Abstract: A fibre-reinforced polymer composite shaft for transmitting loads along a central axis is provided. The composite shaft comprises a first interface surface extending along the central axis and comprising at least one helical groove and/or a plurality of circumferential grooves for engaging with at least one corresponding helical ridge and/or a plurality of corresponding circumferential ridges of a second interface surface of an end fitting. The at least one helical groove and/or the plurality of circumferential grooves comprises at least one flank with a flank angle of between 32° and 51°. In such an assembly, a preload structure is arranged to provide a radial biasing force to bias the first interference surface against the second interference surface.

Abstract: A retractable arch system for a boat is provided that includes at least four substantially vertical legs for permanent installation on the boat. A first traverse member forms a first arch and is removably coupled by first and second separable couplings to two of the legs. A second traverse member forms a second arch and is pivotally coupled by first and second pivotal couplings to the other two of the legs. The system has an upright position for extending of the first and second arches and securing the first and second separable couplings. The system further has a retracted position in which the first and second separable couplings are disassembled and the arches are pivoted downwardly.

Abstract: A universal support and mounting bracket for surveying instruments that provides a portable self-contained secure and stable mounting platform on structural support columns and other non-uniform surfaces. The mounting bracket device has multiple mounting areas to accept a variety of surveying and siting instruments.