Right now I have 5.0, 6.6 and 8.5 but since I had no luck using a harness I am mostly using 5m, otherwise I have a very hard time controlling the two larger rigs when the wind picks up. In general, I am having a tough time with my GO 171, spending more time in the water than on it.
After struggling with it for a couple of months, I bought a used Start 2002 in order to go back to the basics. In addition to the fins that came with both boards I have a 51cm weed fin which I am afraid might be too big considering the trainer rig I am still using. BTW, I have carpal tunnel problem in both hands which is frustrating me tremendously because it impacts by ability to hold on to a large rig. This will be taken care of over the winter. It sounds like I should not bother with smaller fins and focus on my rig handling skills in order to move up to bigger sails. I was advised that one of the secrets is to use the harness which is what I need to practice on the Start prior to returning to GO171L. So much to learn, so little time,