Homebuilt ROVs Forum

hey fellow rov builders!!!! jeff here from malaysia. I'm a 2nd year mechanical engineering student. tryin to build a whole new concept of ROV. durin my 1st year i was using a change in volume concept to make the ROV submerge and float. The design for such ROV is totally insane, if we change the volume of the object, the centroid of the object will change. therefore it will end up out of balance. Very unique design needs to be done . Therefore i planned to stick back to old concept. But i dun really understand about one part of the mini home ROV. As i know the industrial ROVs are using the ballast tank to make it submerge and float. I do not see any of these mini ROV with a ballast tank, but oni a thruster to have a external force to drive it down. Won't de buoyancy force drives it back up? how does it sustain at certain depth? please enlighten me, really curious here

Hello Jeff,
The micro-class ROVs are neutral buoyant meaning they sit in the water without floating or sinking so to speak.
They don't do much in the water, that single prop you see shall force it down and because it has a neutral buoyancy it shall stay down there (sometimes tiny movements are required to keep it down due to currents e.t.c.)
Because it has a neutral buoyancy the prop just needs to be reversed and it comes back up, larger ROVs use ballasts because they are work horses... they need to stay down, when they carry lots of stuff for repairs e.t.c. they can't keep on changing the buoyancy to keep it functioning.

I hope this helps!