Abstract: In one exemplar embodiment, a knife for de-veining, peeling and butterflying shrimp is disclosed having a handle and an elongated arcuate knife blade secured to the handle and extending forwardly thereof, the knife blade having an intermediate toothed blade portion disposed adjacent the handle and an arcuate blade portion extending forwardly of the intermediate toothed blade portion, the arcuate blade portion having a curvature approximating the body curvature of a de-headed shrimp. The arcuate blade portion has an upper convex cutting edge disposed thereon and a lower concave cutting edge adjacent the tip of the blade. The intermediate toothed blade portion has a plurality of spaced teeth aligned in a ramp configuration from front to rear adjacent the handle. When used, the knife tip is thrust through the body of a de-headed shrimp to slice the shrimp body along its longitudinal length to a depth traversed by the upper and lower cutting edges.

Abstract: A mast is mounted onto a boat for 360.degree. rotation about its longitudinal axis, relative to the sailboat and the rigging for the mast. The rigging braces the mast against buckling and comprises a masthead, a transverse spreader bar and shrouds. A forwardly directed longitudinal channel in the mast receives bolt ropes at the forward edges of two soft fabric panels which together make up the mainsail. Each mainsail panel extends from its bolt rope within the channel out through a narrow slot in the mast. When sailing generally into the wind, each mainsail panel curves partially around its side of the mast and then extends rearwardly from a line of tangency with its side of the mast, generally contiguous the mainsail panel. Each side panel of the mainsail is secured along its lower edge to a separate boom, so that the two booms can be swung apart to move the two sail panels into a "wing-out" position, for use when sailing with the wind.

Abstract: A corrosion detector for determining the corrosivity of a fluid and the ability of a metal to withstand the corrosive tendencies includes a tubular test specimen and a reference specimen. The two specimens are of the same composition and configuration over the length of the test specimen over which measurements are made. Means are provided for maintaining the two specimens at a temperature within less than 1.degree. F. of each other. The corrosive fluid is passed through the test specimen. An alternating current is passed through the test specimen and reference specimen and the change in resistance of the test specimen relative to the reference specimen is measured in a phase sensitive Wheatstone bridge circuit to determine the extent of corrosion.