Water pump buoyancy

[Atle.norway]

I have an idea.
I want to use an ten litre colapsable watertank connectet to a bilgepump.the idea is to use an reversible polarity switch to make the pump suck water in and out of this watertank.
With the rov having positiv bouyancy it should sit in the surface when totally empty and sink if filled up
My question is will this work.could it be that easy?
I have been tearing boldspots on my head trying to figure out how to do this with air bags and an airtank pushing water out of a watertank.and also letting water into the tank again.its just to complex for me to do with air.any advise would be helpfull,im still pulling hair waiting for an anwser.in advance thanks

[scubersteve]

How about something like this instead...
http://www.youtube.com/watch?v=nPV_ZUiJNQI

[rossrov]

Hi Atle. Consider a football bladder (or similar), sealed at slightly above atmospheric surface pressure. Put this inside the ballast tank. Use a medium pressure pump (NOT a bilge pump) to pump water into the tank. Use a high-pressure pump to pump the water out when at depth. Have blow-off valve so tank will not be pressurised (safety) if you have to drag to surface with the tether.

Ross

[Atle.norway]

Thanks will try that.anyway are you thinking of a football pump to use for waterpumping?

[rossrov]

rov ballast tank.jpg (151.84 KiB) Viewed 5280 times

Probably easier to use just one pump. Here's a drawing of the concept.
The pump idea in the video Steve posted would be simpler I think for small volumes of water. How much volume do you really need to move?

[dna1990]

How deep you going?

If not terribly far, how about running an airline to the surface? MATE teams do this for both dynamic buoyancy and activating pneumatic devices. Simple hand pumps to full compressors with check valves, etc. ~1/4" tubing generally used.

[Atle.norway]

Aprox 10 kg weight and not deeper than 8 meters