Abstract: A fully inorganic boron nitride paste, containing 80 to 94% of a boron nitride paint and 6 to 20% of ceramic fibers, is provided to allow the process of manufacturing boron nitride “shell” coatings of 0.0313 to 0.25 inch onto ceramic substrates chosen from a wide range of densities. De-clumping of the ceramic fibers such that fiber lengths are greater than 100 micrometers and clumps are less than {fraction (3/32)} inch improves boron nitride “shell” layer uniformity. Boron nitride content of greater than 36 wt. % (or about 50 vol. %) in the boron nitride “shell” provides ceramic structures with a matrix of boron nitride that provides long-term nonwetting behavior for molten nonferrous metals.

Abstract: A rudderless sailboat having a hydrodynamic symmetry fore and aft which can be sailed equally well in either direction. The craft is steered by tilting the mast and keel. In an alternative embodiment the sailboat also has no keel. The hulls are rigid and have a v-shaped bottom. While sailing forward, the sail can be rotated past the angle of zero angle-of-attack to that angle-of-attack where the wind is aback on the sail. This stops the boat and causes it to sail back in the general direction from which it came. This sailboat maneuver is called a tack aback.

Abstract: A rudderless sailboat having a mast keel assembly which can be pivoted fore or aft to generate a moment of force to effect easy precise sailboat steering. In one embodiment including a catamaran, the keel is integral to the mast and thus pivots correspondingly but in an opposite direction from vertical as the mast is pivoted fore or aft. In yet another embodiment, a monohull is provided wherein a frame extends laterally over each side rail of the hull and downwardly to a respective keel, wherein the mast extends upwardly therefrom. The frame is secured in an oar lock on each side rail. Thus, as the sail and mast is pivoted forwardly, each keel disposed lateral of the side rails is pivoted rearwardly. In still yet another embodiment, a slope-rigged sailboat is disclosed wherein the mast can be pivoted fore or aft by adjusting the length of the forestay and backstay. The keel is stationary, and a winch is used to adjust and secure the position of the mast.