AT CAD Team/AT underwater vehicle
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[edit] Use
The AT underwater vehicle is to be used as a movable moon pool (see previous version of the image), hereby facilitating work carried out underwater (such as coral reef rehabilitation, ...). The cabin in which the 4 divers take place immediatelly works as a buoyancy control device, hence lowering or heigtening the vessel towards the water surface. This is done as follows: upon reaching the destination, manifold hose 1 to manifold hose 4 is disconnected from the outside of the vessel letting water in; this lowers the vessel from 1m below the water surface to 5-8m below the water surface. Once the vessel is nearly full, the hatch is opened (using MPB 2, located on inside) and the divers swim out. The manifold hoses are then connected to the diving helmets of the divers. Before they connect the hoses, they make sure that the compressor is set to mode 1A, this means that the compressor runs at 1/4th of its full speed, this being enough pressure for all 4 divers at about 6m depth (= the depth at which divers do not need to decompress and can return immediatly to the surface in case of trouble).
The compressor has 3 modes:
- mode 1A: 1/4 of full compressor power; allows air to be compressed enough to allow 4 divers to breathe underwater trough their surface supplied diving lines (= manifold hose 1 to manifold hose 4).
- mode 1B: 1/2 of full compressor power; allows air to be compressed enough to allow filling the vessel with air
- mode 2: full compressor power; allows air to be compressed enough to allow boating the vessel with supercavitation. The supercavitation reduces required engine power/fuel consumption considerably
Once the tasks underwater have been done and the divers want to return to the vessel, they first connect the hoses back unto the vessel and set the compressor mode to 1B, causing the vessel to again fill up with air. A few 1-way valves open to dislodge the water, pushed outwards by the hightened pressure (valves located at the bottom since water is heavier than air). Once the vessel is half full (divers will need to hold their breath in the meantime), they can enter trough the hatch (by pressing MPB 1, located on the outside), and close the hatch. The vessel will slowly start to heighten. Once arriving at 1m below the sea surface, the flexible air hose will have fully been retracted and the rigid hose fully encloses the flexible hose. Since this hose is rigid, the divers can now boat with the vessel (with the flexible hose this isn't possible). The divers now set the compressor to mode 2, which directs the air to the outside (via CH1). This creates an air vacuum around the vessel (this is also known as a supercavitation bubble). The air vacuum reduces the required engine power considerably, and is a vital element to avoid needing a lot of fuel (which again adds weight, again increasing the cost of the vessel, ...)
Note: dimensions of the vessel not yet calculated; calculation should be just accurate to allow vessel to hover at 1m below the sea surface with air, and some 5-8m when filled with water.
