I am wondering whether it is worthwhile replacing the cnetre fin on my missus Starboard Widepoint 10.5 with a longer fin. The board currently has a thruster setup, 4.7 inch side fins and 170mm centre fin. This compared to my Nalu with 10.5 inch centre fin.

She is complaining that the board doesn't track that well in the flat water and I have read that fin length can help with that. I just don't want to spend big bucks to get a matching fin (she is pedantic) for not much advantage.

And if I was to get a larger fin - would I necessarily remove the side fins, or keep them there?