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Harbor and Marina Services

What's Down There?

The truth is that until and unless you perform a thorough inspection to find out, you simply have no idea what's going on under the water in your harbor or marina. Erosion and corrosion could be bringing some portion of your facility to the brink of collapse. If you don't have a proactive inspection program in your facility, then the only way you'll find out is when that collapse happens. If even a single injury or property loss incident result, then the costs your facility will be facing will be orders of magnitude beyond what a proactive inspection would have cost. Wouldn't you rather know and be able to react before disaster strikes?

How We Can Help

We recommend a proactive maintenance inspection be done in two stages:

  • A wide-area sonar survey of the bottom of the more open areas of your facility to look for any unknown hazards and/or problematic sediment movement. Any large, relatively unobstructed vertical surfaces like sewalls or breakwaters may also be examined in this way. This type of survey is usually done with an imaging sonar unit deployed close to the bottom from shore or a small boat.

  • Closeup, detailed video and sonar inspections of critical infrastructure and detail-rich environments where wide-area techniques can't capture enough detail. Our compact, easily deployed ROV is ideal for this kind of work. Equipped with multiple cameras and scanning and multibeam imaging sonars as needed, our vehicle can pore over every detail of your facility to ensure that no problem is overlooked.

Below you'll find some examples of the kind of data our inspections can produce. This first image is a mosaic of several sonar scans combined with Google Earth imagery creating a seamless above-and-below the water view of a small marina.

The next images illustrates the general method of operation and level of detail available with typical imaging sonar equipment. In it we see the bottom and a portion of the side wall of a drydock as if viewed from above. The sonar is positioned at the center of the image. In reality, it is hanging from a tripod a couple of feet off the bottom of the drydock. It works somewhat like a lantern, shining its light in a narrow beam all around itself horizontally. It lights up objects sitting on the bottom, which then cast shadows behind them. The low angle of incidence of the lantern's light helps to show the texture of the bottom, while vertical surfaces like the drydock wall show up as especially bright. Of course, the sonar is using sound to do all this, not light, but the end result is much the same for our purposes.

The next images illustrate how imaging sonar can be used to inspect vertical surfaces such as seawalls and bridge abutments. The first image is a mosaic combining a single sonar scan with a single photograph. In this case, our "lantern" is shining narrow, vertical beams out to either side, aligned with the face of the seawall that is of interest.  It captures a good deal of detail and if any major defects were present they would be apparent. The second image is a mosaic of a single picture combined with sonar data from multiple scans to depict a large area in a seamless above-and-below the waterline view of a very complex environment.

Lastly we have some examples of the level of detail with which the latest multibeam sonars can "see" objects at close range in even zero-visibility conditions. The images shown above were generated by scanning imaging sonar units, which work much like we think of air-traffic control radars working, with a single beam that spins around, refreshing its image of its surroundings as it goes. Multibeam sonars work much more like a primitive video camera, producing a "live video" kind of image. It's still a "view from above" kind of perspective, and only of a pizza-slice-like section of its surroundings with the sonar at the pointy end of the slice instead of a full 360-degree view, but the video-like speed and detail available make these sonars invaluable tools in low-visibility and close-range conditions.

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