Slight Positive bouyancy

[onibnasir]

I intend to make my ROV slightly positive bouyant so that it would come up if connection is lost and also does not touch the ground. What are the best methods to increase the bouyancy of the ROV?

[derelicte]

two common approaches:

1. make buoyancy tank(s) bigger
2. add closed cell foam.

[onibnasir]

What is the material you use to fill in the buoyancy tank?

[Silver dollar]

The easiest way is to fill it with air.
Just make a tank out of PVC pipe and two caps and glue it together to make it water tight.

[onibnasir]

What other options are there? Just curious to know what else do people fill it with to achieve buoyancy?

[derelicte]

helium? nitrogen? hydrogen? (I wouldn't recommend that last one)

for a given volume, air will be more bouyant than closed cell foam. the advantage of the foam is is doesn't need the tanks, which reduce the effective buoyancy of the air.

the downside of cheap packing type foam is it compresses at depth and you lose buoyancy, unless you use syntatic foam like they use in commercial rovs.

[aquajack]

Helium would cost an arm and a leg, best off with air