Outhaul calibration strips using the 5-9 method devised by the International Sailing Academy. To position the calibration strips correctly, rig your boat and make a mark on the top of the boom exactly 7 inches (178mm) from the end of the boom. Set your outhaul so that the tip of the sail is at the 7 inch mark. Decide what you are going to use as your reference point (I use the end of the outhaul primary line where it meets the block), and put your sticker on the boom with the ‘7’ aligned to your reference point. Each sticker is different – ensure that the 5 is at the front of the boom and 9 is at the rear of the boom on each side.