An illustrated guide to successful mainsail trimming for power and acceleration on a yacht or a dinghy. Mainsail trimming is one of the most physically and mentally demanding roles on a boat. It?s also one of the most important requiring understanding of sail shapes and the controls used to achieve them. This book explains everything you need to know about fine mainsail control without blinding you with science. Sailing terminology has been reduced to the bare minimum and the book is concerned only with making your boat go as fast as possible.