Olympic triangle to re-align the course to the new wind direction. With a 60, 60, 60 triangle, if the wind shifts 15 degrees either way, one of the reaching legs will be a 45-degree broad reach, while the other will be at 75 degrees to the wind and will be a close reach. Many dinghy classes have a target length for a race for the first boat. This time might take into consideration the age of competitors, how physically demanding the class is and how physically demanding the conditions are. 100 minutes is often used by Herons in Australia as an informal
Sonobe as the other three faces. It will have a right-angle apex (equivalent to the corner of a cube) and three tab/pocket flaps protruding from the base. This particularly suits polyhedra that have equilateral triangular faces: Sonobe modules can replace each notional edge of the original deltahedron by the central diagonal fold of one unit and each equilateral triangle with a right-angle pyramid consisting of one half each of three units, without dangling flaps. The pyramids can be made to point inwards; assembly is more difficult but some cases of encroaching can be obviously prevented. The simplest shape made of these