NexSens Technology CB-40 User manual

CB-40 Data Buoy
User Guide
Last Revision: 2 February 2023
Date Generated: 3 April 2023
Copyright © 2023 NexSens Technology, Inc.

Table of Contents
1. General
CB-40 Data Buoy Overview
Key Components and Definitions
Key Specifications
CB-Series Data Buoy Planning & Precautions
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. Deployment
CB-Series Data Buoy Ballast Weight & Stability
Top-Side Weight
Ballast Weight
Mooring Data Buoys
Buoy Ballast
Mooring Eye Lifting
Data Buoy Mooring Types
CB-Series Data Buoy Deployment Tips
NexSens CB-Series Data Buoys
Connecting Mooring Hardware
Buoy Deployments
Single-Point Mooring Buoy Deployments
Two-Point and Three-Point Mooring Buoy Deployments
Planning a Medium-Deep Water Mooring for Small Data Buoys
Medium-Deep Water Deployment Considerations
Mooring Hardware Materials
Deployment
4. Warranty
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5. Service Request
Service Request
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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.
Key Components and Definitions
Buoy Hull – Constructed of cross-linked polyethylene foam with a durable polymer outer
layer and rugged stainless steel frame providing a net buoyancy of 40 lb (18 kg).
Deployment Pipe – A single 4” diameter stainless steel pass-through pipe secures water
quality sondes and other instruments with integrated power and logging and provides a
connection point for a single-point mooring system.
Key Specifications
The key specifications of the CB-40 data buoy are given below:
Hull Outer Diameter: 14.0” (35.6cm)
Hull Height: 20.0” (50.8cm)
Instrument Pipe Inner Diameter: 3.9” (9.83cm)
Instrument Pipe Height: 48.0″ (121.9cm)
Weight: 38 lb (17kg)
Net Buoyancy: 40 lb (18kg)
Hull Material: Cross-linked polyethylene foam with polyurea coating & stainless steel
deck
Hardware Material: 304 stainless steel
Mooring Attachments: 3x 5/8” eye nuts
Figure 1: CB-40 data
buoy overview.
Figure 2: Pass-through
sensor deployment.
Figure 3: Deployment
pipe & mooring eye.
Figure 4: Optional
solar marine light.
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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. When planning a buoy deployment, be sure
to give careful consideration to the following aspects:
Buoy sizing and power budget
Buoys come in various physical sizes with differing battery and solar charge capacities. A
buoy must be adequately sized to tolerate the site environmental conditions while
providing sufficient power for continuous system operation. A power budget should be
analyzed to ensure the system can meet the demand for sensor measurements and data
transmission.
Buoy ballast
Proper ballast of a buoy is critical to buoy stability when it is deployed in the water. Be sure
to review the ballast weight and stability guide when designing a buoy system. Some
experimentation may be required before final deployment.
Buoy mooring
Mooring systems come in many forms depending on the location, water depth, and
environmental conditions to which a buoy will be exposed. As a starting point, the mooring
data buoys guide provides an overview of common mooring strategies. However, NexSens
does not endorse any particular mooring strategy, and systems should be designed and
executed based on careful consideration and local knowledge of the deployment site.
Electrical connections
Many NexSens buoy systems utilize UW connectors for connection of power and sensor
cables. Data loggers such as the X2-CB have UW receptacle ports to receive sensor cables
fitted with UW plug connectors. UW connectors provide a double O-ring seal, with one O-
ring inside the receptacle and one around the plug. In order to ensure waterproof
connection, check the following each time a UW connection is made:
1. The O-ring inside the receptacle is present (has not fallen out)
2. The receptacle and plug are clean, dry and free of debris
3. The O-ring on the plug is lightly greased
4. Connection is tight, secure and fully seated
5. Unused receptacle ports are fitted with UW port plugs
Connections may be periodically inspected and maintained with O-ring grease, at a
minimum before each buoy deployment.
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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.
Safe deployment
Above all else, safety is the most critical consideration to take during the planning and
precautions of a buoy deployment. Any time a buoy system is deployed, there are
countless hazards, including, but not limited to, working on/near water and lifting of heavy
equipment. Important factors to consider for personnel safety are:
Use of safety equipment (i.e., life jackets, gloves, steel toed boots, etc.,)
Proper lifting and mooring techniques
Awareness of on-site and surrounding weather conditions and advisories
Despite careful planning and precautions, unforeseen situations are always still a
possibility. Buoy deployments are an at-risk operation, and the user assumes liability for
any injury or damages that may occur.
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2. Buoy Assembly
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. Confirm that the batteries will provide adequate power for the
duration of the deployment. Ensure that all external sensor ports and battery
compartments have a watertight seal.
1. Using a 3/16” allen wrench, remove the four bolts from the white top plate.
2. Insert the sensor into the stainless steel buoy well.
a. Ensure to remove any calibration cups and install any probe guard accessories.
3. Re-install the top plate.
a. Place a zip tie through the bolt hole of the bottom bow shackle to ensure the bolt
does not loosen during deployment.
Remove the top white plate.
Insert the sensor with the probes
facing towards the bottom of the
instrument pipe.
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M550 Beacon for CB-Series Data Buoys
The 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).
