Install Instrument Cage

CB-series data buoys allow for an instrument cage to be installed on the bottom for stability and/or mounting of sensors.

instrument cage

Figure 1: Instrument Cage


1. To install the cage, first remove the 3/4”-10 x 4” bolt, 3/4” lock washer and 3/4”-10 castle nut from the cage or buoy frame.

2. Run the bolt downward through the buoy frame and top of the cage. Place the lock washer and nut onto the bolt.

3. Tighten very firmly with a pair of 1-1/8” or adjustable crescent wrenches.


Figure 2: Instrument Cage Connection


4. Ensure that the lock washer is flattened and the hole in the bolt lines up with the notches in the castle nut. A large amount of force may be necessary to properly align the nut.


Figure 3: Castle Nut Alignment


5. Place the cotter pin through the hole in the bolt, and bend the long leg of the pin to prevent the cage from loosening.


Figure 4: Castle Nut Installation


6. Welding the cage and/or installing additional security straps is also recommended for use in rough water. If using a CB-CCA cage clamp accessory to prevent rotation and loosening, follow the instructions provided with the clamp for installation.


Figure 5: Cage with CB-CCA Clamp


Ballast Weight

Proper ballast weight is essential to prevent buoy overturning. Carefully consider the site-specific ballast requirements prior to deployment. See the following link for additional information:

For some applications where additional ballast is required, a 25 lb weight is available for installation to the bottom of the instrument cage. Begin installation by inserting the 9-3/4” threaded rod section through the ballast weight and bottom of the buoy frame or instrument cage assembly.

Inserting the Threaded Rod

Figure 6: Inserting Threaded Rod


On the bottom end of the rod, tighten a 3/4” eye nut with a 3/4” lock washer. Tighten the top end of the rod securely to the buoy frame or instrument cage with a 3/4”-10 nut and 3/4” lock washer. Weld the connections to prevent loosening in rough water.

Securing the Ballast Weight

Figure 7: Securing the Ballast Weight


Securing the Ballast Weight

Figure 8: Securing the Ballast Weight



REV: 15B17

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