Abstract: A cutting apparatus for cutting debris from a propeller includes a spool securable to the propeller or a propeller shaft so as to rotate with the propeller. The cutting apparatus further includes a cutter oriented to pare debris from the spool. In use, debris snagged by the propeller is wound onto the spool, whereupon the debris is cut away from the spool by the cutter.

Abstract: A centrifugal separator (10) for separating separable constituents of a fluid to be separated, includes a body (12) rotatable about an axis, the body having a cavity (22) therein. A divider (28) divides the cavity into a first sub-cavity (24) arranged for fluid to flow in a direction having a radial component and a second sub-cavity (26) arranged for fluid to flow in a direction having a component that is towards the axis of rotation. An inlet (58) leads into the first sub-cavity at or near the axis of rotation of the body. A first outlet (52) is in communication with a settling region (34) of the cavity between or connecting the first sub-cavity to the second sub-cavity. A second outlet (50) leads from the second sub-cavity at or near the axis of rotation of the body.

Abstract: A separator for separating particles entrained in a fluid is disclosed. The separator includes a sleeve adapted to be mounted over a rotatable shaft for forming a cavity therebetween, an inlet to the cavity, an outlet to the cavity and means for imparting a centrifugal force on fluid within the cavity. The means for imparting the centrifugal force is operatively connected to the shaft so that, in use, spinning of the shaft creates the centrifugal force. In use, a slurry of fluid and particles enters the cavity through the inlet, the particles are caused to separate from the fluid by action of the centrifugal force, and the separated particles and fluid leave the cavity via the outlet with the particles tending to be closer to the sleeve than the shaft.

Abstract: A drawing apparatus to assist in providing an artist with a true perspective of the scene viewed on a transparent surface viewed through a fixed eyepiece, the transparent surface being the concave side of a spherical segment encompassing about 60.degree. of arc which approximates the normal cone of vision.