I think I mentioned after the Vets that I needed a little more prebend to tighten up the jib luff. For whatever reason the mast was at about 8mm pre bend and I had trouble keeping the jib leach under control.
Looking at the MYA site, there are several device designs to put prebend into the mast. On the back of the pictures, I made the following. The outside roller bearing pulleys are set 12 inches apart and the pulley in the middle distorts the mast by tightening the bolt on the right side of the picture. Simple but effective. Under load it is easy to move the mast backward and forward to create an even bend. All the bits come off eBay and the wooden back is an old attic floor panel. Easy to build and adjust
It is quite scary how much bend you have to put into the mast to get it to bend permanently and I was nearly at the end of the bolt travel when I finally got the result I wanted. There is about 12 mm prebend which I will leave, until I see what my new BG sails (bought for the ranking events and the nationals) set like. I can always add more bend.
The jib luff and leach are much tighter now and I can rig the mast perfectly straight with more load on the jib luff. Now if anyone knows how to measure jib luff tension and can tell me what is the right amount of tension, I would be delighted to know.
Off to play golf for a few days. Next week, I will set up the BG sails and get ready for the first ranking event at the end of the month.