There are two distinct styles of wakesurf boards.
Skim boards are short, thin, and wide and are ridden with one fin or no fins. Although some Skim Boards may have more than one fin, for the purpose of competition a maximum only one fin is permitted. (*Junior categories are exempt from any fin rules)
Surfboards are longer and thicker. They have a minimum of 2 fins and as many as 5.
For the purpose of competition, Surf Boards must have a minimum of 2 fins with a 2 inch minimum height for the fins.