I make 2 different quad shortboards. First is a roundtail with your average nose and center thruster numbers with a 14 1/2" tail.
Very fast and free off the top. These boards are more free to go wherever you want on the wave. I make the roundtails with either single
concaves running from the front foot back, or a full double concave running through your feet for maximum drive off the bottom depending on the riders preference and the conditions it's made for.
The second is a swallow tail. A little narrower nose, deeper single concave. One round curve through the tail helps control the speed and keep it loose and snappy.
Both are meant to be ridden about the same size as your everyday thruster if any an inch smaller. The numbers are pretty adjustable and customizable for everything from small wave round tails to step-up pintails."