Buoy sizing and power budget Buoy ballast Buoy mooring Electrical connections Safe deployment 2. Buoy Assembly Instrument Installation in CB-40 Data Buoy M550 Beacon for CB-Series Data Buoys Installation Operation Use of Sacrificial Anodes on CB-Series Data Buoys NexSens Sacrificial Anodes Zinc as Anode Material 3.
1. General CB-40 Data Buoy Overview The CB-40 data buoy is a simple, compact platform for deploying water quality sondes and other instruments that integrate power and data logging. It features an integrated 4″ diameter stainless steel slotted instrument pipe and supports mounting of an optional 1-3 nautical mile light for deployment in navigable waters.
CB-Series Data Buoy Planning & Precautions Buoy deployments are usually complex operations that involve many elements including sensors, data loggers, mounting hardware, and mooring equipment. Careful planning and precautions are essential to the success of a buoy project, not only for system operation and data collection but also to ensure the safety of project personnel and minimize the risk of damage to expensive system components.
CB-Series data buoys contain a waterproof data well constructed of stainless steel where batteries are mounted. Whenever installing or maintaining battery systems, use caution to avoid short-circuiting of battery poles to the metal walls of the data well. Gloves and tools with rubber grips are recommended, and any exposed connections should always be covered with electrical tape or other suitable coverings.
Instrument Installation in CB-40 Data Buoy A water quality sonde or other instrument can easily be installed in the 4″ deployment pipe of the CB-40 buoy by removing the top cover. IMPORTANT – BEFORE FIELD DEPLOYMENT: Completely configure and test the internal logging of the sensor.
M550 Beacon for CB-Series Data Buoys NexSens M550 Solar Marine Light is a common accessory added to NexSens CB-Series data buoys up to and including the CB-450. Depending on the configuration, it has a 1-3 nautical mile range and is normally delivered with flange mount hardware, yellow color and default 15 flash/minute pattern (Model M550-F-Y).
Operation The M550 is controlled using an IR programmer that is normally provided with the beacon. Figure 4: IR programming remote. The IR programmer can be used to perform the following functions: Turn beacon on and off Check the battery pack charge status Change the flash pattern Change the flash intensity...
Use of Sacrificial Anodes on CB-Series Data Buoys Sacrificial zinc anodes are recommended for use on CB-Series data buoys any time they will be used in saltwater environments. This helps to prevent corrosion on the stainless steel frame, as zinc is a more active metal that will be consumed while protecting the stainless steel.
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frequent inspection and replacement of anodes as needed can extend the life of a data buoy significantly in saltwater. Sacrificial anodes are normally not necessary for buoys used in freshwater except in special circumstances. It is therefore generally recommended only to order anodes with buoys intended for use in brackish or saltwater.
3. Deployment CB-Series Data Buoy Ballast Weight & Stability Ballast weight may be needed to prevent overturning a CB-series buoy system and ensure stability in the water. The center of gravity of NexSens CB-Series buoys is near the water surface without instruments connected. Therefore, any top-side weight added above the water’s surface (e.g., sensors, sensor mounts) must be appropriately counterbalanced by ballast weight below the surface (e.g., instrument cage, chain, anchors, etc.).
Top-Side Weight Top-side weight is any weight mounted on the buoy above the water surface or the buoy’s center of gravity. Weight located further from the buoy’s center of gravity will cause greater instability of the buoy. For example, suppose a weather sensor is mounted 36″ above the water surface (Figure 2).
Ballast Weight Ballast weight is any weight mounted on the buoy below the water surface or the buoy’s center of gravity. Contrary to top-side weight, a ballast weight added further below the surface (Figure 4) will provide a more significant stabilizing effect than the same size weight mounted closer to the surface (Figure 5).
Additionally, the weight associated with biofouling growth can impact the buoy buoyancy and mooring performance. Minimum recommended ballast weights for NexSens Technology data buoys can be reviewed at the link below. NexSens Technology Buoy Ballast Weights More information on buoy ballast can also be found at the link below.
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1. Catenary Moorings For shallow deployments with minimal wind, wave and current loading, most data buoys utilize catenary moorings. Shallow deployments can be designed with all chain or a combination of heavy bottom chain and light water column chain. Deeper water moorings may need to use a combination of chain and rope.
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Small-buoy catenary moorings Additional surface or subsurface floatation may be required for smaller buoyancy buoy applications where the floatation may not be adequate to support the mooring weight. Extra floatation can also free motion for wave measurement applications or offer additional resistance to horizontal loading.
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Horizontal Loading As wind, wave and current loads increase, the buoy is driven away from the anchor and mooring can be pulled taut resulting in the buoy listing to one side. Damage can result with topside equipment and solar panels becoming submerged. Additional surface or subsurface floatation may be required.
