I don't know if a tip is really appropriate. However, if you are really pleased with the instructor's performance, a small gift might be a nice touch, like a bottle of good booze, gift certificate to a local restaurant, etc.
Once you have decided on the appropriate bottle, first forward one to me, and I will be happy to evaluate it on its merits to help you decide if it is a suitable tip.
hunter Legend 37 Semper Paratus
Formerly - Tartan 34C Yawl