The wind has blown all day and I was on the water just after 13:00 on my 89l Falcon and beloved Ka Koncept 6.6. I held this all afternoon - overpowered but in control. Gareth came out on his 5.3 on a 90l Blast and had a tremendous sail. The fact that our sails are so far apart in size got us talking about whether it is better to be overpowered or comfortable. I believe that the answer depends on what you are trying to achieve. I always use this type of sailing as an opportunity to practice sailing fast over rough water and concentrate on keeping the hammer down for longer and longer stretches. My aim is to improve to a point where I can be comfortable going at full tilt for each entire leg. I'm not there yet and catch myself slacking off as soon as I am ahead and after each bad tailwalk. Not good. The answer as I see it, is that if you want to get the most enjoyment from your session, rig down to a size where you feel you can keep the hammer down for the entire leg. This will provide max fun and some excitement. My training sessions (like today) comprise max excitement with quite a bit of terror thrown in.
The secret to sailing overpowered is to balance the power of the sail positioning the force right onto the fin. This you do mainly with downhaul and outhaul. Too much outhaul can bring the centre of effort forward making the board feel heavy and can result in spinouts (because the force is focussed in front of the fin - no bite) Too little outhaul and the centre of effort moves back resulting in the force bearing behind the fin causing the board to tailwalk. Anyway quite a big topic which also involves the sail (some sails push down while others lift up), footstrap and mast foot placement.