NexSens CB-50 User Guide

The NexSens CB-50 Data Buoy is designed to accommodate NexSens SDL submersible data loggers for quick deployment and immediate environmental monitoring. The CB-50 is constructed for deployment in  lakes, rivers, coastal waters, harbors, estuaries, and other freshwater or marine environments where environmental data collection is planned.


CB-50 Data Buoy



Instrument Cage

An instrument cage is included with the purchase of a CB-50 data buoy. The instrument cage provides ballast weight and establishes points for mooring or sensor mounting.

Instrument Cage for CB-50




Instrument Cage Assembly

  1. Attach the cage to the buoy frame using the ¾” bolt, lock washer and castle nut.
    1. Reference the CB-50 diagram below

      Cage attachment to buoy frame


      CB-50 Diagram


  2. Tighten firmly with 1-1/8” wrenches or large crescent wrenches. Be sure to flatten the lock washer and lineup the hole in the bolt with the notches in the castle nut.

    Cage to frame connection


  3. Place the cotter pin through the hole in the bolt, and bend the long leg of the pin to prevent the nut from coming loose.

    Cotter pin installation


Accessing the Data Well

A removable topside foam tower with lid protects on-board electronics, supports solar marine lights, and offers a convenient lifting point. The NexSens X2-SDL submersible data logger is designed to be installed in the center of the buoy hull.

Install an X2-SDL data logger

1. Loosen and remove the three top-facing eye nuts and threaded rod assemblies on the top of the buoy.

Loosen eye nuts and remove threaded rods.


2. Remove the white buoy lid and lift the top foam tower off of the buoy base.

Remove foam top to expose the data well.


3.  Insert the X2-SDL into the data well of the CB-50. Push down until the top exterior orange O-ring rests against the well plate.

a.  It will be necessary to remove the orange exterior O-ring at the bottom of the X2-SDL for the logger to fit.


Inserting a X2-SDL logger into a CB-50 buoy data well.




Safety First

Always follow safe marine and boating practices.


  • Heavy gear and boat clutter during deployment is unsafe. Care must be taken during deployment to maintain a clean and safe environment.
  • Use proper protective equipment (work boat, lifting rig, gloves, safety footwear, etc.) when deploying any buoy system.
  • Buoy systems are heavy, and personnel can quickly become entangled within mooring lines. Flotation gear should be worn at all times when working on or near the water.
  • Never deploy buoys in unsafe weather conditions.

Ballast Weight and Stability

To prevent overturning and ensure stability, additional ballast weight may be needed.


  • As configured at the factory, the buoy’s center of gravity is near the water surface. Any weight added above the water surface must be appropriately counterbalanced by additional ballast weight below the surface.
  • Be sure to keep topside devices lightweight and positioned as low as possible on the tower. Mount the ballast weight as low as possible on the underside of the buoy. It is preferred that the ballast weight be connected to the eye of the instrument cage.
  • It is recommended to use galvanized chain for ballast, however, the exact weight is dependent upon the conditions at the deployment location.
  • Before final deployment, some experimentation with ballast weight may be required to properly balance the buoy.



CB-50 Ballast Weight diagram


Excess ballast weight may result in the submersion of the SDL bulkhead and a subsequent decline in both remote communication performance and life of the data logger.

Reference the diagram below before deployment to ensure that the water level does not submerge the SDL entirely for an extended period of time.


CB-50 water level diagram



Mooring Options



Single-Point Mooring


  1. Attach a stainless steel mooring line to the bottom eye of the instrument cage.
    1. Ensure that the mooring line has adequate length to remain taut in the water column.
  2. Shackle a heavy chain to the bottom of the mooring line.
    1. Confirm that the chain is long enough so that the anchor cannot be lifted during high water conditions.
  3. Connect an anchor to the bottom of the chain.


Important: This section contains only general information on the available mooring options for CB-50 data buoys. To develop an effective mooring strategy, a variety of application-specific criteria (water level fluctuations, currents and wave action, debris loads, etc.) must be thoroughly reviewed prior to deployment. NexSens does not endorse any particular mooring strategy for any specific application.