If you're getting that much backwind in that little air, it sounds like the main needs flattening. Is your backstay good and tight? Vang on at all? Outhaul and cunningham? Sheet socked 'way in? You have probably already done all these things. Next step might be to try opening up the slot by barberhauling the jib OUTBOARD, perhaps with a snatch block on the rail. This will affect your pointing ability (though perhaps not really that much) but could increase speed markedly. Otherwise, it could be that your main is simply too blown out and baggy, and you need to give Omar the tentmaker a call about a getting yourself a new (flatter) main.
Yup, I put tension in the main halyard, backstay, clue outhaul. I have not rigged a cunningham yet but its on the list. I need to add a deck plate under the mast first. I have not tried the to open the slot yet, thanks for that tip.
According to the sail maker, the sails are 7 years old and are pentex laminates. He said that material is similar to Dacron and polyester, stronger than Mylar but weaker then Kevlar. They have not seen much use in the past few years, but I don't know before that. The surveyor remarked that they seemed to be in excellent shape but he didn't see them under sail.
I called the sail maker again and he advised that I'll know when they are ready to give up the ghost based on where the draft is. He said if my 150% has a draft 50% back, then its done. He said the main was okay with a draft 50% back but not further. I'll hopefully get a chance to check them tomorrow, if it does not rain.
To answer a few other questions, I don't have a furler, but rather a dual track foil. I predominantly have been racing, very little cruising. I'm still looking for a crew that wants to race as much as I do, hopefully I'll recruit a great crew by next season. The raid has really put a damper on stuff this season.
I have been experiencing weather helm, and I am trying to retue the rig to reduce it. My mast is like a phone pole so I don't see it bending much.
I would also hate to buy a sail I don't need, but if I need new ones I'll get them. I just want to be sure first.