That one is easy,

The spitfire crews are significantly better. They have ranked several times in teh top 20 at events like Texel. F16 crews have not yet reached the upper 100 I believe.

Besides, their is really not alot of difference between the two boats. Rig dimensions are very very similar, so too platform dimensions. Only the Spitfire is 25-30 kg heavier. These differences can never result in such great differences in overall speed so it must be the crew skill.

Wouter