Took some years but finally decided to mount European standard spi because of 2 reasons:
- fellow H16 sailor joined me so we modified 2 cats simultaneously so we can continue catsailing together - with equal gear !
- sailing alone mostly the 17 m2 might be easier to handle than suggested alternative (f18 spi = 21 m2)

Results: 4-5 Bft and 2 man crew just fun. Did enjoy H16 sailing but this is adding another dimension. However alone and unsteady (but light !) wind will require some more training.
Hope to be able to upload pictures sometime