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2. Semi-taut two point moorings For calm, shallow water with limited horizontal loading, semi-taut two point moorings can be utilized. These moorings are useful for suspending sensor lines by pulling the mooring lines free and clear. Rough water, shifting bottom or horizontal loads can tangle two point moorings and lead to chafing and cable failure.
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3. Inverse-catenary (S-shape) moorings Inverse-catenary moorings are often referred to as S-shaped moorings. Floats and weights on the mooring lines create an S-shape, which provides spring action in the water column. Waves and water level changes are easily managed. This mooring type is most common on deep water deployments but has utility in shallow rough water applications.
CB-Series Data Buoy Deployment Tips NexSens Technology supplies mooring hardware to support user-designed systems but does not endorse any particular mooring strategy for any specific application and does not take responsibility for mooring performance or damage resulting from mooring failure.
Note: Shackle sizes are dependent on the thickness of the bottom chain. Shackles shown in the images below are used for 1/2″ galvanized chain, which is standard in most applications. Figure 2: Shackle connections between the Figure 3: Shackle connections between the buoy tether line and marker buoy.
equipment (e.g., workboat, lifting rig for heavier systems, gloves, safety footwear, etc.) is essential to deploy any buoy system safely. Buoy systems are heavy, and personnel can quickly become entangled with mooring lines and anchors. Safety and flotation gear should be worn at all times when working on or near the water.
Figure 7: Single-point mooring system on CB- 450 data buoy. Two-Point and Three-Point Mooring Buoy Deployments 1. Connect all mooring components inside the boat. Stage the components so that they can be lifted over the side of the boat and laid out without becoming entangled. 2.
Planning a Medium-Deep Water Mooring for Small Data Buoys Note: NexSens Technology supplies mooring hardware to support user-designed systems but does not endorse any particular mooring strategy for any specific application and does not take responsibility for mooring performance or damage resulting from mooring failure.
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Mooring Line Length and Drift Radius In order to determine the appropriate mooring line length, it is first necessary to have a fairly accurate water depth measurement at the deployment site and overview of the expected water level changes. In most applications, mooring line lengths should be ~50% greater than the median water depth to account for water level fluctuations.
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Figure 2: Depiction of horizontal loading Figure 3: Force diagram representing external resulting in buoy listing to one side. forces acting on buoys in natural environments. A general principle is that the buoy should be allowed to move somewhat freely with waves and currents rather than attempting to firmly hold it in place at an exact point.
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Figure 4: Mooring system overview with trawl float supporting bottom chain. System Maintenance A secondary consideration in calculation of mooring line length is serviceability of the instruments deployed. For practicality, it may be desirable to be able to access sensors mounted along the mooring line without having to lift the entire anchor system from its placement.
Mooring Hardware Materials Mooring Lines A wide range of hardware options are available, and these can largely be selected based on site conditions, but there are a few critical points which should be considered. Sensors suspended below the buoy frame can optionally be mounted onto NexSens-issued stainless steel mooring lines.
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Figure 5: S-shaped mooring with weight applied to avoid mooring rope coming into contact with sensors. Mooring Connections To connect mooring components together, various shackle types may be used. Here, it is important to consider the materials of construction. The internal frame of CB-Series buoys is constructed of Type 316 stainless steel.
rotate around the mooring line connection. An exception to this would be if no sensors are suspended below the depth of the buoy’s internal frame. Deployment Due to the size and total weight of medium-deep water moorings, it is strongly recommended to deploy using an appropriately-sized vessel equipped with a crane and winch for controlled lifting and release of the mooring system and buoy.
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Figure 8: Figure 7: Anchor being Anchor lowered into supported by water with off-load hook. crane. 3. After drawing the wire of the crane back to its original parked position, begin slowly paying out the mooring line using the winch. Before the anchor touches the seafloor, there is the possibility to make fine adjustments to the mooring location by carefully navigating the vessel, being sure to avoid tangling of the mooring line with the motor.
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if the vessel is equipped with one. Once deployed, observe the buoy’s movement to ensure it appears to be stable. If the buoy is equipped with a GPS device, track the coordinates for a few days to ensure it is staying within the desired drift radius, and consider configuring a geofence alarm to provide notice if the buoy moves outside the desired boundaries.
Limitation of Warranty This warranty is not applicable to any NexSens Technology, Inc. product damage or failure caused by failure to install, operate or use the product in accordance with NexSens Technology, Inc.
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5. Service Request Service Request To return equipment for evaluation and repair, request Return Authorization (RA) are the following link: NexSens Return Authorization An email authorization receipt with reference number will be sent to print and include with your shipment. Products within the warranty period will be fixed at no charge.
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