See another thread somewhere in here re the bloody mary this year.
The RYA are recommending 930, problem with a Cherub is when the conditions are right (no beat against the tide up the shore, no tight reaching where others can kite and some other factors, generally no sign of land or dirty wind from others !) then 930 is generous, we've won by some distance on that, but also narrowly by a few seconds. On a different day where conditions are wrong (reverse of above) then we're very midfleet on 930.
830 seems low to me in your first season at a club with no real record of current boats, on the right day you might be doing OK on it, on other days I'm afraid Alex wont be going home with chocolates. Whether you can do anything about it ......