Hello all
If speed doesnt matter, would a larger fin on a race board always give more stability?
Or whether under chop/currents a large fin will be less stable?
Tnx

I would say a larger fin on a race board will offer you more stability regardless of chop and currents.

I would recommend using a very narrow fin, one with a small chord.

The reason is that you will have less hold than a wide fin at rest, so less stability, but as soon as you paddle you will get nearly as much hold and stability than the wider fin.

This way you will have the best of both worlds:
- stability and directional stability while paddling
- but ability to do quick turns by stalling the board, for instance around buoys

Things like this:
www.oceanspecific.com/products/os-r-f3-blaze-sup-race-fin
www.makanifins.com/products/kawa-stand-up-paddle-sup-race-weed-fins

But wider fins have their use, for instance in sprints to be able to apply max power without bothering managing the row effect, e.g:
www.supgower.com/2016/11/sup-racing-fins/
But you will turn like a barge.

Having the right size fin is important ,on my 14 I like it with a 10 inch fin in flat and currents and if swell riding I prefer
a 9 or 9 1/2 ,but yes the 10 inch is a lot stabler and provides better pointing ,if thats what your after ,make sure you have fibreglass or carbon fins NOT plastic flexible fins they are very unstable ,and provide little performance ,

Thanks guys!