Geometry: Cap Shroud/Chainplate

An article from AES.

Most sloop rigs which use rod rigging use a cap shroud angle of 10 degrees to the mast wall. This is normally considered a state of the art angle and it usually permits a reasonable compromise between sail sheeting and rig stiffness. Similarly, the chainplate angle for an overlaping 140% genoa on an inline spreader rig is normally about 13.5 degrees from the forestay (forward end of J). This defines the most common chainplate position. With the V1 shroud vertical and the cap shroud coming from the hounds at 10 degrees it then remains to obtain a modest spreader envelope to generate even spreader pokes on each spreader; kind of like joining the dots. For 110% genoa and swept spreaders on the gunwhale a whole different approach is required. However, it rarely pays off to have a cap shroud angle greater than 14 degrees. If the cap shroud angle that is too large this can actually lead to some torsional instablity which has been seen on carbon rigs. Carbon rigs have a fairly low shear modulus and are prone to excessive twisting, which can be annoying or unsettling in some cases.