I performed an inspection of a 2,400ft long, 24" diameter treated sewer outfall with a modified BR2. I used two 50cm 3" cast acrylic tubes as the chassis to mount the electronics enclosure and thrusters. The two tubes were secured together by attaching the enclosure clamps to each other. I also mounted the thrusters,lights, electronics enclosure and buoyancy to the enclosure clamps.
I wanted to have plenty of battery capacity to haul the fiber optic tether, and to have plenty of time to perform the inspection without ‘range anxiety’ compromising the time spent looking at features so I connected the 6 batteries with an array of 7 of our battery managers…. I removed the outer cover from the Li-ion batteries and removed one of the 3 foam inserts that run the length of the battery to make room for the power cables.
The inspection took 5.5 hours and I used 44Ah out of the 108Ah capacity.
Some of the diffusers had broken, filling the invert of the pipe with sand and rocks so I couldn’t inspect the full 3,000ft of pipe. A rock with seaweed attached got stuck on the starboard side thrusters which made it difficult to maneuver the vehicle but fortunately that occurred towards the end of the inspection.
It was blowing a gale of freezing rain during the inspection which was pretty miserable for the two guys that were tending the tether. I worked out of our control trailer.
To record the penetration distance, I run the tether through a line counter quadrature encoder that connects to an Arduino based circuit board which outputs a comma separated data string of counts, meters, feet and station via rs485. The RS485 connects to a Proteus HD Overlay Device which is connected between the laptops’ HDMI output and an Atomos Shogun recorder.