In fins with a straight leading edge, the length of the leading edge is an important criterion for their upwind performance. But, with increasing length, resistance is also growing. Therefore, the maximum length of 70 cm for Formula fins is not ideal under all conditions. Tests with even longer fins have shown that the disadvantages outweigh the advantages.
Fins with a curved leading edge give advantages in control and manoeuvre; and for the average sailor also in speed. Disadvantages may be observed more often on close upwind tracks rather than at maximum speed.