Installation
While it typically comes pre-installed, the M550 can easily be removed and/or installed by
the user. Reference the M550 Installation Instructions for guidance with the standard flange
mount version. The pole mount option can be similarly fixed to the buoy top plate using the
provided hardware and one of the pre-drilled holes on the top plate.
Figure 1: M550 Solar Marine
Light.
Figure 2: M550 pole mount
option.
Figure 3: Mounted
to top plate.
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Operation
The M550 is controlled using an IR programmer that is normally provided with the beacon.
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
Figure 4: IR
programming
remote.
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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.
NexSens Sacrificial Anodes
Anodes sourced from NexSens are sized specifically for installation onto buoy frames and
instrument cages using a pair of screws provided with the anode. They will typically need to
be replaced approximately every 6 months, though this may vary depending on factors
such as the temperature and salinity of the saltwater environment. Buoys should be
regularly inspected and anodes replaced any time it appears they will be consumed before
the next scheduled maintenance. It is often a good idea to have two anodes installed onto a
buoy – one on the frame and one on the cage – and replace them intermittently to ensure
that there is always sufficient protection for the stainless steel. Anode replacement will
require a 4-mm Allen wrench to remove the pair of screws connecting the two anode
halves.
Zinc as Anode Material
Zinc is chosen for the anode material because it is a readily-available metal with a lower
reduction potential (-0.76V) than the steel of the buoy frame. This offers the steel what is
known as cathodic protection, where oxidation reactions are transferred away from the
steel to the zinc when placed in highly ionic environments such as saltwater in the case of a
buoy. The zinc is slowly consumed by the process, hence the term sacrificial anode.
In theory, other materials besides zinc can be used as the anode as long as they rank lower
on the reduction potential scale than the stainless steel. Generally speaking, the larger the
difference between the metals on the scale, the faster the rate of the oxidation-reduction
reaction. Materials with lower reduction potential than zinc may therefore be consumed
more rapidly and require more frequent changes. Regardless of anode material chosen,
Figure 1: Sacrificial zinc
anodes.
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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.
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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.). Before
deploying a buoy system, some experimentation may be required to balance the system
properly.
Figure 1: NexSens CB-450 buoyancy diagram.
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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). In that instance, the sensor mount will cause more buoy
instability than mounted 24″ above the surface (Figure 3). As a result, the buoy would
require more subsurface ballast weight to counterbalance.
Figure 2: Top-side weight mounted higher
causes greater buoy instability.
Figure 3: Top-side weight mounted closer to the
water surface provides more stability.
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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). An instrument cage mounted to the buoy
frame helps stabilize the buoy and provides a deeper location for mounting additional
weight. For single-point mooring configurations, mooring chains and lines connected to the
bottom of the cage may provide adequate ballast. For multi-point configurations, the
mooring hardware does not contribute to the ballast weight. If needed, add ½ inch
galvanized chain (~2.3lb/ft) to the bottom of the cage, or utilize NexSens ballast weights
that can be added to the cage in specific applications.
NexSens CB-series buoy data wells are not rated for submersion, so proper ballast weight is
critical to ensure that the buoy does not overturn, including when subjected to additional
loading (e.g., high wind/waves, periodic snow/ice loads, etc.).
For information on NexSens CB-Series buoy ballast weight recommendations, follow the link
below.
NexSens CB-Series Buoy Ballast Weights
Figure 4: Ballast weight mounted deeper below
the surface provides greater buoy stability.
Figure 5: Ballast weight mounted closer to the
surface causes greater buoy instability.
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Mooring Data Buoys
This article contains only general information on the available mooring options for NexSens
data buoys. Developing an effective mooring strategy requires reviewing various
application-specific criteria (water level fluctuations, currents and wave action, debris
loads, etc.) before deployment. This document is intended to provide a starting place for
mooring design and is by no means comprehensive. Good mooring design is often
developed through years of experience with various deployment scenarios. For first-time
mooring designers, it is best to include an experienced marine engineer.
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.
Buoy Ballast
Buoy ballast is best handled by adding weight to the bottom of the buoy and not relying on
the mooring weight to act as ballast. 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.
CB-Series Data Buoy Ballast Weight & Stability
Mooring Eye Lifting
All NexSens CB-Series buoy models have three topside mooring eyes located around the
solar tower. These are sufficiently strong that a buoy can be lifted from a single top-facing
eye nut via crane or winch for removal or deployment when required. Care should always
be taken to avoid damaging any solar panels, topside sensor mounts and sensors
connected to the instrument cage when lifting and moving a buoy.
Data Buoy Mooring Types
There are three commonly used mooring types for data buoy applications:
1. Catenary moorings
2. Semi-taut two point moorings
3. Inverse-catenary (S-shape) moorings
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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.
Figure 1: Example catenary mooring
deployment with single chain for shallow
waters.
Figure 2: Example catenary mooring with
combination of rope and chain for deeper
waters.
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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.
Figure 3: Example small-buoy catenary mooring
with subsurface flotation.
Figure 4: Example small-buoy catenary mooring
with surface flotation.
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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.
Figure 5: Depiction of horizontal loading
resulting in buoy listing to one side.
Figure 6: Force diagram representing external
forces acting on buoys in natural environments.
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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. Use this mooring type only in controlled and
calm applications.
Figure 7: CB-450 data buoy with semi-taut two-point mooring setup.
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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.
Figure 8: Inverse catenary (S-shaped) mooring diagram.
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