BOUYANCY AND OTHER IDEAS

[BOBSCNC]

I was working on an rov about 25 to 30 years ago. now things are very different. One of my ideas for building a housing was to pressurise it. I repaired SCUBA and other types of regulators so I was very familiar with the principles of operation. BY modifying a regulator it could be mounted on a ROV hull. Wjat it would basically do when set up properly is put the air pressure inside the hull at a pre set pressure, say 3 PSI, greater then the water pressure. You would have a pressure relief valve set for 5 PSI on the hull. This would release pressure as the ROV ascended.


The advantages are:
you can build a lightweight housing.
use a better camera that is not water proof.
any leaks in the hull would let air out not water in.
The video port could be made of a lower cost material.

Disadvantages are
The need to have an air tank in the ROV or in the tether line.

There would be a fail safe that in the event of problems an airbag would deploy to return the ROV to the surface.

20 years ago we had built one that used 1/8 " plexiglass and put it down to 200 ft of water with a still camera in it. We used standard car headlights for a light source.


I have a 22ft pontoon boat that when I am not fish can be used to support the project. If I sell some items I have for sale I may even have a 28 ft boat on Lake Michigan. I has beatiful clear water with depths to 800 ft plus for testing.

I would love to hear from any one in the wisconsin area.

I would love to have comments and input on this ideas


Bob N.

[tazdevl77]

Bob, very interested in this concept since it's in line with an idea I had for using pressurized oil. But I feel your idea of using pressurized air is better. Another advantage of it is you can pipe pressurized lines to the thrusters to greatly increase the depth of modified bilge pump thrusters. Keep us updated on what type of system you come up with. An option other than using a full blown scuba tank for the compressed air is to use one or more of those 20 ounce CO2 tanks commonly used in paint ball. The tanks are small, made of aluminum, have a 3000 PSI rupture rating, and have a service rating of 1800 PSI. So you can comfortably put 1000 PSI of pressure in just one, which should more than handle the pressure needs of any amateur ROV (I believe 1800 PSI = 4040 feet depth of water). I've found them online relatively cheap from $12-$25 each. The only questions are: Can SCUBA regulators, etc run off CO2?, and if not, can these tanks be filled with SCUBA type air instead of CO2? Another more expensive and heavier option is to use the smaller SCUBA tanks. Here are the spec on the tank I'm talking about: Service Pressure of 1800PSI/ 123 BAR, 3.2" diameter x 9.38" length, 1.5 lbs weight, CO2 Capacity of 1.25lbs, air capacity of 3.7 cu feet, H2O Capacity of 51 cu inches, O-Ring Seat Diameter of .750", and 5/8-18UNF-2B threads. Keep us posted on your design! Tim

[amsjohn]

Bob,

You need to think about it a little a SCUBA tank weights about 35lbs at the surface and as you go deeper the air compresses and it get about 3lbs heaver to stop a few leaks you build the rov to hold this weight you might want to build it as a 1 amp sub with no leaks it will be chepper in the long run. The idea with oil is good, fluids don't compress. So you can still build it cheeper. John :ugeek:

[bluewavecaptain]

I was working on an rov about 25 to 30 years ago. now things are very different. One of my ideas for building a housing was to pressurise it. I repaired SCUBA and other types of regulators so I was very familiar with the principles of operation. BY modifying a regulator it could be mounted on a ROV hull. Wjat it would basically do when set up properly is put the air pressure inside the hull at a pre set pressure, say 3 PSI, greater then the water pressure. You would have a pressure relief valve set for 5 PSI on the hull. This would release pressure as the ROV ascended.


The advantages are:
you can build a lightweight housing.
use a better camera that is not water proof.
any leaks in the hull would let air out not water in.
The video port could be made of a lower cost material.

Disadvantages are
The need to have an air tank in the ROV or in the tether line.

There would be a fail safe that in the event of problems an airbag would deploy to return the ROV to the surface.

20 years ago we had built one that used 1/8 " plexiglass and put it down to 200 ft of water with a still camera in it. We used standard car headlights for a light source.


I have a 22ft pontoon boat that when I am not fish can be used to support the project. If I sell some items I have for sale I may even have a 28 ft boat on Lake Michigan. I has beatiful clear water with depths to 800 ft plus for testing.

I would love to hear from any one in the wisconsin area.

I would love to have comments and input on this ideas


Bob N.

I live in Green Bay, Wisconsin. I'm trying to work on building a ROV for exploring Lake Michigan shipwrecks. I'm struggling with the tether and keeping the sub dry. What about having a resevoir for a type of liquid gas inside the sub? Such as liquid oxygen or helium. If the sub would develop a leak, the liquid would slowly vaporize keeping pressure inside the sub. The only obstacle would be how to set it up inside without damaging the electronics. I'm toying with the idea of electro-magentic drives. Something like tabletop water fountains and fish tank filters have.