Thanks for reply. For IS 137 I have now 3 fins : S10 45/53 cm and S12 49 cm (just bought it), so that must cover it all. IS 137 you say is a great board and looking forward sailing soon. Your advice is not to replace FU 122 for a wider/bigger board, because of the massive range of IS 137. So I have to experience that, but some overlap is not wrong I think (because of conditions on my homewater with no steady winds). I must consider what to do
, too many (star-)boards so too many options ....