In the old days fins were made from Lexan and polyamide with glass fibre additives. Their endurance was rather limited and they did break quite often.
As windsurfing was developing, stiffer materials were used. Glass fibres were combined with various resins like vinyl ester, polyester and epoxy. These materials were softer than G 10, but some like polyester fins were excellent wave fins.
G 10, G 11 and other compressed materials made from glass or carbon fibre combined with epoxy resin, contain a high portion of fibre, hence they have a much better fatigue resistance.
This development led to a quantitative improvement with a high fibre concentration, but the right twist and flex had to be found via thickness and outline.
If one wants to consider the qualitative aspect a bit more, the main lines of force have to be found. By following these lines with unidirectional fibres, the fin torsion can be influenced without changing the profile. This aspect is taken into account by the moulded fin.
Today there are basically two types of construction that are of relevance:
- the fin can be milled from a panel of G 10 or another enforced material
- the fin is a moulded fin, produced with the help of a female mould.