The outline quite often can be derived from a trapezoid form, a triangular form or an elliptic form. For wave and free-ride fins rather curved forms are delivering excellent results.
Figure 18: Outline and its basic geometric forms
Mostly the fin outline is a hybrid of the basic forms to cope with the specific demands.
Figure 19: Parameters of the outline
Sm mean geometric chord
Ss tip chord
Sw root chord
T/Sm aspect ratio
Ss/Sw taper ratio