• Early warning of coral reef degradation
  • Low-cost, local initiative design
  • Year-round water temperature and visibility
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Constructing a Rainbow Sensor Mooring.

Bill of Materials

  1. Either two or three sets of sensors. Each set has a blue, green and white sensor. These sensors need to be calibrated by the Rainbow Sensor Program.
  2. Either six or nine plastic cable ties. These are Gardner Bender Cable Ties. 8” product number 46.30BUVB. They are slightly less than 5 mm in width and fit VERY tightly into the square end of the sensor. This tight fit is critical to maintain the sensor in an upright position, perpendicular to the mooring line. A set of appropriate cable ties are supplied with the rainbow sensors from the Rainbow Sensor Program
  3. At least 25 meters of ½” poly twisted rope. 3/8” rope has been used but it is harder to pull the cable tie tight around the line to keep the sensors perpendicular to the line. Braided ½ line could work but is more difficult to force the cable tie through a portion of the line, thus preventing the sensors to slip on the line
  4. Floats. Any suitable float may be used. Polystyrene floats and empty 2 liter coke bottles have been used. Depending on the depth of the floats, ( 3 meters or 10 meters)  an appropriate number of floats should be used that connecting a 5 KG scientific instrument midway between the sensors at 12 meters and 20 meters does not cause the depth of the sensors to drop. (In the future more expensive scientific instruments may be used to relate the rainbow sensor’s OI to other instrument findings)
  5. Mooring. Any suitable mooring may be used. Existing concrete mooring blocks have been used as has metal trash that has previously been dumped on the reef. Alternatively, an eyebolt has been installed in the reef using a traditional air-powered drill that uses the compressed air in a scuba tank. (Obviously the drill must be disassembled and cleaned immediately after use to prevent corrosion.)

Construction of the Bonaire style mooring

  1. On Bonaire, moorings are constructed on land. To install a diver takes the mooring end of the line down to the mooring, threads the line through the mooring eyebolt then pulls the mooring downward until the desired depth is obtained. The diver, or divers need only pull the floats down from the surface to 3 meters.
  2. The TOP of the float is ultimately at 3 meters depth. From the top of the float measure down 5 meters. The three sensor arrays are installed in a three-point star pattern (see Figure 1.) The cable tie is FORCED into the eye of the sensor, then through all but one strand of the twisted line (see Figure 2), then tightened to the maximum using pliers to pull the cable while forcing the female end against the line until no play remains. A properly tied sensor should remain horizontal (or nearly so) when the line is in a vertical position in air. (Sensors are very slightly negatively buoyant). The sensor should be installed with the filter up. The UP side has a small flashing light to show that the sensor is launched. The DOWN side has the battery. Sensors should be installed in the order White (top), Blue (middle), Green (bottom) reasonably close together.
  3. The middle sensor array is installed at 12 meters of depth, 9 meters from the top of the float and 7 meters from the top sensor array. To the extent practical each sensor pair (white, blue, green) should be exactly 7 meters apart.
  4. The lower sensor array is installed at 20 meters of depth, 8 meters from the middle array and 17 meters from the top of the float. To the extent practical each sensor pair should be exactly 8 meters apart.
  5. What is critical for OI (Organic Index) measurement is the distance between the 12 meter and 20 meter sensor pairs. Obviously tidal action makes the actual depth of the pairs variable. Each location should set the depth to the best approximation of mean depth for their area.

Construction of a Wakatobi Style mooring

  1. The first Wakatobi style array will not be installed until about July, 2009. It is unclear at this time if Wakatobi will construct the mooring on land or underwater. When a sensor fails it must be removed from the mooring by cutting the cable tie and replaced with a new sensor underwater using a new cable tie. The sensor CAN be properly installed underwater using pliers to pull the cable tie snug. It is, however, harder.
  2. The Wakatobi style mooring has floats at 10 meters and arrays as 12 and 20 meters. Measuring and attaching rainbow sensor arrays are otherwise identical.


How The Rainbow Sensor Works
Benefits for dive guests
How To fund a Rainbow Sensor
Rainbow Sensor Poster
Rainbow Sensor Blog
Rainbow Sensor Assembly
Constructing a rainbow Sensor Mooring
Rainbow Sensor Array Configurations
Site startup Instructions
Correlation Experiment