Caspar vs SL7

I received my first pair of Caspar fins yesterday, a 25 and 27. The finish is very impressive in 09, the body has a light sanding in the direction of flow and the leading and trailing edges are finished nicely.

Comparing the 27cm Caspar with the 27cm SL7 the Caspar has a shorter chord length at the base and a little more rake. The Caspar foil shape also has more volume nearer to the trailing edge and almost a lump as it narrows into the last quarter of the foil profile. It is much more subtle than in the other dedicated assymetrical speed fins that I have seen.

The outlines below are the SL7 in orange and the Caspar in grey.

I took some quick measurements of the two foils.

SL7

• Base chord length - 91.5mm
• Base chord width - 8.3mm
• Base chord AR - .091
• Wide Point - 35%

Caspar

• Base chord length - 85.3mm
• Base chord width - 8.3mm
• Base chord AR - .097
• Wide Point - 42.5%
  

The Caspar wide point moves back slightly down the length of the fin to 48% and the chord AR(Aspect Ratio) drops to .089. The SL7 maintains the chord AR and wide point measurement down the length of the fin.

I am looking forward to testing these babies on my CA44. I anticipate the 27 will work well with the 6.7 RSR and the 25 with the 6.2 Slalom MkIII I have on the way, and possibly my 5m RSR on tighter courses. I also hope to get sizes either side of these 2 once I have had a chance to fully test them.

Boards I have made.

Here are some of the boards I have made over the years. I will give more detailed info on the build steps of the more recent boards soon...

Board 1 - "The Dominator" (1993)




Board 2 - "Exile" (1994)




Board 3 - "HMR 290" (1995)




Board 4 - "HMR Speed" (1996)




Board 5 - "Flow 66" (1998)




Board 6 - "Hyper 111" (2004)




Board 7 - "S66" (2005)

Ape Index

I remember reading an article years ago on Ape Index - calculated by dividing armspan by height. It is usually around 1 but a positive ape index is considered benoficial for sports such as rock climbing, swimming and windsurfing (speed and slalom). Most people know height (and weight) can be an advantage(for holding down more sail area) but it is less of an advantage if you cannot get outboard to take full advantage of your assets. You can use long lines but unless you can get your shoulders outboard you are not maximising your righting moment. My arm span is 198cm and my height is 193cm so my ape index is 198/193 or 1.026. I have heard it desribed as +5 (span 5cm more than height). Measure you arm span and work out yours, it may be of interest when you are tuning equipment and technique.

Welcome to my Blog

Inspired by some great blog pages I have decided to take the jump myself. I hope to do some articles on DIY windsurfing equipment such as boards and fins as well as info on speedsailing in South Australia.