4.1.1.4 Leading edge

The form of the nose is influencing the fin performance to quite an extent. A big nose radius (a blunt nose) allows a bigger angle of attack and produces more lift. The speed potential is reduced.

A small nose radius is causing opposite effects. There is an increased demand on the technical standard of the sailor to get good all-round properties. If the standard of the sailor is a high one, a small radius and a flat profile may become an advantage.

 

Figure 14: The leading edge


NR   nose radius

S      chord

A small nose radius is good for speed oriented laminar profiles, bigger radii are occasioning more lift and are not that sensitive in their reactions.

Damages on the nose are reducing the lift potential of the fin. Regatta sailors should remember that.

 

There is a correlation between nose radius, maximum thickness, thickness distribution and the width of the fin which was confirmed by practical tests but still is a topic in discussion. One thing can be said for sure: there has to be a certain radius of the leading edge, otherwise in sideways drift a constant flow around the fin cannot be developed. In addition a sharp leading edge would be dangerous.