommodate larger boats, but this can also be challenging due to various regulatory conditions limiting the outboard perimeter of the facility. On many occasions, this situation occurs in facilities that have expanded over the years, but without any real master plan in mind and usually prior to recent changes in the leisure boating market. Therefore, it may be worth taking a hard look at the overall marina facility and what is really working, as well as where there are weak areas. Some years ago, the sweet spot for many marinas was with boats in the 7.5- 10.5 metre (25-35 ft) range. Today, boats have become longer and wider.


The market is changing as are the expectations of the boat-owners. A redesign to provide better wave protection can often be used to change the berthing configuration to better accommodate market requirements and while such a redesign can potentially end up with fewer total berths, it can translate to larger ones that can generate a higher income stream.


Robust approach For larger waves, a more robust approach is normally needed. Where conditions are not too severe, facilities have at times turned to the use of wave screens made of vertical or horizontal sheeting, continuous rows of piles or a combination of the two. Despite the seeming simplicity, this is not necessarily an inexpensive approach and they are not always


as effective as you might think they should be. For example, when a single row of sheets is used, the impact of the waves on the sheets can generate a new wave being formed on the marina side, perhaps not as big as the original wave, but bigger than you might have thought possible. Similarly, there are numerous


cases where gaps were left between sheets or where the sheets did not all extend deep enough, usually due to concerns either related to basin flushing or the movement of fish and other marine life. The result was significant transmission of wave energy into the marina basin. That’s not to say that at times one may have to make these types of concessions, but it is critical to understand just how much they will compromise the calmness of


A wave attenuator has been combined with a rubble mound breakwater for protection.


the marina. Single rows of vertical sheets in and of themselves are also somewhat more difficult to adopt as a multi-purpose approach for income generation, other than where the waves are small enough to have the screen attached to the side of a fixed pier – or suspended from the bottom of a floating dock/ wave attenuator, allowing boats to be berthed on the leeward side. Effectiveness at wave reduction, as well as potential for multi-purpose use can be increased with a double or triple row of sheets such as on both sides of a pier. In other cases, the sheets can be attached to a walkway, which can be used for access to boats, for fishing and/or a


MARINA INDUSTRY • FEBRUARY 2020


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