Just measured the S27 carbon 100 approximately between 15-16mm. S27 AL was maybe slightly narrower at 15mm. Chord much wider on AL and it does sail slower than the carbon. Measured a new North 100 Carbon while I was at it.also 15 mm at the bottom but increases to 17 mm at the top.
in contrast a windsurf fin is usually around 7-9 mm. Hmmmmm
