I put your advice into practice at the weekend and it was very helpful. I felt much more in control of the sail, though to release the power in the sail in gusts, at the same time as pushing my back hand out slightly to sheet out, I also had to pull the mast back and towards me slightly (as in a quick jerk) at the same time to spill the wind. Should I do this? It felt that if I didn't the sheeting out action created a pull from the sail that was overwhelming and I would be catapulted. I think that this is because when I have to sheet out quickly in a gust (i'm on a lake) as my back hand pushes my body weight comes slightly more towards the board and also the mast may move forward slightly. Its hard to analyse it at the time but it does create a feeling that if I sheet out I receive an even greater pull than If I pull against the sail and lean back (though if go too far back I stall).
On a slighlty different track, I've noticed that its difficult for me to go downwind whilst in the harness. As I'm attached to the sail and have to move forward to move the sail towards the nose and head downwind, I am off balance and do not have enough leverage to withstand the pull on the sail (then get wet). If I lean back then the sail comes back and I move back onto a beam reach. If I let some of the power out of the sail by sheeting out as I tip it forward then I lose the power I'm trying to get to plane. I dont have these problems when not in the harness as I can hang my weight off the boom much further back than when I'm hooked in.
Just a few things that came up during harness practice.
Thanks for the advice Roger I think I'm starting to get there,