 In 1953, drawing on his professional background in aerodynamics, Czeslaw Marchaj designed modifications (within class rules) to his Finn class racing boat and subsequently sailed it to a surprising win in a multiday Warsaw-Gdańsk river regatta.Asked by the Warsaw sailing clubs community about his race performance, he prepared and presented a series of lectures on sail aerodynamics during 1953/54 winter off-season.These lectures had been edited into the first version of the book ""Sailing Theory and Practice"".