With the gunnels on wing-rigged boats being considerable lower than the pins, measuring span can sometimes be a headache. For sculling boats, this is compounded by the need to make sure each pin is the same distance from center line. Traditionally after setting the span, measuring the diagonal from the gunnel to the opposite pin has been necessary to ensure equal distances for each pin.

Enter WingSpan. Once you've measure the width of the boat and the vertical difference between gunnel and pin once, you can quickly and easily calculate the diagonal value for the span you want. From there, you can adjust each pin by simply measuring the diagonal value, thus eliminating the guess and check.