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S.T.A.S.I.S. Buoyancy Control System

...or S.T.A.S.I.S. BCS for short is an electronic ballast system for achieving neutral trim and buoyancy of an underwater vehicle using 2, 4 or 6 trim tanks. The system utilises state-of-the-art logic to achieve optimal buoyancy conditions for small and large vessels alike.

- 2 tank mode - the system utilises a bow tank (1) and stern tank (2) to account for all necessary changes in buoyancy, filling and draining the tanks as required and cross-feeding ballast between them to keep longitudinal stability in check. This mode is recommended for smaller vessels as it takes least amount of space but will become cumbersome for large vessels.

- 4 tank mode - the system utilises a bow tank (1), stern tank (2), port tank (3) and starboard tank (4) to account for all necessary changes in buoyancy. The tanks 1 and 2 become dedicated tanks for longitudinal stability initially being filled halfway to allow for the greatest leverage for trimming the vessel. Tanks 3 and 4 are used for buoyancy corrections. The system makes sure that tanks 3 and 4 are keeping similar amounts of ballast water to prevent unscheduled rolling of the vessel. This mode is recommended for medium to large vessels.

- 6 tank mode - the system utilises a bow tank (1), stern tank (2), forward port tank (3), forward starboard tank (4), aft port tank (5) and aft starboard tank (6) to account for all necessary changes in buoyancy. The tanks 1 and 2 become dedicated tanks for longitudinal stability initially being filled halfway to allow for the greatest leverage for trimming the vessel. Tanks 3 through 6 are used for buoyancy corrections. The system makes sure that tanks 3 through 6 are keeping similar amounts of ballast water to prevent unscheduled rolling and pitching of the vessel. This mode is recommended for medium to large vessels.

- It is highly advised to ONLY use the system when the vessel is not in motion as it will assume that the vessel is stationary and all torques and forces acting on the vessel are caused by ballast. Keeping the system on when travelling might cause the system to create an out-of-trim condition which will become apparent as soon as the vessel comes to rest. Therefore the system (and especially the buoyancy control program) should be disabled prior to moving the vessel.

- Depending on the design of drain system of the trim tanks, draining of ballast water might become increasingly more difficult and eventually fail as depth increases. Therefore usage of buoyancy control program at high depths should be carefully considered in accordance to the vehicle design as it might cause an irrecoverable negative trim condition. Use of longitudinal trim control program is safe in this regard in all tank configuration modes as all the water involved in this program is already on board the vessel and none is ingested nor expelled.

- All logic nodes descriptions relate to the relevant modes of the system. If you have opted for a mode that does not require all tanks (i.e. MODE 2) all nodes that do not have MODE 2 in their description can be removed and the microcontroller resized to take a more compact form.