Team name: The Typewriter Repairmen

Robot: A steel strap frame with heavy steel bottom rails that holds a big Lexan tube laterally at front-top for the cameras/electronics and two 100mm dia, 30cm long buoyancy tubes across the sides at top. Buoyancy adjustment is done on the surface with petcock valves.

Lexan tube: 3mm wall, 150mm dia, 250mm long. Two 12mm thick, turned aluminum end plugs with O-rings and flanges keep water out and provide mounting for electronics and heat sinking for hot things. 

Motors: Four bilge pump motors with 75mm dia. ducted props for up/down(1), forward/reverse/rotate(2) and sideways(1). Each motor has a bidirectional speed controller mounted in the tube that sucks on 48V. 

Manipulator: One motor to squeeze and release two 50mm square vertical paddles. Located about 150mm in front of robot, flush with bottom of rail surface. 

Cameras: Two Radio Shack security cameras with original lenses, mounted 100mm apart on centers for stereo vision.

Camera mounting: The cameras and lights are mounted in a sectioned boat that can tilt up/down under servo control over a 90 degree range. 

Lights: One 12V 20 watt flood for distance driving, four 3W LEDs for close work, maybe one 50W wide for search, floating on the surface. 

Motor controllers: Each motor controller has a PWM input that commands speed and direction in a linear way.

Batteries: On the surface, four 12V 12AH AGM sealed lead-acid wired in series to make 48V. A 15 amp fuse protects the batteries from the robot. 

Solar charger: David has a 75W solar panel that will be used to charge the four batteries in parallel during the daytime event. This requires some clarification of the rules, as they state that the batteries must be discharged to 20% below their nominal voltage, which is forbidden by the battery data sheets.  

Tether: Two Ethernet cables and one zip cord braided together with a 19mm foam flotation strip and no wire ties to snag.  Total length 22m, floating length 18m.

Motor control box: A Vex transmitter. One joystick for forward/reverse/rotate and the other for up/down and sideways. Buttons currently unallocated. 

Camera/manipulator box: Another Vex transmitter. One joystick for camera tilt up/down, the other for manipulator squeeze/release, buttons for floodlight on/off. Ability to add up to 3 extra control functions as needed. 

Telemetry: Pressure gage with 3 digit DVM readout, audio recorder and output signal, two NTSC video outputs, temperature probe (thermistor?) with 3 digit DVM readout.

LED power:

The LEDs will run from two series strings of 2 or 3 LEDs each. A dropping resistor matches them to 12V. This resistor will get hot, so it's mounted to a metal plate. We need 6.8 ohm at 10 watts for two LEDs or 2.2 ohms at 2 watts for 3 LEDs. 

P2.2W-2BK-ND	Panasonic 2.2 ohm 2W metal film axial
6.8W-10-ND	Yageo 6.8 ohm 10W WW axial square

Motors: 

Johnson Motors makes the motor in the Rule pump. The 360GPM uses a 12V 35x50mm motor rated at 2A. I took it apart to see what makes it tick.

The shaft seal is a rubber disc that rubs against the motor housing. Large surface area, low force. The motor wires are molded into a rubber boot that fits in an oblong hole in the housing. The housing pieces are welded together somehow. The motor itself is a standard brushed type with some noise suppressor on the commutator - it's a ceramic ring with five copper solder pads.