Question; when is a straight mast not a straight mast?
Answer.....when you let the backstay off!
A picture is as good as a thousand words, this will give you some idea of how much
prebend to put in your mast for starters, if you have never done it before! Please note
this is a 12mm mast on my boat, 11mm masts bend quite a lot more under load and do
usually require more prebend than this! If you're not going to use prebend you had
better have a really stiff mast or else your forestay will look like a banana in a breeze,
and even my headsails will look more like spinnakers than working sails! Tip.. a little
forestay sag in light weather is not such a bad thing, ease off your sidestays a touch as
well in the lighter stuff to acheive this.