Bouyancy Problems

[rovdude]

Ok.... so. When I originally started my own custom ROV, I took note of some issues a SEAPERCH kit had. At a certain depth, the ROV would sink and the motors were not powerful enough to bring the ROV back to the surface. It used simple foam tubes for buoyancy. I judged that under pressure the motors could not bring the ROV up. While this is true, it is because the pressure was squeezing air out of the foam - which I just realized. On my new ROV I plan to use some PVC pipe sealed with air. When I originally tested my ROV, without the air for buoyancy, my vertical motors could not bring the ROV to the surface at 5 feet down. When I put the sealed pipe with air in it on, will my motors be able to better maneuver my ROV vertically? Even at a depth of 100 feet? I know it will change where the ROV is buoyant at, but will it help my motors get my ROV all the way to the surface?

[orangeltr456]

I Competed in the Maryland sea-perch competition the last 2 years. The foam noodles used are obsolete for the reasons you mentioned. The foam dose not resist the pressure very well and the tiny air bubbles collapse.

Our solution for this problem ( to dive 16ft down for the competition) we used 1 1/2 inch pvc with end caps on them. about 2 feet total . It worked well and made it easy to adjust center of buoyancy. I do not think the motors will withstand 100ft. Mine failed at about 30ft the photo containers are very weak and the water can push its way around the wax and onto the motors.

I changed the film canisters to pill bottles because they are stronger and make a better seal . I doubt they would be able to withstand 100ft though