Not Very Smooth Racing Bottom
Bottom preparation really comes into play in two separate conditions, very light air and in gusty winds. In light air the difference is very noticable and comes into play when it makes the difference in how much speed you can build by way of apparent wind. What happens in light air is that as a boat builds up speed its also builds up apparent wind and with this building of apparent wind comes more speed and with more speed comes more apparent wind until the drag on the boat becomes large enough to stop the boat from increasing in speed. In these extreme light winds a boat with a smoother bottom will get up to speed quicker and hit a higher speed. This higher acceleration can means minutes coming out of a tack and will also allow the faster boat to place itself more strategically on the racecourse.
In gusty conditions, a boat dispurses the energy of a gust in two ways, accelerating and heeling. Acceration is good because it is faster, and with more speed there is less leeway and less rudder angle required. When you heel the opposite occurs, Leeway increases and rudder angle needs to be increased which can often actually reduce speed. Here again the increased drag of a rough bottom means more heeling and less accelleration. Not good!
I don''t do a full blown racing finish on my boat but I do have it sprayed and sanded after application. On my smaller boats I would use a hard bottom and burnish afterward, if nothing else but for the pyschological need to eliminate a rough bottom as an excuse for a poor finish. 8^)