Robbin: The M-15 was not supplied with a boom vang but several owners have installed their own. send me your e-mail address and i'll forward you some pictures of mine. The block on the side of the boom and the jam cleat are for the "jiffy" reefing of the main sail (again added by the owner). I have double reefs so theres a flat block and jam cleat on either side of my M-15 boom for that purpose. The outhaul was also re-rigged by the previous owner. It comes from the factory as a one to one ratio and most folks use a three-to-one. There are some excellent photos of the reef arrangement and the outhaul on doug kelch's web site. Go the the main page and look up owners. Hope this helps. good luck Don Ludlow - M-15 # 620 Sweet Dream