Once the ROV gets a little way under the water, it's going to get dark. Obviously I'll need some sort of underwater lighting.

My first though had been to include lights inside the camera tube (in a similar way to those used in the OpenROV project). However, I think this could easily result in glare on the inside of the acrylic tube; so it would be better to mount the LEDs outside. To do this I needed some way to encapsulate them.

For simplicity, I've chosen to use lengths of LEDs lights from eBay. These cost about $0.03 per LED (super cheap!) and each LED produces 50 lumens. I mounting 2 tubes of LEDS, which each tube holding 15. This gives me a total of 1500 lumens of light.

My first attempt was to mount the LEDs in vinyl tubing, and then encapsulate them inside the tubes using epoxy.

This was a bit of a failure for a number of reasons. First, its very difficult go get these tubes to be and stay straight. Second, the LEDs come with glue to make them easy to mount - but that's not useful inside the round tube. Finally, because you have to pour the epoxy in one end of the tube, its very difficult to remove the bubbles.

My second attempt was more successful. For this I made an acrylic case using a laser cutter. This is flat, which is better for mounting and better for sticking the LEDs to. I can also fill it with QSil to waterproof the LEDs by pouring into the open contains (ie. not from the end). I can then close and seal the acrylic case - once the air has escaped the QSil - for a good, waterproof seal.

The result is 750 lumens of waterproof LEDs for less than a buck.