The present invention provides an angle changeable apparatus and an oar such that the shaft angle is easily adjustable. Disclosed is an angle changeable apparatus 1 for variably changing an angle of a shaft 110 inserted in a sleeve 10, including: a shaft-side member 20 fixed to the shaft 110; a sleeve-side member 30 fixed to the sleeve 10; and a slider 40 configured to slide between the shaft-side member 20 and the sleeve-side member 30, wherein the shaft-side member 20 has a first guiding part extending in a shaft direction, the sleeve-side member 30 has an elongated hole 31 extending in an oblique direction relative to the shaft direction, the slider 40 has a groove 41c guided by the first guiding part and a slider main body 41 guided by the elongated hole 31, and when the slider 40 slides, the shaft-side member 20 and the sleeve-side member 30 are subject to relative rotation so that the angle of the shaft 110 relative to the sleeve 10 is changeable.

An accessory sleeve that fits over an oar combination is disclosed herein. The sleeve is configured with a ruler or a tape measure printed on a surface thereof. Further, the sleeve comprises neoprene that yields proper feel and grip while stretching slightly so that the sleeve can be easily applied and removed, if necessary. The ruler is supported underneath by a nylon strip that prevents shrinking initially and any stretching during the useful life of the sleeve.

Provided herein are flotation devices for use with a stand-up paddle and a stand-up flotation paddle. The flotation device has two hemispheres and a pair of stop collars. The hemispheres are secured to each other around the shaft of the stand-up paddle and secured to the shaft via the stop collars. The stand-up flotation paddle has the flotation device secured thereto.

An oarlock that is designed to be used with an oar-right. It is an oarlock that has a pin for securing the oarlock in an oar holder or gunwale of a boat. A U-shaped bracket is attached to the pin. There is a formed piece that has a cylindrical upper portion and a lower squared portion that is secured to the U-shaped bracket. An oar fits into the cylindrical upper portion and the oar-right fits into the lower squared portion of the formed member. The U-shaped bracket can rotate on the pin, which means that the oarlock can rotate 360 degrees and the formed member is free to pivot between the arms of the U-shaped bracket. Because the formed piece is a closed member, the oar cannot come out of the oarlock no matter how much the oar maybe moved or jostled by rough water, nor can the oar rotate on its own axis.

Provided herein are flotation devices for use with a stand-up paddle and a stand-up flotation paddle. The flotation device has two hemispheres and a pair of stop collars. The hemispheres are secured to each other around the shaft of the stand-up paddle and secured to the shaft via the stop collars. The stand-up flotation paddle has the flotation device secured thereto.

An accessory sleeve that fits over an oar combination is disclosed herein. The sleeve is configured with a ruler or a tape measure printed on a surface thereof. Further, the sleeve comprises neoprene that yields proper feel and grip while stretching slightly so that the sleeve can be easily applied and removed, if necessary. The ruler is supported underneath by a nylon strip that prevents shrinking initially and any stretching during the useful life of the sleeve.

A method of three-dimensional fabrication of an object is disclosed. The method comprises: forming a plurality of layers in a configured pattern corresponding to the shape of the three-dimensional object, at least one layer of the plurality of layers being formed at a predetermined and different thickness selected so as to compensate for post-formation shrinkage of the layer along a vertical direction. In various exemplary embodiments of the invention spread of building material of one or more layers is diluted at least locally such as to maintain a predetermined thickness and a predetermined planar resolution for the layer.

A method of three-dimensional fabrication of an object is disclosed. The method comprises: forming a plurality of layers in a configured pattern corresponding to the shape of the three-dimensional object, at least one layer of the plurality of layers being formed at a predetermined and different thickness selected so as to compensate for post-formation shrinkage of the layer along a vertical direction. In various exemplary embodiments of the invention spread of building material of one or more layers is diluted at least locally such as to maintain a predetermined thickness and a predetermined planar resolution for the layer.

A sleeve and collar system for an oar includes a sleeve configured to couple to a shaft portion of the oar. The sleeve includes an outer surface. The system also includes a wear collar configured to couple around the sleeve at each of a plurality of longitudinal positions along the sleeve. The wear collar is configured to bear substantially all direct contact from an oarlock during a rowing stroke of the oar. A radially inner surface of the wear collar is shaped to be complementary to at least a portion of the sleeve outer surface, such that the wear collar inner surface and the sleeve outer surface cooperate to maintain the wear collar in a predetermined orientation about a longitudinal axis of the sleeve at each of the plurality of longitudinal positions.