Abstract: A tilt detector is provided especially for use in operating sub-sea drilling equipment including a tool stack at the ocean floor. One such detector is carried by the stack to produce a first output; another detector is carried by a riser pipe near a ball joint interconnecting the stack and pipe to produce a second output, and the outputs are processed to facilitate maneuvering of a drilling vesssel. The detector includes:A. a container,B. liquid in the container having an upper surface tending to remain generally horizontal as the container tilts, andC. sensors having independently movable members engaging the liquid at spaced locations to sense the relative levels of the liquid surface at said locations and relative to the container during said tilting.

Abstract: This invention relates to an attitude meter which measures the orientation of a plane surface with respect to the magnetic North direction and a horizontal plane. The meter includes a hollow transparent sphere containing liquid for supporting a compass and a vertical indicator, combined with a rotatable arcuate scale for facilitating visual reading of the compass and relative position of the vertical indicator. More particularly, the arcuate scale includes vertical orientation indicia and is mounted for rotational displacement to a position immediately adjacent the vertical indicator. By this arrangement the vertical angle of the surface being measured may be read directly from the arcuate scale and the direction of inclination relative to the magnetic North may be determined from the point of intersection of the arcuate scale and the liquid supported compass.

Abstract: Angular displacements are measured relative to either an external magnetic field as in a compass or relative to a vertical reference as in inclinometers or the like by selective orientation of the device. A bistable weight balancing apparatus and a dual bearing support arrangement cooperate to provide two discrete balancing positions. Horizontal positioning of the device results in relatively even weight distribution around a needle bearing support which permits alignment with the polar line of an external magnetic field. Vertical orientation of the device permits an offset redistribution of the weight in the bistable balance to define a vertical reference. Digitally coded apparatus such as a disc permits circuitry to detect instantaneous orientation of the frame relative to a magnetic field or vertical reference. Circuitry logically cooperates with data read from specially coded tracks to insure accurate strobing of the output data free of ambiguities.

Abstract: A static non-swinging device for determining the course on board a vehicle comprising a magnetometer having three axes for determining the components of the earth's magnetic field along three axes connected to the vehicle, a vertical gyroscope and a computer for calculating the direction with respect to the vehicle of the horizontal component of the earth's magnetic field, wherein said magnetometer comprises on each axis a single coil having a saturable core controlled in such manner as to furnish a d-c voltage which is proportional to the component of the magnetic field along said axis.

Abstract: An apparatus for sensing the orientation of an inclinometer in both direction and magnitude for determining the velocity and direction of currents in a body of water having a magnetic north seeking sphere buoyantly supported in a housing. Implanted on the sphere is a plurality of tuned circuits of different resonant frequencies set at right angles to each other and a sense-drive winding or coil mounted about the housing. Upon applying a series of pulses of voltage to the sense-drive coil, the tuned circuits will oscillate with decaying amplitude at their resonant frequencies in the intervals between the pulses of voltage. The mean voltage across each of the tuned circuits is a measure of the amount and direction of tilt of the housing caused by the currents. The sense-drive coil senses these voltages across the tuned circuits and between the induced pulses of voltages, will transmit them to conventional recording equipment whereby a continuous determination of the currents velocity and direction are obtained.