Daily Journal

December 6, 2004: Recovering the Mooring

One of the most important activities of this cruise was the retrieval of the instruments moored during the December 2003 cruise. This mooring was placed in the San Clemente basin, near the island of San Clemente. An acoustic signal was sent to release the mooring from the ocean floor where it was anchored to 3 railroad wheels. These wheels remained on the ocean floor. Although we had a radio beacon to assist in locating the mooring, the glass float spar buoy was sighted from the bridge. The recovery of the mooring was a process that lasted most of the day and involved the entire crew.

Question 1: On a map (preferably from an atlas that shows the coastline from San Diego south to Ensenada, Mexico) see if you can locate the island of San Clemente. This island is not inhabited and is used by the U.S. military for training. Now look on a map that shows Puerto Rico. Can you find the island that the U.S. military uses for training in that area?

The mooring consisted of two sediment traps, two sets of floats, a current meter and two transmissometers (used to measure particles in the water). One sediment trap was placed at 1500m and the other at 1850m.

Question 2: If you are not familiar with the length of a 50m swimming pool, see if you can find an illustration of one on the Internet or in another resource. How many pools would you need to stack end to end to be equal to the depth of 1500m?

The purpose of the sediment traps is to collect samples to measure the distribution of barite on the ocean floor Each sediment trap was set to collect and seal 15 separate samples over the period of the year. However, due to unforeseen problems, only 5 samples were actually recovered.

Question 3: What percent of the target sample was actually collected? Write your answer as a percent, fraction, and decimal.

glass float Spar Buoy and glass floats used to locate sediment trap

Sediment trap recovery

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