Simon, some are rigged with 2:1, some 3:1. On my old boat (GBR527) it's a cascaded 4:1!

2:1 at the tack and the line from this comes back along the 'sprit, terminates in a Harken mini ball bearing block which is part of a 2:1 arrangement with a clamcleat. This makes adjustment really easy for the crew in all conditions.