In order to keep the ROV stable in the water, you need a design that is weighted on the bottom and has floats on the top.
The first ROV was built by Steve of Homebuilt ROVs
. His website has numerous ROV designs as well as links to other ROV websites. He also incorporates several How To instructions in his site. I found this site to be invaluable in building my ROV, and would recommend it to anyone interested in building their own
The second ROV was built be Jason Rollette at Rollette.com
His design is a little different but still very effective.
For my ROV I decided on a large center tube with two smaller tube located on either side, slightly underneath the center tube.