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Water Leak Testing

    The team conducted tests on several components of the submersible robot to minimize any problems during assembly and the final testing phase.  One of these components was the PVC housing.  The test plan required the submersible robot to be placed in the water so that two objectives could be reached.  The first objective was to inspect the housing for any possible leaks while it was submerged.  This was done by sinking the housing in a pool at several depths by attaching weights to the housing, to see if added pressure caused any signs of leaking.  This test was conducted at depths from zero to ten feet.  While the robot is being designed to operate at depths of three hundred feet the team cannot realistically test at this depth so the team conducted the test in a pool where the team could monitor the housing for leakage.  The tests concluded that there were no leaks coming from the housing so the team considered this to be a success.  In conducting this test the team was particularly concerned about leaks at the threaded end caps, since threading the end caps was a requirement for the robot to be accessible for repairs and for the retrieval of the sensors. 

            The second objective was to verify the buoyancy calculations for the housing.  This was done by tying rope around the outside of the housing and attaching increasing increments of weight until the housing was no longer neutrally buoyant.  The team found that the housing was no longer buoyant between 5lbs and 7.5lbs.  In comparing this to the values the team found using buoyancy calculations in which the team considered the volume of the water displaced times the density of water the team was able to come up with a mass that would make the robot neutrally buoyant.  The team found this value to be at 5.745 lbs which is in between the values the team found during testing.  The team would have liked to have been able to get greater accuracy during the testing but weight increments were available in 2.5 lbs increments only, so the team was satisfied after verifying the range around the actual value.  This test was conducted only for the 10in housing which is the dry section of the wet/dry chamber of the submersible robot.  While further tests could have been completed the team decided there was no critical information that could have been attained if the rest of the housing was tested since the actual test supported the calculated value.  This being the case the buoyancy of the submersible robot is 18.9 lbs with two housings and is 27.5lbs with the third housing which contains the electrical components.  The total mass of components at this point is 22.0lbs which gives the team 5.5lbs of mass for the sensor package which may be installed at a future date.