The “Center Main” thread Colin refers to, is all about a full center main. The disadvantage of this is that you can’t point as high as with a boom end sheeting arrangement. (And also it’s illegal for racing). The photo’s you will find if you follow the links given in that thread, clearly show how hard it is to sheet the boom in to a position above the transom corner. With boom end sheeting and a bridle we can sheet the boom in to a position almost above the center line of the boat.
Most center main set ups keep the purchase at the boom end. Only the sheet end is led along the boom to a location above the thwart and from there down to a swiveled ratchet block and swiveling cleat. This arrangement is race legal since the main purchase is still at the boom end. Also all trim options are the same. This arrangement is just as good as a boom end sheeting as far as trim and pointing goes. It is only a matter of personal preference. And also, there is no need to double the purchase since the actual purchase stays ate the boom end. This means that the boom is less stressed. (See “Center Main” thread for explanation).
A search on this forum should reveal some photo’s and more accurate descriptions of the latter set-up. Also there are several essays on the subject to be found on the WIT web-site: http://www.wayfarer-international.org/WIT/WITindex1.html
The search function of this forum is found at the top of this page, just below where it says: “UKWA Forum” and “Wayfarer Association”.