Hi John,
You obviously know that you need fuller sails, to give more power, which you are trying to achieve by easing sheets, and the foot of the mainsail. But there are a few other things which you can do as well.
Do you have a backstay tensioner? If so, then you need to have very little tension on it in order to induce some forestay sag, which will give fullness to you foresail. Also have you tried easing the tension on your halyards, as this is also needed to give fullness (power) to the sails.
On the mainsail, you need to keep the boom fairly close to the centreline of the boat, but without hauling in too hard on the mainsheet so that you keep the leach fairly open. You can do this by bringing the traveller up the track, moving it to windward, and keeping light tension on the mainsheet to keep the boom where it's needed.
You may find that you need to sail off the wind a little, to keep the boat sailing, and you can point up a bit when there's a flatter section of water, also watch the waves, and try and steer round the worst of the peaks.
But of course all this will not help if you have excessive weather helm, so in trimming your sails, sheet them so that they are well balanced to produce neutral pressure on the tiller.
You may have tried all this, but if not give it a go, and I'm sure you'll notice a difference.
Hope this helps.
Tim
