Actually, opening up the rig doesn't mean throwing everything loose. It refers to the how the sail looks. It should not have too much draft or a hooking leech. In fact a leech that falls off by bit is often best. (But not always).

Each sail is different in what to do with the controls to achieve this. On my boat (but I have a mainsail with a building error) I need to pull the downhaul on to high medium, rotate relatively far out and use little sheet tension. Outhaul is such that just a fist is between the boom and sail at midpoint. This seems to work best for me when singlehanding in light winds. In strong winds I crank on the downhaul very hard, have the rotation arm points to the back of the daggerboard (= to much for properly cut sails) and reasonable mainsheet tension.

My mainsail will flatten out towards to top and have a noticeable (but not alot) of twist. Medium winds condition I sail with a more tight rig; here I need to pull very hard on both downhaul and mainsheet as per advice of Daniel van Kerckhof (Taipan champ). AND I MEAN HARD !

These settings may not work for you and are probably specific to my mainsail design (with the known error). In my case I have too much draft in the top of my mainsail. This was just to show that opening up the rig is different from releasing all the controls. It just refers to not hooking the leech or sail with to little twist. Nor increase draft to much if looking for power; it if often better to flatten the rig open up the head and let the sail stream. Also a lesson by Daniel "Flat is fast". You'll feel less powered up but may well go faster never the less. Never, and I mean NEVER, adjust the rig setting to your position on the boat (liking keeping you or your crew on the wire) set the rig for max speed and adjust your position to maintain that setting. Not following this simple rule (a common mistake) can make a huge difference to performance; especially so to the F16's.

And ohhh ask JC for advice and trim tips. He seems very willing to give us some pointers after having sailed the F16's at the Alter cup 2007.

I hope this helps

Wouter